JP2006100369A - Semiconductor laser device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser element having reduced characteristics of strain efficiency and the like by reducing variation in strain stress of an electrode layer.
A barrier metal layer 35 made of a material difficult to be alloyed with solder 56 is interposed between a thick film electrode layer 34 and a bonding metal layer 36. The thickness of the barrier metal layer 35 is selected as the fifth thickness T5, and the thickness of the bonding metal layer 36 is selected as the sixth thickness T6. Therefore, when the semiconductor laser element 1 is connected to the body 55 to be connected by the solder 56, the alloying reaction between the material forming the first electrode portion 3 </ b> A and the solder 56 stops at the barrier metal layer 34. Further, the alloying reaction occurs uniformly in the entire bonding metal layer between the solder 56 and the barrier metal layer 35. Therefore, the stress applied to the thick film electrode layer 34 by the alloy generated in the barrier metal layer 35 is uniform, so that variation in strain stress of the thick film electrode layer 34 can be reduced, and characteristics such as slope efficiency can be reduced. It becomes a good semiconductor laser element.
[Selection] Figure 1

Description

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

  A semiconductor laser device of the prior art includes a first clad layer made of AlGaAs of the same conductivity type as a substrate on one surface of a substrate made of p-type GaAs or n-type GaAs, an active layer made of AlGaAs thereon, and A semiconductor layer formed by laminating a second clad layer made of AlGaAs of a different conductivity type from the first clad layer and a contact layer made of GaAs of the same conductivity type as the second clad layer thereon; And an ohmic contact electrode layer for making ohmic contact on one surface of the contact layer, a contact mediating layer thereon, and an electrode formed by laminating an electrode layer as a bonding metal thereon . The ohmic contact electrode layer is made of AuZn if the contact layer has a P-type conductivity, or AuGeNi if the contact type of the semiconductor layer is an N-type. After forming the ohmic contact electrode layer, the ohmic contact electrode layer is alloyed with the contact layer in an alloy process at 400 to 450 ° C. in order to make an ohmic contact. When the ohmic contact electrode layer and the electrode layer are brought into direct contact without going through the contact mediating layer, the adhesion between the two is poor, and the ohmic contact electrode layer and the electrode layer are easily peeled off. Therefore, a contact mediating layer made of, for example, titanium is interposed between the ohmic contact electrode layer and the electrode layer (see, for example, Patent Document 1).

  When such a semiconductor laser element is fused to a heat sink or a package by soldering, the material for forming the electrode layer and the solder are alloyed to form a reaction layer of the material for forming the electrode layer and the solder. Further, the material forming the electrode layer and the solder are alloyed even at the temperature when the semiconductor laser element is energized. Therefore, when the temperature of the semiconductor laser element rises by using the semiconductor laser element for a long time, the material forming the electrode layer and the solder are alloyed, and the reaction layer is expanded. Since the reaction layer has a considerably lower thermal conductivity than the electrode layer, if the reaction layer is thick, the heat dissipation effect by the electrode portion is significantly impaired. In addition, since the reaction layer has a hardness higher than that of the electrode layer, the stress applied to the semiconductor layer by the reaction layer increases as the thickness of the reaction layer increases. Therefore, as the reaction layer becomes thicker, the reliability of the semiconductor laser device is significantly reduced.

  In view of such a problem, another conventional semiconductor laser device is connected to the barrier metal layer on the electrode layer of the above-described conventional semiconductor laser device, and connected to the connected body on the barrier metal layer. Some have an electrode formed by laminating a bonding metal layer. This electrode layer is laminated by a plating method. By providing a barrier metal layer that is difficult to alloy with solder between the bonding metal layer and the electrode layer, the progress of the alloying reaction between the material forming the bonding metal layer and the solder can be stopped by the barrier metal layer. The thickness of the reaction layer can be reduced. By reducing the thickness of the reaction layer, it is possible to reduce the thermal conductivity of the electrode portion due to the reaction layer and the stress applied to the semiconductor layer by the reaction layer (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-54843 JP 59-165474 A

  Variations in the strain stress of the electrodes of the semiconductor laser element may affect the characteristics of the semiconductor laser. For example, when there is a variation in the strain stress of the electrode, the light emission angle may be disturbed. For example, there is a problem that the light intensity does not change smoothly when viewed from a direction horizontal to the surface of the active layer. In addition, the electrode may exert stress on the active layer of the semiconductor laser element, and transition may occur in the active layer. In a place where there is a transition, even if the semiconductor laser element is energized, non-radiative recombination is caused, a large amount of heat is generated, and no light is emitted. In addition, the transition spreads in the active layer centering on the transition generated in the active layer due to the heat generated by energizing the semiconductor laser element. Therefore, when the semiconductor laser element is continuously energized, the transition grows around the transition generated in the active layer, and finally the semiconductor laser element does not oscillate. Therefore, when a transition occurs in the active layer due to variations in the strain stress of the electrodes, the characteristics of the semiconductor laser element deteriorate, such as a decrease in slope efficiency, a decrease in light emission efficiency, an increase in threshold current, and a decrease in lifetime of the semiconductor laser element. To do.

  In the conventional technique described above, a barrier metal layer made of a material that does not easily react with solder is provided between the bonding metal layer and the electrode layer, thereby reducing the thickness of the reaction layer, and stress applied to the semiconductor layer by the reaction layer. Reduced. However, since the range in which the reaction layer is formed is difficult to control, the strain stress of the electrode layer varies depending on the range in which the reaction layer is formed. In the prior art, the variation in strain stress of the electrode layer cannot be reduced. Therefore, the variation in strain stress of the electrode layer deteriorates the characteristics of the semiconductor laser such as slope efficiency, light emission efficiency, lifetime, and threshold current. .

  Accordingly, an object of the present invention is to provide a semiconductor laser device having good characteristics by reducing variations in strain stress of an electrode layer.

The present invention is provided on a surface of a semiconductor substrate, a light emitting layer formed by laminating a semiconductor layer on one surface of the semiconductor substrate, and a surface of the light emitting layer on one side in the stacking direction of the semiconductor layer. A semiconductor laser element including an electrode portion connected to the body by solder,
The electrode part
An electrode layer provided near the light emitting layer;
A barrier metal layer that is laminated on the surface of the electrode layer opposite to the light emitting layer and prevents a compound of the material forming the electrode layer and the solder from being formed by the solder;
The barrier metal layer is laminated on the surface opposite to the electrode layer, and has a bonding metal layer connected to the connected body,
The light emitting layer has an active layer,
The shortest distance between the electrode layer and the active layer is selected from 0.05 μm to 3 μm,
A thickness of the electrode layer is selected from 0.5 μm to 5 μm.

  According to the present invention, a barrier metal layer that prevents a compound of the material forming the electrode layer and the solder from being formed by solder is interposed between the electrode layer and the bonding metal layer. When the electrode part is connected to the body to be connected by solder, the material forming the bonding metal layer and the solder are alloyed. The alloying reaction proceeds from the contact surface between the bonding metal layer and the solder toward the electrode layer. Since the material forming the barrier metal layer and the solder are not easily alloyed, the progress of the alloying reaction can be stopped by the barrier metal layer. The alloy of the material forming the bonding metal layer and the solder has higher hardness and higher strain stress than the material forming the bonding metal layer. Therefore, when the electrode portion is connected to the body to be connected by solder, if a portion to be alloyed and a portion not to be alloyed are formed in the bonding metal layer, variations in strain stress occur in the bonding metal layer. Therefore, the entire bonding metal layer is alloyed by setting the temperature of the solder connecting the electrode part to the connected body to a predetermined temperature. At this time, since the progress of the alloying reaction between the material forming the bonding metal layer and the solder can be stopped by the barrier metal layer, the electrode layer is not alloyed. Since the entire bonding metal layer is formed only of an alloy with solder, variation in strain stress of the bonding metal layer can be reduced. When the strain stress of the bonding metal layer is applied to the electrode layer, the stress stress is generated in the electrode layer. By reducing the variation of the strain stress of the bonding metal layer, the variation of the strain stress generated in the electrode layer is reduced. Can do.

  The thickness of the electrode layer is selected from 0.5 μm to 5 μm. When the thickness of the electrode layer is less than 0.5 μm, the heat dissipation effect by the electrode layer is small, and heat generated in the active layer when the semiconductor laser element is energized cannot be efficiently dissipated through the electrode layer. Further, when the thickness of the electrode layer exceeds 5 μm, the strain stress of the electrode layer and the variation of the strain stress of the electrode layer increase. For this reason, the stress applied to the light emitting layer by the electrode layer increases, and the radiation angle of the laser beam may be disturbed. Therefore, when the thickness of the electrode layer is selected to be 0.5 μm or more and 5 μm or less, it is possible to form an electrode layer having a large heat dissipation effect and a small variation in strain stress.

  The shortest distance between the electrode layer and the active layer is selected to be 0.05 μm or more and 3 μm or less. When the shortest distance between the electrode layer and the active layer is less than 0.05 μm and the electrode layer and the active layer are too close to each other, the stress applied by the electrode layer to the light emitting layer increases. For this reason, the radiation angle of the laser beam may be disturbed. Further, when the shortest distance between the electrode layer and the active layer exceeds 3 μm, the distance between the electrode layer and the active layer is increased, so that the heat generated in the active layer can be efficiently dissipated through the electrode layer. become unable. Therefore, when the shortest distance between the electrode layer and the active layer is selected to be 0.05 μm or more and 3 μm or less, a heat radiation effect by the electrode layer is large, and a semiconductor laser element in which the stress applied by the electrode layer to the light emitting layer is small.

  Further, the invention is characterized in that one surface of the light emitting layer in contact with the electrode portion is a curved surface.

  According to the present invention, since one surface of the light emitting layer in contact with the electrode portion is a curved surface, one surface of the light emitting layer can be formed to be a semiconductor laser element having a refractive index waveguide structure and a current confinement structure. it can. In addition, when one surface of the light emitting layer in contact with the electrode portion is a curved surface, stress due to variations in strain stress of the electrode layer may be locally concentrated on a specific portion of the one surface of the light emitting layer. In this case, the influence of the variation in the strain stress of the electrode layer on the light emitting layer becomes remarkable, but in the present invention, the variation in the strain stress of the electrode layer that occurs when the electrode portion is connected to the connected body by soldering is reduced. Therefore, it is possible to reduce the influence of the variation in the strain stress of the electrode layer on the light emitting layer.

In the invention, it is preferable that the electrode layer is formed by a plating method.
According to the present invention, the electrode layer is formed by a plating method. The plating method is easier to control the strain stress generated during film formation than the sputtering method. Therefore, the electrode layer formed by plating has a smaller variation in strain stress of the electrode layer than the electrode layer formed by sputtering.

  In the present invention, the thickness of the barrier metal layer is selected to be 50 nm or more and less than 1000 nm.

  According to the present invention, the thickness of the barrier metal layer is 50 nm or more and less than 1000 nm. When the electrode part is connected to the body to be connected by solder, if the thickness of the barrier metal layer is thin and less than 50 nm, the alloying reaction between the solder and the electrode part cannot be stopped by the barrier metal layer. If the thickness of the layer is large and 50 nm or more, the alloying reaction between the solder and the electrode portion can be stopped by the barrier metal layer. Moreover, if the thickness of the barrier metal layer is 1000 nm or more, the electrical resistance of the barrier metal layer increases. When the electric resistance of the barrier metal layer increases, the power consumed by the barrier metal layer out of the electric power supplied to the semiconductor laser element increases, so that the performance as the electrode portion decreases. On the other hand, if the thickness of the barrier metal layer is less than 1000 nm, the electric resistance of the barrier metal layer is small, so that an electrode part with good performance is obtained.

  According to the present invention, the barrier metal layer is formed of at least one of molybdenum, titanium, and titanium nitride.

  According to the present invention, the barrier metal layer is formed of at least one of molybdenum, titanium, and titanium nitride, which are materials that are difficult to alloy with solder. When the electrode part is connected to the body to be connected by solder, since the barrier metal layer is formed from a material that is difficult to alloy with the solder, the progress of the reaction in which the solder and the electrode part are alloyed can be stopped by the barrier metal layer. .

  In the invention, it is preferable that the barrier metal layer covers a remaining surface except one surface facing the light emitting layer of the electrode layer.

  According to the present invention, since the electrode layer is separated from the bonding metal layer by the barrier metal layer, there is no portion where the electrode layer and the bonding metal layer are in contact with each other. When there is a part where the electrode layer and the bonding metal layer are in contact, when the electrode part is connected to the body to be connected by solder, the material for forming the electrode layer and the solder are alloyed to the part where the electrode layer and the bonding metal layer are in contact There is a case. In the present invention, since the electrode layer is separated from the bonding metal layer by the barrier metal layer, the progress of the reaction in which the solder and the electrode part are alloyed stops at the barrier metal layer, so the alloy of the electrode layer and the solder is Not formed.

  In the invention, it is preferable that the electrode layer is formed in a portion excluding the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layer of the light emitting layer.

  According to the present invention, the electrode layer is not formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layers of the light emitting layer. When the electrode layer is formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the light emitting layer, for example, in the cleavage process, it is difficult to divide the electrode layer. In the present invention, since the electrode layer is not formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layer of the light emitting layer, the division failure of the semiconductor laser element due to the electrode layer occurs in the cleavage step. No longer.

  In the invention, it is preferable that the barrier metal layer is formed in a portion excluding the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layer of the light emitting layer.

  According to the present invention, the barrier metal layer is not formed on the periphery of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layers of the light emitting layer. When a barrier metal layer is formed at the peripheral edge of the light emitting layer when viewed from one side in the stacking direction of the light emitting layer, for example, in the cleavage process, it is difficult to divide the barrier metal layer. However, in the present invention, since the barrier metal layer is not formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the semiconductor layer of the light emitting layer, the division of the semiconductor laser element caused by the barrier metal layer in the cleavage step Defects will not occur.

The present invention is also a method of manufacturing a semiconductor laser device for manufacturing the semiconductor laser device,
The semiconductor laser element includes a second electrode portion provided on the other surface of the semiconductor substrate,
After forming the light emitting layer, a second electrode portion is formed, and thereafter the electrode portion is formed on one surface of the light emitting layer.

  According to the invention, the electrode part is formed after the second electrode part is formed. Even when an electrode layer having a small variation in strain stress is formed, if the temperature of the electrode layer becomes 350 ° C. or higher after the electrode layer is formed, the variation in the strain stress of the electrode layer increases due to heat applied to the electrode layer. Even when the temperature of the light emitting portion, the semiconductor substrate, and the second electrode portion is 350 ° C. or higher when forming the second electrode layer, the electrode portion is not formed. It is not affected by the temperature when forming the two-electrode layer. Therefore, it is possible to form an electrode layer with small variations in strain stress of the electrode layer.

  According to the present invention, in the step after forming the electrode layer, a semiconductor laser element is manufactured within a temperature range of 50 ° C. or higher and lower than 350 ° C.

  According to the present invention, after the electrode layer is formed, a semiconductor laser device is manufactured within a temperature range of 50 ° C. or higher and lower than 350 ° C. In the process after the electrode layer is formed, when the temperature of the electrode layer becomes less than 50 ° C. and the amount of change in the temperature of the electrode layer increases, the variation in strain stress of the electrode layer increases due to thermal stress. The stress applied to the light emitting layer is increased by increasing the variation in the strain stress of the electrode layer. For this reason, the radiation angle of the laser beam may be disturbed. Even if an electrode layer with small variations in strain stress is formed, if the temperature of the electrode layer becomes 350 ° C. or higher in the process after forming the electrode layer, the strain applied to the electrode layer varies due to the heat applied to the electrode layer. Becomes larger. The stress applied to the light emitting layer is increased by increasing the variation in the strain stress of the electrode layer. For this reason, the radiation angle of the laser beam may be disturbed. Therefore, after the electrode layer is formed, the variation of the strain stress of the electrode layer can be reduced by manufacturing the semiconductor laser element within a temperature range of 50 ° C. or higher and lower than 350 ° C.

  According to the present invention, by interposing a barrier metal layer between the electrode layer and the bonding metal layer to prevent the compound of the material forming the electrode layer and the solder from being formed by solder, the electrode layer The variation in strain stress can be reduced. Therefore, variation in characteristics of the semiconductor laser element caused by variation in strain stress of the electrode layer can be reduced, and a semiconductor laser element having good characteristics can be obtained.

  In addition, according to the present invention, an electrode layer having a large heat dissipation effect and a small variation in strain stress can be formed by selecting the thickness of the electrode layer from 0.5 μm to 5 μm. By forming an electrode layer having a large heat dissipation effect, a semiconductor laser element having good characteristics such as slope efficiency can be obtained. In addition, since an electrode layer having a small variation in strain stress can be formed, the stress applied to the light emitting layer can be reduced, and a semiconductor laser element in which the laser beam radiation angle is less likely to be disturbed can be obtained.

  According to the present invention, the shortest distance between the electrode layer and the active layer is selected to be less than 0.05 μm, so that the heat radiation effect by the electrode layer is large and the stress applied by the electrode layer to the light emitting layer is small. It becomes. By forming an electrode layer having a large heat dissipation effect, a semiconductor laser element having good characteristics such as slope efficiency can be obtained. In addition, since an electrode layer having a small variation in strain stress can be formed, the stress applied to the light emitting layer can be reduced, and a semiconductor laser element in which the laser beam radiation angle is less likely to be disturbed can be obtained.

  In addition, according to the present invention, a semiconductor laser device having a refractive index waveguide structure and a current confinement structure can be formed. In addition, when one surface of the light emitting layer is a curved surface, the strain stress of the electrode layer applied to one surface of the light emitting layer in contact with the electrode portion may be locally concentrated, and the variation of the strain stress of the electrode layer may be However, the variation in the characteristics of the semiconductor laser caused by the variation in the strain stress of the electrode layer can be reduced by reducing the variation in the strain stress of the electrode layer. Therefore, a semiconductor laser element with good characteristics can be obtained.

  In addition, according to the present invention, since the electrode layer is formed by a plating method, it is possible to reduce variations in strain stress of the electrode layer, and to reduce variations in characteristics of the semiconductor laser caused by variations in strain stress of the electrode layer. can do. Therefore, a semiconductor laser element with good characteristics can be obtained.

  According to the present invention, the thickness of the barrier metal layer is not less than 50 nm and less than 1000 nm. Since the thickness of the barrier metal layer is 50 nm or more, the progress of the alloying reaction between the solder and the electrode portion can be stopped by the barrier metal layer. Therefore, variation in strain stress of the electrode layer can be reduced, and variation in characteristics of the semiconductor laser caused by variation in strain stress of the electrode layer can be reduced. Moreover, since the thickness of the barrier metal layer is less than 1000 nm, the electrical resistance of the barrier metal layer is small, and the performance as an electrode portion does not deteriorate. Therefore, a semiconductor laser element with good characteristics can be obtained.

  Further, according to the present invention, the barrier metal layer is formed of a material that does not easily react with the solder used to connect the electrode part to the body to be connected, so that the alloying reaction between the solder and the electrode part proceeds. It can be stopped by a barrier metal layer. Therefore, variation in strain stress of the electrode layer can be reduced, and variation in characteristics of the semiconductor laser caused by variation in strain stress of the electrode layer can be reduced. Therefore, a semiconductor laser element with good characteristics can be obtained.

  According to the present invention, since the electrode layer is separated from the bonding metal layer by the barrier metal layer, the electrode layer is not alloyed with solder and the material forming the electrode layer. Therefore, variation in strain stress of the electrode layer can be reduced, and variation in characteristics of the semiconductor laser caused by variation in strain stress of the electrode layer can be reduced. Therefore, a semiconductor laser element with good characteristics can be obtained.

  Further, according to the present invention, since the electrode layer is not formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the light emitting layer, for example, the division failure of the semiconductor laser element due to the electrode layer in the cleavage step is No longer occurs. Therefore, a semiconductor laser element with good characteristics can be obtained. In addition, the yield of the semiconductor laser element is improved, and the manufacturing cost can be reduced.

  Further, according to the present invention, since the barrier metal layer is not formed on the peripheral portion of the light emitting layer when viewed from one side in the stacking direction of the light emitting layer, for example, the division failure of the semiconductor laser element due to the barrier metal layer in the cleavage step Will not occur. Therefore, a semiconductor laser element with good characteristics can be obtained. In addition, the yield of the semiconductor laser element is improved, and the manufacturing cost can be reduced.

  Further, according to the present invention, since the electrode portion is formed after the second electrode portion is formed, it is possible to reduce variations in strain stress of the electrode layer. Therefore, it is possible to reduce the variation in characteristics of the semiconductor laser caused by the variation in the strain stress of the electrode layer. Therefore, a semiconductor laser element with good characteristics can be obtained.

  In addition, according to the present invention, after forming the electrode layer, the semiconductor laser element is manufactured within a temperature range of 50 ° C. or higher and lower than 350 ° C., so that the variation in strain stress of the electrode layer can be reduced. Since an electrode layer having a small variation in strain stress can be formed, the stress applied to the light emitting layer can be reduced, and a semiconductor laser element in which the laser beam radiation angle is less likely to be disturbed can be obtained.

  FIG. 1 is a sectional view of a semiconductor laser device 1 according to an embodiment of the present invention. FIG. 2 is a simplified perspective view showing the semiconductor laser device 1. FIG. 1 is a cross-sectional view of the semiconductor laser device 1 as viewed along the section line II in FIG. The semiconductor laser device 1 includes a substrate 10, a light emitting layer 2, a first electrode portion 3A, and a second electrode portion 3B.

  The light emitting layer 2 is formed by laminating a plurality of semiconductor layers on one surface 22 in the thickness direction of the substrate 10. The first electrode portion 3 </ b> A is provided on the one surface 20 on one side in the stacking direction of the semiconductor layers of the light emitting layer 2. The second electrode portion 3B is provided on the other surface 21 in the thickness direction of the substrate 10.

The light emitting layer 2 includes a first cladding layer 11, an active layer 12, a second cladding layer 13, a first contact layer 14A, a second contact layer 14B, and a third contact layer 14C. . The light emitting layer 2 has a substantially rectangular parallelepiped shape. The laser light is emitted from a pair of opposed surfaces of the light emitting layer 2 that are parallel to the stacking direction of the semiconductor layers. This pair of surfaces is referred to as an emission surface 15. A direction perpendicular to the emission surface 15 is defined as a first direction Y, a direction perpendicular to the first direction Y and the stacking direction of the semiconductor layers is defined as a second direction X, and the stacking direction of the semiconductor layers is defined as a third direction Z. Define. One of the stacking directions of the semiconductor layers is defined as one of the third directions Z.
The substrate 10 is made of, for example, n-type GaAs.

  The first cladding layer 11 is laminated so as to cover the one surface 22 in the thickness direction of the substrate 10. The active layer 12 is laminated so as to cover the one surface 24 in the thickness direction of the first cladding layer 11. The second cladding layer 13 is laminated so as to cover the one surface 25 in the thickness direction of the active layer 12. The first contact layer 14 </ b> A is formed at the central portion in the second direction X on the one surface 26 in the thickness direction of the second cladding layer 13. The second contact layer 14 </ b> B is formed at one end in the second direction X on the one surface 26 in the thickness direction of the second cladding layer 13. The third contact layer 14 </ b> C is formed at the other end portion in the second direction X on the one surface 26 in the thickness direction of the second cladding layer 13. The first contact layer 14A, the second contact layer 14B, and the third contact layer 14C extend between both end portions in the first direction Y of the light emitting layer 2. The first contact layer 14A, the second contact layer 14B, and the third contact layer have a substantially rectangular parallelepiped shape. The opposing surfaces of the first contact layer 14A and the second contact layer 14B are separated by a predetermined distance L. The opposing surfaces of the first contact layer 14A and the third contact layer 14C are separated by a predetermined distance L. The distance L is selected from 5 μm to 200 μm, for example.

  The first cladding layer 11 is made of, for example, n-type AlGaAs. The active layer 12 is made of, for example, AlGaAs. The second cladding layer 13 is made of, for example, p-type AlGaAs. The first contact layer 14A, the second contact layer 14B, and the third contact layer 14C are made of, for example, p-type GaAs.

  The first electrode portion 3A includes an oxide film 30, a first ohmic contact electrode layer 31, a first contact mediating layer 32, a thin film electrode layer 33, a thick film electrode layer 34, a barrier metal layer 35, and a bonding metal. Layer 36.

  The oxide film 30 is formed to cover the one surface 40 on one side in the third direction Z of the second contact layer 14B and the one surface 41 on one side in the third direction Z of the third contact layer 14C. Further, the oxide film 30 does not contact the first contact layer 14A, the second contact layer 14B, and the third contact layer 14C on the one surface 43 on the one side in the third direction Z of the second cladding layer 13. Formed over the part. The first ohmic contact electrode layer 31 is laminated so as to cover the one surface 44 on one side in the third direction Z of the oxide film 30 and the one surface 42 on one side in the third direction Z of the first contact layer 14A. The first contact mediating layer 32 is laminated so as to cover the one surface 45 on the one side in the third direction Z of the first ohmic contact electrode layer 31. The thin film electrode layer 33 is laminated so as to cover the one surface 46 on the one side in the third direction Z of the first contact mediating layer 32. The thick film electrode layer 34 is located on one surface 47 on one side in the third direction Z of the thin film electrode layer 33 from the periphery of the light emitting layer 2 to the predetermined tenth distance U1 when viewed from the one side in the third direction Z. It is laminated so as to cover a portion excluding the peripheral portion. The barrier metal layer 35 is laminated so as to cover the one surface 48 on one side in the third direction Z of the thick film electrode layer 34. Furthermore, the barrier metal layer 35 is a portion that does not contact the thick film electrode layer 34 on the one surface 47 on one side in the third direction Z of the thin film electrode layer 33 and is seen from one side in the third direction Z. The light emitting layer 2 is laminated so as to cover a portion excluding the peripheral edge from the peripheral edge of the light emitting layer 2 to a predetermined eleventh distance U2. The bonding metal layer 36 includes the barrier metal layer 35 and the thick film on the one surface 49 on one side in the third direction Z of the barrier metal layer 35 and on the one surface 47 on one side in the third direction Z of the thin film electrode layer 33. A portion that does not contact the electrode layer 34 is laminated.

  Since the first contact layer 14A, the second contact layer 14B, and the third contact layer 14C have the above-described shape, the first electrode portion 3A has one surface in the third direction Z on one side in the third direction Z side. , A groove extending in the third direction Z from one side to the other is formed between the first contact layer 14A and the second contact layer 14B and between the first contact layer 14A and the third contact layer 14C. .

  The first ohmic contact electrode layer 31 and the first contact layer 14A are in ohmic contact. When the first ohmic contact electrode layer 31 and the thin film electrode layer 33 are directly laminated, the first ohmic contact electrode layer 31 and the thin film electrode layer 33 have poor adhesion and are easily peeled off. The first contact medium layer 32 is interposed between the thin film electrode layer 31 and the thin film electrode layer 33 to improve the adhesion of the first electrode portion 3A. In addition, when the semiconductor laser element 1 is energized, no current flows through the oxide film 30 and current flows from the first electrode portion 3A through one surface in the third direction Z of the first contact layer 14A. . As a result, current can be collected in the central portion of the active layer 12 in the second direction X, so that the semiconductor laser device 1 has a current confinement structure.

  The first ohmic contact electrode layer 31 is made of, for example, AuZn. The first contact mediating layer 32 is made of, for example, titanium (Ti). The thin film electrode layer 33 is made of, for example, gold (Au). The thick film electrode layer 34 is made of, for example, Au. The barrier metal layer 35 is a material that is difficult to alloy with solder, and is made of at least one of molybdenum (Mo), titanium (Ti), and titanium nitride (TiN). The bonding metal layer 36 is made of, for example, Au.

  The first ohmic contact electrode layer 31 has a first thickness T1. The first contact mediating layer 32 has a second thickness T2. The thin film electrode layer 33 has a third thickness T3. The thick film electrode layer 34 has a fourth thickness T4. The barrier metal layer 35 has a fifth thickness T5. The bonding metal layer 36 has a sixth thickness T6. Here, the thickness of the layer is defined as follows. When there are two adjacent layers, the thickness of the layer is the shortest distance between one surface in contact with one adjacent layer and the other surface in contact with the other adjacent layer. When there is one adjacent layer, the thickness of the layer is the shortest distance between one surface in contact with the adjacent layer and the other surface opposite to the surface.

  The first thickness T1 described above is selected to be, for example, 50 to 200 nm. The aforementioned second thickness T2 is selected, for example, from 100 to 200 nm. The above-described third thickness T3 is selected to be 100 to 500 nm, for example. The aforementioned fourth thickness T4 is selected to be, for example, 1 to 5 μm. The above-described fifth thickness T5 is selected to be, for example, 100 to 200 nm. The aforementioned sixth thickness T6 is selected to be 300 to 500 nm, for example. The aforementioned tenth distance U1 is selected, for example, from 5 μm to 50 μm. The aforementioned eleventh distance U2 is selected to be 5 μm to 50 μm, for example.

  The second electrode portion 3B includes a second ohmic contact electrode layer 50, a second contact mediating layer 51, and a substrate side electrode layer 52.

  The second ohmic contact electrode layer 50 is laminated so as to cover the other surface 21 on the other side in the third direction Z of the substrate 10. The second contact medium layer 51 is laminated so as to cover the other surface 53 on the other side in the third direction Z of the second ohmic contact electrode layer 50. The substrate-side electrode layer 52 is laminated so as to cover the other surface 54 of the second contact mediating layer 51 in the third direction Z on the other side.

  The second ohmic contact electrode layer 50 is made of, for example, AuGeNi. The second contact mediating layer 51 is made of Ti, for example. The substrate side electrode layer 52 is made of, for example, Au.

  The second ohmic contact electrode layer 50 and the substrate 10 are in ohmic contact. When the second ohmic contact electrode layer 50 and the substrate side electrode layer 52 are directly laminated, the second ohmic contact electrode layer 50 and the substrate side electrode layer 52 have poor adhesion and are easily peeled off. A second contact mediating layer 51 is interposed between the electrode layer 50 and the substrate-side electrode layer 52 to improve the adhesion of the second electrode portion 3B.

  FIG. 3 is a cross-sectional view schematically showing a state when the semiconductor laser element 1 is energized. Since the first contact layer 14A and the oxide film 30 are formed as described above, the semiconductor laser device 1 has a ridge waveguide structure and a current confinement structure. Therefore, the current flowing through the light emitting layer 2 passes from the first electrode portion 3A through the one surface 42 on one side in the third direction Z of the first contact layer 14A toward the second electrode portion 3B. The direction of the current flowing through the light emitting layer 2 is indicated by an arrow A in FIG. Further, the semiconductor laser device 1 includes the first cladding layer 11, the central portion of the active layer 12 in the second direction X, the central portion of the second cladding layer in the second direction X, and the second contact layer 14A. An optical waveguide is formed by the central portion in the direction X. A region where the optical waveguide is formed is shown surrounded by a broken line B in FIG.

  FIG. 4 is a cross-sectional view when the semiconductor laser device 1 of the present invention is connected to the connected body 55 by the solder 56. FIG. 5 is an enlarged cross-sectional view showing a connection portion between the semiconductor laser element 1 and the solder 56. The connected body 55 is a submount made of, for example, silicon (Si) for mounting the semiconductor laser element 1. The first electrode portion 3A of the semiconductor laser element 1 is connected to the connected body 55 by a solder 56 made of, for example, gold (Au) and tin (Sn). The solder 56 is also filled in a groove formed on one surface of the first electrode portion 3A on one side in the third direction Z. The material forming the first electrode portion 3A and the solder 56 are alloyed, and the reaction layer 57 is formed on the first electrode portion 3A. A reaction in which the solder 56 and the first electrode portion 3 </ b> A are alloyed first occurs at a portion where the bonding metal layer 36 and the solder 56 are in contact with each other. This alloying reaction proceeds from the portion where the bonding metal layer 36 and the solder 56 are in contact toward the light emitting layer 2, but the barrier metal layer 35 is formed of a material that is difficult to alloy with the solder 56. Further, since the layer thickness is selected as the fifth thickness T5, the reaction of alloying with the solder 56 stops at the barrier metal layer 35 and does not react any more.

  If the thickness of the barrier metal layer 35 is less than 50 nm, the alloying reaction with the solder 56 cannot be stopped by the barrier metal layer 35, and an alloy with solder is formed on the thick film electrode layer 34. It cannot serve as the barrier metal layer 35. Further, when the thickness of the barrier metal layer 35 is 1000 nm or more, the electric resistance of the barrier metal layer 35 is increased. If the electrical resistance of the first electrode portion 3A increases, the power consumed by the first electrode portion 3A out of the power supplied to the semiconductor laser element 1 increases, so that the function as an electrode is reduced.

  As a comparative example with respect to the present embodiment, a case where the sixth thickness T6 of the bonding metal layer 36 is larger than the thickness of the present embodiment and is selected to be 300 nm to 500 nm will be described. FIG. 6 is an enlarged cross-sectional view showing a connection portion between the semiconductor laser element and the solder 56 when the sixth thickness T6 of the bonding metal layer 36 is selected to be 300 nm to 500 nm.

  Since the bonding metal layer 36 is thicker than the semiconductor laser device 1 of the present embodiment, the entire bonding metal layer 36 is not uniformly alloyed with the solder 56. The bonding metal layer 36 includes a non-reactive layer 58 made of Au that is not alloyed with the solder 56 and a reactive layer 57. The reaction layer 57 has a hardness higher than that of the non-reaction layer 58, and a stress applied to the thick film electrode layer 34 is also large. Therefore, the stress applied to the thick film electrode layer 34 by the portion where the reaction layer 57 is formed across both ends in the third direction Z of the bonding metal layer is large. In comparison, the stress applied to the thick film electrode layer 34 by the portion where the reaction layer 57 and the non-reaction layer 58 are mixed over both ends in the third direction Z of the bonding metal layer is small. Therefore, the stress applied to the thick film electrode layer 34 varies. As a result, the strain stress of the thick film electrode layer 34 varies.

  As a comparative example with respect to the present embodiment, a case where the sixth thickness T6 of the bonding metal layer 36 is larger than the above-described thickness and is selected to be 500 nm or more will be described. FIG. 7 is an enlarged cross-sectional view showing a connection portion between the semiconductor laser element and the solder 56 when the sixth thickness T6 of the bonding metal layer 36 is selected to be 500 nm or more.

  When the sixth thickness T6 of the bonding metal layer 36 is large and selected to be 500 nm or more, the alloying reaction between the material forming the bonding metal layer 36 and the solder 56 does not proceed to the barrier metal layer 35. In this case, there arises a problem that variations in stress strain occur due to variations in alloying. Further, the barrier metal layer 35 does not play a role of stopping the alloying reaction, and the thickness of the reaction layer 57 in the third direction Z is increased. Since the hardness of the reaction layer 57 is greater than that of the bonding metal layer 36, the stress applied to the light emitting layer 2 by the bonding metal layer 36 increases as the thickness of the reaction layer 57 in the third direction Z increases. When the stress applied to the light emitting layer 2 is increased, the characteristics of the semiconductor laser device such as the slope efficiency, the light emitting efficiency, the lifetime, and the threshold current are deteriorated. Further, the thermal conductivity of the reaction layer 57 is smaller than the thermal conductivity of the non-reactive layer 58, and if the thickness of the reaction layer 57 in the third direction Z is increased, the heat dissipation effect of the first electrode portion 3A is reduced. Therefore, the characteristics of the semiconductor laser element are deteriorated.

  In addition, when the sixth thickness T6 of the bonding metal layer is smaller than the thickness of the embodiment of the present invention and less than 50 nm, the thickness of the reaction layer 57 is reduced. For this reason, the adhesion between the solder 56 and the first electrode portion 3 </ b> A is deteriorated, and the semiconductor laser element may be peeled off from the connected body 55.

  As shown in FIG. 5, in the semiconductor laser device 1 of the present embodiment, since the thickness of the bonding metal layer 36 is selected as T6, the bonding metal layer 36 is uniformly alloyed with the solder 56, and the bonding metal layer 36 is obtained. The whole becomes the reaction layer 57. The reaction layer 57 formed by alloying with the solder 56 applies stress to the thick film electrode layer 34, but the entire bonding metal layer 36 becomes the reaction layer 57, so the stress applied to the thick film electrode layer 34 varies. Absent. Therefore, the above-described problems are less likely to occur, and variations in the strain stress of the thick film electrode layer 34 are less likely to occur.

  Further, the thickness of the thick film electrode layer 34 of the semiconductor laser device 1 of the present embodiment is as thick as the fourth thickness T4, and the heat generated in the light emitting layer 2 when the semiconductor laser device is energized is reduced. The semiconductor laser device 1 can be efficiently dissipated by the one electrode portion 3A and has good characteristics.

  In addition, the shortest distance between the active layer 12 and the thick film electrode layer 34 of the semiconductor laser device 1 of the present embodiment is as short as 0.05 μm or more and 3 μm or less, and therefore occurs when the semiconductor laser device is energized. The semiconductor laser device 1 having good characteristics can be efficiently dissipated by the first electrode portion 3A.

  Further, since the thick film electrode layer 34 is separated from the bonding metal layer 36 by the barrier metal layer 35, a portion where the thick film electrode layer 34 and the bonding metal layer 36 are in contact does not occur. Therefore, the one surface 27 in the first direction Y of the bonding metal layer 36 and the solder 56 are in contact with each other, and an alloying reaction between the material forming the bonding metal layer 36 and the solder 56 causes the bonding metal layer 36 and the solder 56 to react. Even in the case of proceeding to the barrier metal layer 35 in the first direction Y from the contact surface, there is no portion where the thick film electrode layer 34 and the bonding metal layer 36 are in contact, so the material for forming the thick film electrode layer 34 and solder 56 is not alloyed. Therefore, variations in strain stress of the thick film electrode layer 34 are less likely to occur.

  The semiconductor laser device 1 according to the embodiment of the present invention forms a ridge waveguide. As described above, when the surface where the first electrode portion 3A and the light emitting layer 2 are in contact with each other is not a flat surface, that is, when the first electrode portion 3A and the light emitting layer 2 are in contact with each other with a curved surface, the variation in the strain stress of the thick film electrode layer 34 is. Therefore, the stress applied to the light emitting layer 2 may be locally concentrated. For example, stress may be concentrated on one surface 28 in contact with the oxide film 30 and the first ohmic contact layer 31 of the first contact layer 14A. In this case, the characteristics of the semiconductor laser element 1 are deteriorated. However, in the embodiment of the present invention, since the variation of the strain stress of the thick film electrode layer 34 is reduced, the locally concentrated stress is large. In addition, the semiconductor laser element 1 with good characteristics is obtained.

  In the semiconductor laser device 1 according to the embodiment of the present invention, the semiconductor laser device that forms the ridge-type waveguide has been described. However, the semiconductor laser device that forms the rib waveguide also has a thick film electrode layer. Dispersion of strain stress can be reduced, and a semiconductor laser element with good characteristics can be obtained. In the semiconductor laser device 1 according to the embodiment of the present invention, the case where the first electrode portion 3A and the light emitting layer 2 are in contact with each other on a curved surface has been described. However, the case where the first electrode portion and the light emitting layer are in contact with each other on a plane is described. Even if it is a semiconductor laser element, the dispersion | variation in the distortion stress of a thick film electrode layer can be reduced, and it becomes a semiconductor laser element with a sufficient characteristic.

  Next, a method for manufacturing the semiconductor laser element 1 will be described. FIG. 8 is a flowchart showing the manufacturing procedure of the semiconductor laser device 1.

  The semiconductor laser element 1 is manufactured by dividing the semiconductor laser element precursor 101 by a cleavage process. The semiconductor laser element precursor 101 includes a substrate precursor 110 to be the substrate 10 after the cleavage step, a light emitting layer precursor 102 to be the light emitting layer 2 after the cleavage step, and a second electrode portion 3B to be the second electrode portion 3B after the cleavage step. A two-electrode part precursor 103B and a first electrode part precursor 103A to be the first electrode part 3A after the cleavage step are configured.

  The names of the layers constituting the semiconductor laser element precursor 101 are defined below. After cleaving the semiconductor laser element precursor 101, the layer to be the first cladding layer 11 is the first cladding layer precursor 111, the layer to be the active layer 12 is the active layer precursor 112, and the second cladding layer 13 is. The layer to be the second contact layer precursor 114B, the layer to be the second contact layer 14B, the second contact layer precursor 114B, the layer to be the second contact layer 14B, the third contact The layer to be the layer 14C is the third contact layer precursor 114C, the layer to be the oxide film 30 is the oxide film precursor 130, and the layer to be the first ohmic contact electrode layer 31 is the first ohmic contact electrode layer precursor 131. The layer to be the first contact mediating layer 32 is the first contact mediating layer precursor 132, the layer to be the thin film electrode layer 33 is the thin film electrode layer precursor 133, and the thick film A layer to be the polar layer 34 is a thick film electrode layer precursor 134, a layer to be the barrier metal layer 35 is a barrier metal layer precursor 135, a layer to be the bonding metal layer 36 is a bonding metal layer precursor 136, and a second layer. The layer to be the ohmic contact electrode layer 50 is the second ohmic contact electrode layer precursor 150, the layer to be the second contact mediating layer 51 is the second contact mediating layer precursor 151, and the layer to be the substrate-side electrode layer 52 Is defined as a substrate-side electrode layer precursor 152.

  FIG. 9 is a partial cross-sectional view of the substrate precursor 110, the light emitting layer precursor 102, and the second electrode portion precursor 103B after step S2. FIG. 10 is a partial cross-sectional view of the substrate precursor 110, the light emitting layer precursor 102, the second electrode portion precursor 103B, and the first electrode portion precursor 103A being formed after step S6. . FIG. 11 is a partial cross-sectional view of the substrate precursor 110, the light emitting layer precursor 102, the second electrode portion precursor 103B, and the first electrode portion precursor 103A after step S9. FIG. 12 is a perspective view schematically showing a part of the substrate precursor 110, the light emitting layer precursor 102, the second electrode portion precursor 103B, and the first electrode portion precursor 103A after step S9. is there.

  When the manufacture of the semiconductor laser device 1 is started, the process proceeds from step S0 to step S1, and in step S1, the light emitting layer precursor 102 is formed. One of the thickness directions of the substrate precursor 110 is defined so as to coincide with one of the third directions Z. The light emitting layer precursor 102 includes a first cladding layer precursor 111 made of n-type AlGaAs, an active layer precursor 112 made of AlGaAs, and a p-type AlGaAs on one surface 122 in the third direction Z of the substrate precursor 110. The second cladding layer precursor 113 and the contact layer precursor made of p-type GaAs are deposited in this order by the liquid layer epitaxial method. Next, the contact layer precursor is processed by a lithography process to form a first contact layer precursor 114A, a second contact layer precursor 114B, and a third contact layer precursor 114C.

  Next, the process proceeds to step S2, and in step S2, the second electrode part precursor 103B is formed. The second electrode portion precursor 103B is formed on the other surface 121 of the other side 121 in the third direction Z of the n-type GaAs substrate precursor 110. The second ohmic contact electrode layer precursor 150 made of, for example, AuGeNi, for example, the second contact made of Ti. The intermediate layer precursor 151 and the substrate-side electrode layer precursor 152 made of Au are stacked in this order by vacuum deposition. Next, in order to make ohmic contact between the substrate precursor 110 and the second ohmic contact electrode layer precursor 150, the substrate precursor 110 and the second ohmic contact electrode layer precursor 150 are heated at 400 to 500 ° C. for 10 minutes. And alloy processing.

Next, the process proceeds to step S3. In step S3, the oxide film precursor 130 of the first electrode portion precursor 103A is formed. An SiO ₂ film is formed on one surface 120 in the third direction Z of the light emitting layer precursor 102 by, for example, a chemical vapor deposition (abbreviated to CVD) method. Thereafter, the SiO ₂ film deposited on one surface 142 in the third direction Z of the first contact layer precursor 114A is removed by a lithography process to form the oxide film precursor 130.

  Next, the process proceeds to step S4, and in step S4, the first ohmic contact electrode layer precursor 131 is formed. The first ohmic contact electrode layer precursor 131 has a thickness on one surface 144 in the third direction Z of the oxide film precursor 130 and on one surface 142 in the third direction Z of the first contact layer precursor 114A. Tn AuZn is deposited by, for example, electron beam evaporation. Next, in order for the first contact layer precursor 114A and the first ohmic contact electrode layer precursor 131 to make ohmic contact, the first contact layer precursor 114A and the first ohmic contact electrode layer precursor 131A are heated at 400 to 500 ° C. for 10 minutes. The ohmic contact electrode layer precursor 131 is alloyed.

  Next, the process proceeds to step S5. In step S5, the first contact mediating layer precursor 132 is formed. The first contact medium layer precursor 132 is formed by depositing Ti having a thickness T2 on one surface 145 in the third direction Z of the first ohmic contact electrode layer precursor 131 by, for example, an electron beam evaporation method. .

  Next, the process proceeds to step S6. In step S6, a thin film electrode layer precursor 133 is formed. The thin film electrode layer precursor 133 is formed by depositing Au having a thickness of T3 on one surface 146 in the third direction Z of the first contact medium layer precursor 132 by, for example, an electron beam evaporation method.

  Next, the process proceeds to step S7, where the thick film electrode layer precursor 134 is formed. A photoresist film is applied on one surface 147 in the third direction Z of the thin-film electrode layer precursor 133. An unnecessary photoresist film is removed through an exposure process and a development process, and a photoresist layer is left only between a virtual plane to be cleaved and a plane separated from the virtual plane by a distance U1. The layer thickness of the photoresist layer in the third direction Z is selected to be thicker than the fourth thickness T4 of the thick film electrode layer. The thick film electrode layer precursor 134 is formed by depositing Au having a fourth thickness T4 on a portion of the one surface 147 in the third direction Z of the thin film electrode layer precursor 133 that is not in contact with the photoresist layer by a plating method. Formed. Since the layer thickness of the photoresist layer in the third direction Z is thicker than T4, the thick film electrode layer precursor 134 is not formed on the photoresist layer. Thereafter, the photoresist layer is removed by an etching process.

  Next, the process proceeds to step S8, and in step S8, the barrier metal layer precursor 135 is formed. The thick film electrode layer precursor 134 is not in contact with the thick film electrode layer precursor 134 on the one surface 148 in the third direction Z of the thick film electrode layer precursor 134 and on the one surface 147 in the third direction Z of the thin film electrode layer precursor 133. A photoresist layer is formed on the portion. An unnecessary photoresist layer is removed through an exposure process and a development process, and the photoresist layer is left only between a virtual plane to be cleaved and a plane separated from the virtual plane by a distance U2. The thickness of the photoresist layer in the third direction Z is selected to be thicker than the thickness of the fourth thickness T4 of the thick film electrode layer 34 plus the fifth thickness T5 of the barrier metal layer 35. Thereafter, the barrier metal layer precursor 135 is on one surface 148 in the third direction Z of the thick film electrode layer precursor 134 and on one surface 147 in the third direction Z of the thin film electrode layer precursor 133. For example, Ti having a fifth thickness T5 is deposited by plating on a portion not in contact with the thick film electrode layer precursor 134 and the photoresist layer. Since the layer thickness in the third direction Z of the photoresist layer is thicker than the value obtained by adding the fifth thickness T5 to the fourth thickness T4, the barrier metal layer precursor 135 is not formed on the photoresist layer. Thereafter, the photoresist layer is removed by an etching process.

  Next, the process proceeds to step S9, and in step S9, a bonding metal layer precursor 136 is formed. The bonding metal layer precursor 136 is a thick film electrode on one surface 149 in the third direction Z of the barrier metal layer precursor 135 and on one surface 146 in the third direction Z of the thin film electrode layer precursor 133. Au having a thickness of T6 is formed by plating on a portion not in contact with the layer precursor 134 and the barrier metal layer precursor 135.

  Next, the process proceeds to step S10. In step S10, the semiconductor laser element precursor 101 is cleaved. The semiconductor laser element precursor 101 is cleaved and cleaved to divide the semiconductor laser element precursor 101 into a plurality of semiconductor laser elements 1. A plane to be cleaved is indicated by a virtual line C in FIG.

Next, the process proceeds to step S11, where the manufacture of the semiconductor laser device 1 is completed.
When the thick film electrode layer precursor 134 and the barrier metal layer precursor 135 are formed on the surface to be cleaved of the semiconductor laser element precursor 101, the thick film electrode layer precursor 134 and the barrier metal layer precursor 135 are formed. Since it is difficult to divide compared with the light emitting layer precursor 102, it becomes difficult to divide the semiconductor laser device 101 in the cleavage step. For this reason, a division failure may occur in the semiconductor laser device 1 in the cleavage step. On the other hand, in the present embodiment, the thick film electrode layer precursor 134 and the barrier metal layer precursor 135 are not formed on the surface to be cleaved of the semiconductor laser element precursor 101. No division failure due to the layer precursor 134 and the barrier metal layer precursor 135 occurs. Therefore, the semiconductor laser element 1 with good characteristics can be manufactured. In addition, since the division defects generated in the semiconductor laser element 1 are reduced, the yield of the semiconductor laser element 1 is improved and the manufacturing cost can be reduced.

  The thick film electrode layer precursor 134 according to the embodiment of the present invention is formed by an electrolytic plating method. In the electroless plating method, the film formation rate is slow, and the film thickness and the variation are large. Therefore, the stress strain variation due to the film thickness variation is large. Therefore, the thick film electrode layer precursor 34 formed by the electrolytic plating method has less variation in strain stress than that formed by the electroless plating method.

  After forming the thick film electrode layer precursor 134 with little variation in strain stress by plating in step S7, if the temperature of the thick film electrode layer precursor 134 becomes 350 ° C. or higher in the steps S8 to S10, thermal stress As a result, the strain stress of the thick film electrode layer precursor 134 varies. In the process of forming the second electrode part precursor 103B in step S2, in order to take ohmic contact between the light emitting layer precursor 102 and the second electrode part precursor 103B, an alloy process at 400 to 500 ° C. is performed. In the present embodiment, after forming the second electrode part precursor 103B in step S2, the thick film electrode layer precursor 134 is formed in step S7. Further, the temperature of the thick film electrode layer precursor 134 in the process of Step S8 and Step S9 in which the barrier metal layer precursor 135 and the bonding metal layer precursor 136 are laminated is 50 ° C. or higher and lower than 350 ° C. Therefore, in the step after the thick film electrode layer precursor 134 is formed, the temperature of the thick film electrode layer precursor 134 does not become 350 ° C. or higher, so that the variation in strain stress of the thick film electrode layer precursor 134 is reduced. Can do. Further, in the process after the thick film electrode layer precursor 134 is formed, if the temperature of the thick film electrode layer precursor 134 becomes less than 50 ° C. and the amount of change in the temperature of the thick film electrode layer precursor 134 increases, Variation in strain stress of the thick film electrode layer precursor 134 increases, but the temperature of the thick film electrode layer precursor 134 is maintained in a temperature range of 50 ° C. or higher and lower than 350 ° C. The variation in strain stress of the thick film electrode layer precursor 134 that occurs after forming the film can be reduced.

  When there is variation in the strain stress of the thick film electrode layer, the radiation angle of the laser beam may be disturbed. For example, when the angle is changed from a direction parallel to the surface of the active layer, there may be a problem that the light intensity does not change smoothly. In addition, a transition may occur in the active layer due to the stress that the thick film electrode layer exerts on the active layer of the semiconductor laser element. In a place where there is a transition, even if the semiconductor laser element is energized, non-radiative recombination is caused, a large amount of heat is generated, and no light is emitted. In addition, the transition spreads in the active layer centering on the transition generated in the active layer due to the heat generated by energizing the semiconductor laser element. Therefore, when the semiconductor laser element is continuously energized, the transition grows around the transition generated in the active layer, and finally the semiconductor laser element does not oscillate. Therefore, when a transition occurs in the active layer due to the stress applied by the thick film electrode layer, the characteristics of the semiconductor laser device such as a decrease in slope efficiency, a decrease in light emission efficiency, an increase in threshold current, and a decrease in lifetime are observed. Getting worse. In particular, if there is variation in the strain stress of the thick film electrode layer, stress may be applied to a local portion of the active layer, and the transition tends to occur in that portion. As a result, the characteristics of the semiconductor laser element deteriorate.

  Since the semiconductor laser device 1 according to the present embodiment reduces variations in the strain stress of the thick film electrode layer 34, the stress applied to the active layer 12 by the thick film electrode layer 34 is uniform, and the thick film electrode layer The influence of 34 on the active layer 12 is reduced. As a result, the semiconductor laser device 1 with good characteristics is obtained.

  FIG. 13 is a graph showing the light intensity distribution in the far field of the emitted light of the semiconductor laser element having the barrier metal layer in the electrode part, and the output at each voltage when the voltage applied to the semiconductor laser element is changed. Represents the light intensity distribution in the far field of incident light. The horizontal axis in FIG. 13 represents the emission angle. The emission angle is defined as the angle between the optical axis and the straight line connecting the position where the laser beam is emitted and the measurement position on the virtual plane that includes the optical axis and is perpendicular to the thickness direction of the active layer. The vertical axis in FIG. 13 represents the light intensity. As shown in FIG. 13, the light intensity of the semiconductor laser element having the barrier metal layer in the electrode portion monotonously decreases as the absolute value of the emission angle increases.

  As a comparative example of a semiconductor laser element having a barrier metal layer in the electrode part, a semiconductor laser having no barrier metal layer in the electrode part, excluding only the barrier metal layer from the configuration of the semiconductor laser element having the barrier metal layer in the electrode part FIG. 14 shows the light intensity distribution in the far field of the light emitted from the element. FIG. 14 is a graph showing the light intensity distribution in the far field of the emitted light of the semiconductor laser element that does not have a barrier metal layer in the electrode part, and shows the change in voltage applied to the semiconductor laser element at each voltage. It represents the light intensity distribution in the far field of the emitted light. The horizontal axis in FIG. 14 represents the laser beam emission angle. The vertical axis in FIG. 14 represents the light intensity. As shown in FIG. 14, the light intensity of the semiconductor laser element having no barrier metal layer in the electrode portion does not monotonously decrease as the absolute value of the radiation angle increases, but the absolute value of the radiation angle. Other than the peak around 0 °, the absolute value of the radiation angle also has a peak at the tail portion away from 0 °.

  As described above, by forming the barrier metal layer in the electrode portion, it is possible to obtain a semiconductor laser device in which the light intensity in the far field monotonously decreases as the absolute value of the emission angle increases. Therefore, it is possible to obtain a semiconductor laser element with good characteristics that can use a wide range of emission angles of laser light.

It is sectional drawing of the semiconductor laser element which is embodiment of this invention. 1 is a perspective view of a semiconductor laser device according to an embodiment of the present invention. It is sectional drawing of the semiconductor laser element which is embodiment of this invention, and shows typically the direction through which an optical waveguide and an electric current flow. It is sectional drawing of the semiconductor laser element which is embodiment of this invention, and a to-be-connected body. It is an expanded sectional view of a part of connection part of the 1st electrode part and to-be-connected body of the semiconductor laser element which is embodiment of this invention. FIG. 4 is an enlarged cross-sectional view of a part of the connection portion between the first electrode portion and the connected body of the semiconductor laser device having a bonding metal layer thicker than the thickness of the bonding metal layer of the semiconductor laser device according to the embodiment of the present invention. is there. FIG. 4 is an enlarged cross-sectional view of a part of the connection portion between the first electrode portion and the connected body of the semiconductor laser device having a bonding metal layer thicker than the thickness of the bonding metal layer of the semiconductor laser device according to the embodiment of the present invention. is there. It is a flowchart which shows the manufacture procedure of the semiconductor laser element which is embodiment of this invention. It is sectional drawing of the semiconductor laser element which is embodiment of this invention in the middle of manufacture after completion | finish of step S2. It is sectional drawing of the semiconductor laser element which is embodiment of this invention in the middle of manufacture after completion | finish of step S6. It is sectional drawing of the semiconductor laser element which is embodiment of this invention in the middle of manufacture after completion | finish of step S9. It is a perspective view of the semiconductor laser element which is embodiment of this invention in the middle of manufacture after completion | finish of step S9. It is a graph showing the light intensity distribution in the far field of the emitted light of the semiconductor laser element which has a barrier metal layer. It is a graph showing the light intensity distribution in the far field of the emitted light of the semiconductor laser element which does not have a barrier metal layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser element 2 Light emitting layer 3A 1st electrode part 3B 2nd electrode part 10 Substrate 11 1st cladding layer 12 Active layer 13 2nd cladding layer 14A 1st contact layer 14B 2nd contact layer 14C 3rd contact layer 30 Oxide film 31 first ohmic contact electrode layer 32 first contact mediating layer 33 thin film electrode layer 34 thick film electrode layer 35 barrier metal layer 36 bonding metal layer 50 second ohmic contact electrode layer 51 second contact mediating layer 52 substrate side electrode layer 55 covered Connection 56 Solder

Claims (10)

A semiconductor substrate, a light emitting layer formed by laminating a semiconductor layer on one surface of the semiconductor substrate, and a surface of the light emitting layer on one side in the stacking direction of the semiconductor layer are provided on the surface of the connected body by soldering. A semiconductor laser element including an electrode part to be connected,
The electrode part
An electrode layer provided near the light emitting layer;
A barrier metal layer that is laminated on the surface of the electrode layer opposite to the light emitting layer and prevents a compound of the material forming the electrode layer and the solder from being formed by the solder;
The barrier metal layer is laminated on the surface opposite to the electrode layer, and has a bonding metal layer connected to the connected body,
The light emitting layer has an active layer,
The shortest distance between the electrode layer and the active layer is selected from 0.05 μm to 3 μm,
A thickness of the electrode layer is selected from 0.5 μm to 5 μm.   2. The semiconductor laser device according to claim 1, wherein one surface of the light emitting layer in contact with the electrode portion is a curved surface.   The semiconductor laser element according to claim 1, wherein the electrode layer is formed by a plating method.   4. The semiconductor laser device according to claim 1, wherein a thickness of the barrier metal layer is selected to be not less than 50 nm and less than 1000 nm.   5. The semiconductor laser device according to claim 1, wherein the barrier metal layer is formed of at least one of molybdenum, titanium, and titanium nitride.   6. The semiconductor laser device according to claim 1, wherein the barrier metal layer covers a remaining surface except one surface facing the light emitting layer of the electrode layer. 7.   The said electrode layer is formed in the part except the peripheral part of the light emitting layer seeing from the lamination direction one side of the semiconductor layer of a light emitting layer, The any one of Claims 1-6 characterized by the above-mentioned. Semiconductor laser element.   The said barrier metal layer is formed in the part except the peripheral part of the light emitting layer seeing from the lamination direction one side of the semiconductor layer of a light emitting layer, The any one of Claims 1-7 characterized by the above-mentioned. Semiconductor laser device. A method for manufacturing a semiconductor laser device, for manufacturing the semiconductor laser device according to claim 1,
The semiconductor laser element includes a second electrode portion provided on the other surface of the semiconductor substrate,
After forming the said light emitting layer, a 2nd electrode part is formed, and the said electrode part is formed on one surface of a light emitting layer after that, The manufacturing method of the semiconductor laser element characterized by the above-mentioned.   9. The method of manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device is manufactured in a temperature range of 50 [deg.] C. or higher and lower than 350 [deg.] C. in the step after forming the electrode layer.

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