JP2007250736A - Semiconductor laser device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the end face damage of a nitride semiconductor material due to dry etching and the propagation of a dislocation or defect to a light emitting region to solve the problem that it is difficult to exclude adverse influence on the light emitting characteristic and reliability. <P>SOLUTION: The semiconductor laser comprises a first conductive clad layer 2 on a region R11 of a substrate 1, a first conductive electrode 8 on the region R12 of the substrate 1 adjacent to the region R11, an active layer 3 on the region R21 of the clad layer 2, and a second conductive clad layer 5 forming a current stricture part on the active layer 3. A region R22 of the clad layer 2 located between the regions R21, R12 in plan view is a dislocation propagating block region where its topside height is lower than the underside of the active layer 3 and higher than the height of the topside of the region R12 of the substrate 1, and the block region is distant from the current stricture part in plan view. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  III-V nitride-based semiconductor materials based on GaN have light emission characteristics that cover the visible region from ultraviolet to red, so light sources for next-generation high-density optical disks, white light sources, etc. Semiconductor light-emitting devices such as light-emitting diodes and laser diodes that use this in the active layer have been actively developed in recent years, and the market is expected to expand further. .

  FIG. 11 shows a cross-sectional structure of a general ridge stripe type nitride semiconductor laser device having positive and negative electrodes on the same surface side of the substrate. In this apparatus, an n-type AlGaN cladding layer 102, an active layer 103, an optical waveguide layer 104, a p-type AlGaN cladding layer 105, and a p-type GaN contact layer 106 are sequentially stacked on an n-type GaN substrate 101. The p-type AlGaN cladding layer 105 is processed into a ridge stripe shape, and a p-type electrode 107 is formed on the ridge stripe (portion indicated by arrow A4 in the figure). Further, a part of the portion where the ridge stripe is not formed is etched to a depth reaching the n-type GaN substrate, and the n-type electrode 108 is formed on the bottom surface of the etching.

  Thus, in the nitride semiconductor laser device in which both positive and negative electrodes are formed on the substrate surface, a non-conductive substrate can be used as compared with the semiconductor laser device in which the n-type electrode is formed on the back surface of the substrate. In addition, although there is an advantage that flip chip mounting is possible, there is a problem in process.

  In the portion where the n-type electrode is to be formed, it is necessary to etch away each layer over a depth of several μm up to the n-type AlGaN cladding layer. Nitride-based semiconductor materials have high chemical stability, so that wet etching is difficult, and dry etching using chlorine gas or the like is necessary. Moreover, in order to ensure an etching rate, a certain high acceleration voltage is required. For this reason, there is a problem that an etching damage layer is formed on the end face of the active layer on the etching side wall by high acceleration voltage and long-time dry etching, which may affect the light emission characteristics and reliability.

  Furthermore, there are specific problems with nitride-based materials. Nitride-based semiconductors are more elastic and harder than conventional compound semiconductors such as GaAs and InP, and therefore tend to form dislocations and relax when affected by lattice strain or strong stress. It is thought that there is. Therefore, if etching damage or roughening occurs on the etching end face, or if a process that applies high temperature or stress to the crystal, such as subsequent heat treatment steps or mounting, is considered, there is a possibility that dislocations may occur starting from this. It is done. That is, the nitride material has a problem that not only a damaged layer is formed by dry etching as described above, but also dislocations and defects are likely to occur based on etching damage and side surface roughness. It is known that dislocations existing in the crystal easily propagate by current injection or storage / process at a high temperature. Therefore, dislocations and defects generated on the etching end face may also propagate to the light emitting region in the stripe.

  Dislocations generated by damage or the like on the etching end face propagate through the crystal by a high temperature process or current conduction. In the case of GaN or AlGaN which is a nitride-based material and does not contain In, dislocations are basically easily propagated in a direction perpendicular to the substrate, but the presence of an InGaN layer is characterized in that the propagation direction is easily bent horizontally. The InGaN layer is relatively less elastic than GaN and AlGaN and has a compressive strain on the substrate, so it is considered that the force to generate dislocations and relieve stress is particularly likely to enter this layer. It has been. Since the active layer of a general nitride-based semiconductor is made of InGaN, even if the distance between the etching end face and the light emitting region is secured and the damaged layer is sufficiently separated from the light emitting region, the InGaN active layer is active. The dislocation that has entered the layer further propagates horizontally, so that it easily reaches the light emitting region in the InGaN active layer, and it is impossible to completely eliminate the influence of damage on the end face.

  Therefore, not only the damage directly generated on the end face of the active layer, but also the propagation of dislocations from the damaged area of the entire etching end face including the layers below the active layer to the active layer, and further the light emitting area As a result, the light emission characteristics and device reliability deteriorate.

  Such etching damage is also a problem in conventional InP-based and GaAs-based semiconductor light-emitting elements, and one solution is a method disclosed in Patent Document 1, for example. Patent Document 1 relates to a method for manufacturing a buried semiconductor laser of 1.55 μm band using an InP-based material. After forming a mesa by dry etching in a buried mesa manufacturing process, hydrobromic acid, bromine and water are used. A method for removing a damaged layer caused by dry etching by performing wet etching using a mixed solution is disclosed. The liquid mixture of hydrobromic acid, bromine, and water has a very small difference in etching rate depending on the composition and the like within the range of the semiconductor material used for the InP-based light-emitting element, so that the damaged layer can be removed. It is possible to obtain a smooth end face. As described above, in a conventional InP-based or GaAs-based semiconductor light emitting device, when a dry etching process is necessary, a method of removing a damaged layer by performing wet etching after dry etching is generally used. Yes.

In addition, as a prior art document relevant to this invention, patent document 2 other than patent document 1 is mentioned.
JP 2002-33305 A Japanese Patent Laying-Open No. 2005-20037

  However, since nitride-based semiconductor materials have high chemical stability, it is necessary to carry out processes at very high temperatures, and appropriate mask materials cannot be easily formed. Such a conventional solution has been difficult to apply. In addition, as described above, in nitride-based materials, dislocations and defects starting from etching damage and side surface roughness can easily occur, and propagation to the inside of the crystal can easily occur. It is thought that.

  Thus, in nitride-based semiconductor materials, it has been difficult to suppress the end face damage due to dry etching and the propagation of dislocations and defects to the light-emitting region, and to eliminate adverse effects on the light-emitting characteristics and reliability.

  A semiconductor laser device according to the present invention is provided on a substrate, a first conductivity type first cladding layer provided on the first region of the substrate, and a second region adjacent to the first region of the substrate. The first conductivity type electrode formed, the active layer provided on the first region of the first cladding layer, and the second conductivity type second electrode provided on the active layer and constituting a current confinement portion. The second region of the cladding layer, which is located between the first region of the cladding layer and the second region of the substrate in plan view, has a height of the upper surface thereof. The dislocation propagation preventing region which is not more than the height of the lower surface of the active layer and higher than the height of the upper surface of the second region of the substrate, and the current confinement portion and the dislocation propagation preventing region are in plan view, It is characterized by being spaced apart from each other.

  In the method of manufacturing a semiconductor laser device according to the present invention, a first cladding layer forming step of forming a first cladding layer of a first conductivity type on a substrate, and an active layer is formed on the first cladding layer. An active layer forming step, a second cladding layer forming step of forming a second conductivity type second cladding layer constituting a current confinement portion on the active layer, and the second cladding layer forming step, Among the first etching step of etching a part of the active layer until the first cladding layer is exposed, and among the exposed regions of the first cladding layer exposed in the first etching step, in the first etching step Preventing dislocation propagation in the adjacent region by etching the exposed region until the substrate is exposed, leaving an adjacent region adjacent to the active layer left unetched in plan view. A second etching step of forming a region; and an electrode forming step of forming the first conductivity type electrode on the region of the substrate exposed in the second etching step, wherein the second cladding layer forming step includes: Is characterized in that the current confinement portion is formed in a region spaced apart in plan view from the dislocation propagation preventing region formed in the second etching step.

  In these semiconductor laser devices and manufacturing methods thereof, it is possible to reduce direct damage to the etching end face due to long-time dry etching. Even if dislocations or defects are generated on the end face due to etching, most of the propagation path to the light emitting region in the active layer is divided by the dislocation propagation preventing region, so that the dislocation or defect light emitting region enters the light emitting region. Thus, a semiconductor laser device having good element characteristics and reliability and a method for manufacturing the same can be realized.

  According to the present invention, a semiconductor laser device having good element characteristics and reliability and a manufacturing method thereof are realized.

  Hereinafter, preferred embodiments of a semiconductor laser device and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a cross-sectional view showing a first embodiment of a semiconductor laser device according to the present invention. FIG. 2 is a plan view showing the semiconductor laser device of FIG. In this embodiment, a ridge stripe type semiconductor laser device is illustrated.

  This semiconductor laser device includes a first conductivity type cladding layer 2 (first cladding layer) provided on a region R11 (first region of the substrate 1) of the substrate 1 and a region adjacent to the region R11 of the substrate 1. A first conductivity type electrode 8 provided on R12 (second region of substrate 1), an active layer 3 provided on region R21 of clad layer 2 (first region of clad layer 2), and an active layer 3 and a second conductivity type clad layer 5 (second clad layer) constituting a current confinement portion.

  Here, the height of the upper surface of the region R22 of the cladding layer 2 (second region of the cladding layer 2), which is located between the region R21 of the cladding layer 2 and the region R12 of the substrate 1 in plan view, is the active layer. 3 is a dislocation propagation preventing region that is equal to or lower than the height of the lower surface of 3 and higher than the height of the upper surface of the region R12 of the substrate 1. Further, the current confinement part and the dislocation propagation preventing region are separated from each other in plan view. The interval L2 between these current confinement portions and the dislocation propagation preventing region is preferably 5 μm or more. The width L1 of the dislocation propagation preventing region is preferably 2.3 μm or more. The reason will be described later.

  The clad layer 5 and the contact layer 6 provided thereon are processed into a ridge stripe shape, and this ridge stripe (portion indicated by an arrow A1 in the figure) functions as the above-described current constriction portion. The ridge stripe also functions as a horizontal refractive index waveguide. The width of the ridge stripe is 1.5 μm, for example.

  Thus, in the present embodiment, the current confinement portion has a ridge shape extending along the boundary between the region R21 and the region R22 of the cladding layer 2. Further, as can be seen from FIG. 2, the dislocation propagation preventing region (region R22) extends along the current confinement portion, and the dislocation propagation preventing region and the current confinement portion have a length in the extending direction. Almost equal.

  In the active layer 3, a region (a region indicated by an arrow A2 in the drawing) located below the ridge stripe is a light emitting region. The active layer 3 also functions as an optical waveguide layer. A second conductivity type electrode 7 is formed on the ridge stripe. Further, the surface of the semiconductor laser device is covered with an insulating film 12 except for the portion where the ridge stripe or electrode 8 is provided.

  The substrate 1, the clad layer 2, the active layer 3, the clad layer 5 and the contact layer 6 are, for example, an n-type GaN substrate, an n-type AlGaN clad layer, an InGaN / GaN multiple quantum well active layer, and a p-type AlGaN clad layer, respectively. And a p-type GaN contact layer. That is, in this example, the first conductivity type is n-type, and the second conductivity type is p-type.

With reference to FIGS. 3 to 7, an example of a method of manufacturing the semiconductor laser device shown in FIGS. 1 and 2 will be described as an embodiment of the method of manufacturing the semiconductor laser device according to the present invention. This manufacturing method generally includes the following steps (a) to (f).
(A) First clad layer forming step of forming the clad layer 2 on the substrate 1 (b) Active layer forming step of forming the active layer 3 on the clad layer 2 (c) Constructing a current confinement portion on the active layer 3 After the second cladding layer forming step (d) step (c) for forming the cladding layer 5 to be performed, a first etching step (e) step (d) in which a part of the active layer 3 is etched until the cladding layer 2 is exposed. In the exposed region of the cladding layer 2 exposed in step (d), the adjacent region adjacent to the active layer 3 not etched in step (d) is left in plan view, and the exposed region is etched until the substrate 1 is exposed. Then, the second etching step (f) for forming the dislocation propagation preventing region in the adjacent region (f) The electrode forming step for forming the electrode 8 on the region of the substrate 1 exposed in the step (e)

  However, in the step (c), the current confinement portion is formed in a region separated from the dislocation propagation preventing region formed in the step (e) in plan view. In one or both of the step (d) and the step (e), it is preferable to control the etching depth using an etching end point detection monitor.

  More specifically, first, the cladding layer 2, the active layer 3, the cladding layer 5, and the contact layer 6 are sequentially stacked on the substrate 1 by using a metal organic chemical vapor deposition method (MOVPE method) or the like (FIG. 3). ).

  Next, a stripe-shaped etching mask M1 having a width of, for example, about 1.5 μm is formed using a normal photolithography process. Thereafter, etching is performed partway through the cladding layer 5 by, for example, dry etching using a chlorine-based gas. Thereby, a ridge stripe is formed. The value of the ridge width and the etching depth of the cladding layer 5 affect the current-light output characteristics and current-voltage characteristics as well as the horizontal transverse mode characteristics of the semiconductor laser device. In consideration of this, it is preferable to select an optimum value (FIG. 4).

  Next, after removing the etching mask M1, a stripe-shaped etching mask M2 having a width wider than the ridge stripe is formed using a normal photolithography process. Subsequently, the active layer 3 is etched by chlorine-based dry etching until the cladding layer 2 is exposed (FIG. 5).

  Next, after removing the etching mask M2, a stripe-shaped etching mask M3 having an opening having a width narrower than the opening of the etching mask M2 is formed using a normal photolithography process. Subsequently, the cladding layer 2 is etched by chlorine-based dry etching until the substrate 1 is exposed. The exposed surface becomes the n-type electrode forming surface. In addition, the region R22 that is etched in the process described with reference to FIG. 5 and is not etched in this process and covered with the etching mask M3 becomes a dislocation propagation preventing region (FIG. 6).

  Next, after removing the etching mask M3, an insulating film 12 such as a silicon oxide film is formed on the entire surface by CVD or the like. Subsequently, the insulating film 12 in the portion where the electrode 8 and the electrode 7 are formed is removed by using a normal photolithography process. Thereafter, gold and nickel are vapor-deposited as the electrode 8, and titanium and gold are vapor-deposited as the electrode 7, and the alloy 7 is heated and heated under appropriate conditions, whereby the electrode 7 and the electrode 8 are formed. Subsequently, the laser mirror end face is formed by cleavage to obtain a semiconductor laser device (FIG. 7).

  Here, referring to FIGS. 8 and 9, the details of the structure of the etching regions (region R12 and region R22 in FIG. 1) formed in the steps (d) and (e), and the etching end face according to the present invention are described. The effect of reducing the deterioration of the light emitting region due to the damaged layer will be described. FIG. 8 schematically shows a cross-sectional structure in the vicinity of the etching region in the ridge stripe semiconductor laser device according to this embodiment shown in FIG. FIG. 9 shows a similar portion of the conventional ridge stripe semiconductor laser device shown in FIG. These drawings are schematically shown to explain the effect, and do not accurately represent the actual size, damage layer, and dislocation state.

  First, the light emitting region deterioration mechanism caused by the damaged layer on the etching end face will be described with reference to FIG. In the conventional semiconductor laser device shown in FIG. 9, the etching region is formed by one dry etching. Since the etching depth is as deep as several μm, an etching damage layer is formed on the etching end face. In the ridge stripe type semiconductor laser as shown in FIG. 9, the current confinement structure is formed by the ridge stripe, so the light emitting region in the active layer has a width substantially the same as the ridge stripe width although there is a slight current spread. It has become an area. Therefore, it is considered that the light emission characteristics and reliability of the element deteriorate due to crystal defects and dislocations entering this region. In the structure of FIG. 9, since the etching end face and the light emitting region are sufficiently separated from each other, it is considered that the damage layer generated by the etching has little influence on directly deteriorating the light emitting characteristics. A problem with this structure is the propagation of dislocations and defects to the light-emitting region, which originates from the damaged layer on the etching end face. Dislocation propagation can occur due to high temperature processes, current conduction, and the like.

  As described above, in the case of GaN or AlGaN that does not contain In, dislocations generated on the etching end face tend to propagate basically in a direction perpendicular to the substrate, but if there is an InGaN layer, the propagation direction tends to be bent horizontally. There is a feature. Therefore, dislocations generated in the damaged layer on the etching end face propagate in a direction close to vertical until reaching the InGaN active layer. However, since the GaN and AlGaN layers can also propagate in the horizontal direction triggered by defects inside the crystal, heterointerfaces, etc., as shown by arrows A3 in FIG. The distribution of the angle formed by the straight line connecting the points reaching the layer and the substrate surface is considered to have a tendency to concentrate in a direction of a certain angle θ1 or more. In this way, dislocations that reach the InGaN layer in the active layer may travel substantially horizontally in the InGaN layer, reach the light emitting region, and deteriorate the light emission characteristics. In the figure, the propagation path of dislocation is projected on the paper and simplified and shown as a straight line, but in reality, it propagates along a complicated path.

  Next, the effect of the present invention will be described with reference to FIG. Here, in this structure, the end surface on the ridge stripe side of the etching region has a two-stage structure formed by two dry etching steps, and an active layer is formed at the end of the etching region on the ridge stripe side. It is characterized by the presence of the removed dislocation propagation prevention region. With this structure, the influence of the etching damage layer on the end face can be reduced, and the propagation of dislocations / defects to the active layer light-emitting region due to the end face damage or the like can be prevented. In the first etching for forming the dislocation propagation preventing region by exposing the etching bottom surface S1, it is sufficient that at least the active layer is removed, and the depth is preferably as shallow as possible. Therefore, in step (d) of the above manufacturing method, etching is performed using a method such as monitoring the intensity of reflected light from the etching surface in order to reliably remove the active layer and stop etching immediately below the active layer. It is preferable to perform end point detection. The damage layer D1 generated in the first etching is considered to have a very small damage depth and almost no dislocations or defects due to the very small etching depth. However, if the etching end face is too close to the ridge stripe end face, the refractive index waveguide structure is affected and the transverse mode characteristics may be deteriorated. Therefore, it is necessary to charge and separate from the light emitting region. The distance L2 between the etching end face of the dislocation propagation preventing region and the ridge stripe end face is preferably secured at least about 5 μm, for example.

  In the second etching for exposing the etching bottom surface S2, it is necessary to etch several μm to the lower part of the cladding layer 2, so that a certain damage layer D2 is formed on the etching end face. As in the case of the conventional example of FIG. 9, the damage layer D2 is considered to cause dislocations to propagate in a direction of an angle θ1 or more as indicated by an arrow A3 in the drawing. However, in this structure, since the InGaN layer where these dislocations arrive is removed, they reach the crystal surface as they are, and the propagation stops. Therefore, it is possible to prevent these dislocations from entering the light emitting region in the active layer and deteriorating the light emission characteristics. Such a dislocation propagation preventing region must be provided at least between the ridge stripe and the n-type electrode formation surface. Also, in the structure before element isolation, when the InGaN active layer outside the n-type electrode formation surface continues with the light emitting region of the adjacent element, dislocation propagation prevention is also performed between the adjacent ridge stripes. It is necessary to provide an area.

Here, by determining the structure of the etching region in consideration of the propagation path of dislocation in more detail, the effect of preventing propagation of dislocation to the light emitting region can be obtained to the maximum extent. As shown in FIG. 8, in order to avoid dislocations propagating from the damaged layer on the etching end face from reaching the InGaN layer, the distance between the first etching end face and the second etching end face, ie, dislocation propagation prevention is prevented. Using the second etching depth, that is, the height difference H1 between the etching bottom surface S1 and the etching bottom surface S2, and the dislocation propagation direction θ1, a value satisfying the following equation: I understand that it should be.
L1> (H1 / tanθ1)

According to the study by the present inventors, it has been found that most of such dislocations (about 80%) follow a propagation path in which the angle θ1 from the substrate surface is about 60 ° or more. Therefore, in order to avoid most of such dislocations from reaching the active layer, L1 is L1> (H1 / tan 60 °)
By satisfying the above, a great effect can be obtained. For example, when the thickness of the n-type AlGaN cladding layer 2 is about 3 μm, if the etching depth is about 4 μm including the tolerance, L1 is preferably about 2.3 μm or more. Further, it has been found that most of such dislocations (95% or more) follow a propagation path in which the angle θ1 from the substrate surface is about 20 ° or more. Therefore, in order to avoid most of such dislocations from reaching the active layer, L1 is L1> (H1 / tan20 °).
It is desirable to satisfy. For example, when the thickness of the n-type AlGaN cladding layer 2 is 3 μm, the size of L1 is preferably 11 μm or more, and the influence of damage from the etching end face can be substantially eliminated. However, it cannot be said that there are exceptionally no dislocations propagating at an angle of 20 ° or less due to a structure such as a defect in the crystal, and it can be said that the longer L1 is, the more effective. However, if this is too long, the distance between adjacent elements must be increased, and the area per element increases and the number of elements per wafer decreases, which is problematic in productivity. In some cases, there is a concern about an increase in the resistance component that flows horizontally through the n-side cladding layer, so it is necessary to set the value appropriately. About the etching depth of the 2nd time, a suitable depth can be employ | adopted according to a condition. In the present embodiment, a part of the n-type GaN layer is an n-type electrode formation surface, but is not particularly limited, and may be a part of an n-type AlGaN cladding layer, and an n-type GaN contact layer is provided to form an n-type electrode. It is good also as an electrode formation surface. The etching depth may be changed in accordance with each situation, but a smaller one is more efficient because it is not necessary to increase the length of L1.

  In the semiconductor laser device of FIG. 1 obtained by the above manufacturing method, it is possible to suppress the deterioration of the crystal due to dislocation propagation caused by the damage of the etching end face due to the dry etching. As described above, in this embodiment, even in a device structure that requires dry etching to a position deeper than the active layer (for example, a semiconductor laser element structure having both positive and negative electrodes on the same surface of the substrate), dry etching is performed. A nitride-based semiconductor laser element that suppresses the introduction of defects into the active layer due to the above and has excellent device characteristics and reliability has been realized.

(Second Embodiment)
FIG. 10 is a plan view showing a second embodiment of the semiconductor laser device according to the present invention. In this embodiment, a manufacturing method similar to that described with reference to FIGS. 3 to 7 is adopted, but the planar shape of the etching region formed by two dry etchings is a closed shape in the element. There are some differences. That is, the dislocation propagation preventing region has a shape constituted by a closed straight line or curve in plan view.

  Such a configuration is advantageous for forming a cleavage plane in the semiconductor laser device. Since nitride-based materials are very hard, it is relatively difficult to obtain a cleavage plane with high flatness as compared with conventional InP-based and GaAs-based materials. In this regard, in the structure shown in FIGS. 1 and 2, since the structure on both sides of the stripe on the cleavage plane is asymmetric, extra force is applied to the ridge stripe portion, and the flatness of the cleavage plane may be deteriorated. is there. On the other hand, in the present embodiment, the structure of the cross section along the dotted line C1 is the same as the cross section shown in FIG. 1, but the structures near both sides of the stripe are symmetrical on the cleavage plane along the dotted lines C2 and C3. Therefore, it is possible to obtain a cleavage plane with high flatness.

  In this case, in the etching region, for example, as shown in FIG. 10, it is preferable to provide a dislocation propagation preventing region (region R22) also on the end face perpendicular to the stripe. This is also because dislocations due to damage or the like at the end face of the end face perpendicular to the stripe may propagate to the light emitting region in the stripe of the adjacent element in the wafer state before cleavage.

  The semiconductor laser device and the manufacturing method thereof according to the present invention are not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the semiconductor laser device on the n-type GaN substrate is taken as an example, but a semiconductor laser device on a substrate other than the GaN substrate such as a sapphire substrate or a silicon substrate may be used. In the case where the substrate is not conductive, n-type layers can be stacked to form an n-type electrode contact layer, which can take the same form. In the above-described embodiment, the ridge stripe type semiconductor laser structure has been described. However, the present invention is not particularly limited to such a structure, and the inner stripe type semiconductor laser device and the mesa type light emitting device are used. The present invention can be applied to any structure as long as it is a light emitting element / light receiving element having electrodes on the same surface, such as a diode element and a surface emitting laser element.

  In addition, here, the problem in the case where both positive and negative electrodes are formed on the surface has been described. However, when etching is required to a certain distance from the current injection region of the active layer to below the active layer, for example, etching laser Also when performing processes such as end face formation and element separation by etching, etching is performed in two steps in the same manner as in the present invention, and by adopting a structure in which a dislocation propagation prevention region is provided, dislocations generated on the etching end face are eliminated. Propagation to the light emitting region can be suppressed.

  Further, the cross-sectional shape and the planar shape of the etching region and the dislocation propagation preventing region can be appropriately selected as long as the structure is based on the gist of the present invention. Further, although the embodiment in which the dislocation propagation preventing region is formed by dry etching has been described here, the dislocation propagation preventing region is formed by forming a stacked structure so that the active layer is not formed in advance by using a selective growth method or the like. May be. It goes without saying that the material and film thickness of each layer structure can be selected and set as appropriate.

  In each embodiment, the n-type may be changed to the p-type and the p-type may be changed to the n-type.

  Further, the semiconductor laser device according to the present invention can be used for a light source for a next-generation high-density optical disk, a white light source, or the like.

1 is a cross-sectional view showing a first embodiment of a semiconductor laser device according to the present invention. It is a top view which shows the semiconductor laser apparatus of FIG. It is process drawing which shows one Embodiment of the manufacturing method of the semiconductor laser apparatus by this invention. It is process drawing which shows one Embodiment of the manufacturing method of the semiconductor laser apparatus by this invention. It is process drawing which shows one Embodiment of the manufacturing method of the semiconductor laser apparatus by this invention. It is process drawing which shows one Embodiment of the manufacturing method of the semiconductor laser apparatus by this invention. It is process drawing which shows one Embodiment of the manufacturing method of the semiconductor laser apparatus by this invention. It is sectional drawing for demonstrating the effect of this invention. It is sectional drawing for demonstrating the effect of this invention. It is a top view which shows 2nd Embodiment of the semiconductor laser apparatus by this invention. 1 is a cross-sectional view showing a general ridge stripe type nitride semiconductor laser device having positive and negative electrodes on the same surface side of a substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Clad layer 3 Active layer 5 Clad layer 6 Contact layer 7 Electrode 8 Electrode 12 Insulating film

Claims (11)

A substrate,
A first conductivity type first cladding layer provided on a first region of the substrate;
An electrode of the first conductivity type provided on a second region adjacent to the first region of the substrate;
An active layer provided on a first region of the first cladding layer;
A second clad layer of a second conductivity type provided on the active layer and constituting a current confinement portion,
The height of the upper surface of the second region of the first cladding layer, which is located between the first region of the first cladding layer and the second region of the substrate in plan view, is the active layer. A dislocation propagation preventing region that is equal to or lower than the height of the lower surface of the substrate and higher than the height of the upper surface of the second region of the substrate,
The semiconductor laser device, wherein the current confinement part and the dislocation propagation prevention region are separated from each other in plan view. The semiconductor laser device according to claim 1,
The semiconductor laser device, wherein the current confinement portion and the dislocation propagation prevention region are separated from each other by 5 μm or more in plan view. The semiconductor laser device according to claim 1 or 2,
The semiconductor laser device, wherein the current confinement portion has a ridge shape extending along a boundary between the first and second regions of the first cladding layer. The semiconductor laser device according to claim 3,
The dislocation propagation preventing region extends along the current constriction,
The dislocation propagation preventing region and the current confinement portion are semiconductor laser devices having substantially the same length in the extending direction. The semiconductor laser device according to claim 3,
The dislocation propagation preventing region is a semiconductor laser device having a shape constituted by a closed straight line or curve in a plan view. The semiconductor laser device according to any one of claims 1 to 5,
The distance in plan view between the first region of the first cladding layer and the second region of the substrate is L1, the height of the upper surface of the dislocation propagation preventing region and the upper surface of the second region of the substrate A semiconductor laser device in which L1> (H1 / tan 60 °) is satisfied, where H1 is the difference from the height. The semiconductor laser device according to claim 6, wherein
A semiconductor laser device satisfying L1> (H1 / tan20 °). The semiconductor laser device according to claim 1,
The substrate is a GaN substrate;
The semiconductor laser device, wherein the active layer includes an InGaN layer. The semiconductor laser device according to claim 1,
The semiconductor laser device, wherein the first conductivity type is n-type and the second conductivity type is p-type. A first cladding layer forming step of forming a first conductivity type first cladding layer on a substrate;
An active layer forming step of forming an active layer on the first cladding layer;
A second clad layer forming step of forming a second clad layer of a second conductivity type constituting a current confinement portion on the active layer;
A first etching step of etching a part of the active layer until the first cladding layer is exposed after the second cladding layer forming step;
Of the exposed region of the first cladding layer exposed in the first etching step, the exposed region leaves an adjacent region adjacent in plan view to the active layer left unetched in the first etching step. A second etching step of forming a dislocation propagation preventing region in the adjacent region by etching until the substrate is exposed;
Forming an electrode of the first conductivity type on a region of the substrate exposed in the second etching step, and
In the second clad layer forming step, the current confinement portion is formed in a region separated in plan view from the dislocation propagation preventing region formed in the second etching step. Method. In the manufacturing method of the semiconductor laser device according to claim 10,
A method of manufacturing a semiconductor laser device, wherein an etching depth is controlled using an etching end point detection monitor in one or both of the first and second etching steps.

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