JP2006344743A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device reducing a stress applied to an adhesive layer between a semiconductor laser element and a supporting member or between the supporting member and a heat-dissipating member, and being capable of improving a reliability. <P>SOLUTION: A sub-mount 30 is disposed between an LD bar 10 and a heat sink 20, and each of the LD bar, heat sink and sub-mount is joined by a first adhesive layer 40 and a second adhesive layer 50 composed of a solder or a gold (Au)-tin (Sn) solder. A first layer 31 in the sub-mount 30 has approximately the same coefficient of thermal expansion as the LD bar 10 in copper tungsten (CuW) or the like, and a second layer 32 has approximately the same coefficient of thermal expansion as the heat sink 20 in copper (Cu) or the like. The stress applied to the first adhesive layer 40 and the second adhesive layer 50 is reduced, and the reliability is improved. The first layer 31 and the second layer 32 are formed in an integral structure by a mutual joining by a soldering or a diffusion junction, and the stress by the difference of the coefficients of thermal expansion is absorbed surely on a firm junction interface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device in which a support member is disposed between a semiconductor laser element and a heat radiating member, and each is joined by an adhesive layer, and particularly suitable for an infrared laser using a GaAs substrate. About.

  In a high-power semiconductor laser of several W to several tens W class, a semiconductor laser element called a laser diode bar (LD bar) in which light emitting points are arranged two-dimensionally is frequently used for high output and improved reliability. The Large heat is generated from the LD bar, and the amount of heat generated increases in proportion to the output. Therefore, the heat sink (heat radiating member) on which the LD bar is arranged is mainly high in heat conductivity and easy to process. Copper (Cu) is used.

The thermal expansion coefficient of copper (Cu) is about 17 × 10 ⁻⁶ [1 / K], whereas the thermal expansion coefficient of a GaAs substrate generally used in a high-power semiconductor laser is 5.9 ×. There is a large difference of 10 ⁻⁶ [1 / K]. Therefore, for example, when an LD bar formed on a GaAs substrate is soldered to a heat sink made of copper (Cu) and cooled to room temperature, stress is generated in the LD bar. It is known that energization of the LD bar in a stressed state promotes the growth of crystal defects and adversely affects the reliability of the laser.

  Conventionally, in order to avoid this problem, for example, a submount (support member) using copper tungsten (CuW) or the like as a material having a coefficient of thermal expansion that is relatively close to that of the constituent material of the LD bar is interposed between the LD bar and the heat sink. It was arranged to be.

Further, it has been proposed to dispose a plurality of submounts between the LD bar and the heat sink. For example, in Patent Document 1, an SiC submount and a diamond submount are sequentially stacked on a heat sink, and a laser chip is disposed thereon. For example, in Patent Document 2, the submount has a three-layer structure of an upper layer, an intermediate layer, and a lower layer, the upper layer and the lower layer are made of diamond, and the intermediate layer is made of copper.
JP-A-11-307875 JP 2001-291925 A

  However, conventionally, an adhesive layer made of a soft solder such as indium (In) solder is provided between the LD bar and the submount and between the submount and the heat sink, and this adhesive layer reduces the stress generated during joining. I was trying to absorb and relax. Therefore, there is a problem in that stress is applied to the solder constituting the adhesive layer and stress migration occurs, or the stress applied to the solder fluctuates due to continuous output on / off, and the solder is plastically deformed and deteriorated.

  The present invention has been made in view of such problems, and its purpose is to reduce the stress applied to the adhesive layer between the semiconductor laser element and the support member, or between the support member and the heat dissipation member, thereby improving reliability. An object of the present invention is to provide a semiconductor laser device that can be enhanced.

The semiconductor laser device according to the present invention has the following requirements (A) to (E) to improve reliability.
(A) a semiconductor laser element (B) a heat radiating member having a larger thermal expansion coefficient than that of the semiconductor laser element (C) a first layer having a thermal expansion coefficient substantially equal to that of the semiconductor laser element and disposed on the surface on the semiconductor laser element side; And having a thermal expansion coefficient substantially equal to that of the heat dissipating member and a laminated structure of a plurality of layers including a second layer disposed on the back surface on the heat dissipating member side, and the plurality of layers are bonded to each other by brazing or diffusion bonding A support member (D) joined to form an integral structure, a first adhesive layer that joins the semiconductor laser element and the support member, and a second adhesive layer that joins the heat dissipation member and the support member.

Here, “the first layer has a thermal expansion coefficient substantially equal to that of the semiconductor laser element” means that the first layer and the semiconductor laser element have the same thermal expansion coefficient, or the first layer and the semiconductor laser element have thermal expansion coefficients. The coefficient difference is smaller than the thermal expansion coefficient difference between the first layer and the heat dissipation member. Similarly, the second layer “has substantially the same thermal expansion coefficient as that of the heat radiating member” means that the second layer and the heat radiating member have the same thermal expansion coefficient or a difference in thermal expansion coefficient between the second layer and the heat radiating member. Is smaller than the difference in thermal expansion coefficient between the second layer and the semiconductor laser element. The difference in thermal expansion coefficient between the first layer and the semiconductor laser element or the difference in thermal expansion coefficient between the second layer and the heat radiating member is preferably 4 × 10 ⁻⁶ [1 / K] or less, and is 1 to 2 ×. 10 ⁻⁶ [1 / K] or less is more preferable, and 0.5 × 10 ⁻⁶ [1 / K] or less is more preferable.

  In this semiconductor laser device, since the thermal expansion coefficients of the semiconductor laser element and the first layer of the support member are substantially equal, the thermal expansion coefficients of the heat dissipation member and the second layer of the support member are substantially equal. Stress applied to the adhesive layer and the second adhesive layer is reduced. Thereby, it is suppressed that the solder etc. which comprise the 1st adhesion layer and the 2nd adhesion layer will break by stress migration or quality change. The difference in thermal expansion coefficient between the semiconductor laser element and the heat radiating member is absorbed as stress at the bonding interface of the plurality of layers of the support member, but the bonding interface is generally brazed or more reliable than soldering. Since the bonding is firmly performed by diffusion bonding, an event in which a plurality of layers of the support member are separated by stress is suppressed.

  According to the semiconductor laser device of the present invention, the thermal expansion coefficient of the first layer of the support member is made substantially equal to that of the semiconductor laser element, while the thermal expansion coefficient of the second layer is made substantially equal to that of the heat radiating member. And the stress concerning a 2nd contact bonding layer can be reduced and reliability can be improved. In addition, since the plurality of layers are joined to each other by brazing or diffusion bonding to form an integral structure, the difference in thermal expansion coefficient between the semiconductor laser element and the heat dissipation member can be reliably confirmed as stress at the bonding interface of the plurality of layers. Can be absorbed, and the reliability can be further improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows the configuration of the semiconductor laser device according to the first embodiment of the present invention. This semiconductor laser device is used as, for example, a YAG excitation light source, and has a configuration in which a submount 30 is disposed between the LD bar 10 and the heat sink 20. The LD bar 10 is joined to the submount 30 by a first adhesive layer 40 made of, for example, brazing or gold (Au) -tin (Sn) solder, and the heat sink 20 is made of, for example, brazing or gold (Au) -tin (Sn) solder. The second adhesive layer 50 is joined to the submount 30.

  FIG. 2 is an enlarged view of a part of the LD bar 10 shown in FIG. The LD bar 10 is an infrared laser formed on a substrate 11 made of gallium arsenide (GaAs). The LD bar 10 is formed by arranging a plurality of laser diode (LD) chips 12 in parallel. The dimensions thereof are, for example, a width of about 10 mm, a resonator length of 200 μm to 1.5 mm, specifically about 700 μm, The thickness is about 100 μm. Here, the width is the dimension in the arrangement direction of the laser diode chips 12, the resonator length is the dimension in the emission direction of the light LB from the LD bar 10, that is, the dimension in the resonator direction, and the thickness is the laser. It is a dimension in a direction orthogonal to both the arrangement direction of the diode chips 12 and the resonator direction.

  The LD bar 10 has a semiconductor layer 13 including an active layer made of an AlGaAs compound semiconductor on a substrate 11. The AlGaAs-based compound semiconductor here is a ternary element including at least one of aluminum (Al) and gallium (Ga) among 3B group elements in the short period type periodic table and arsenic (As) among 5B group elements. It is a system semiconductor. These contain an n-type impurity such as silicon (Si) or selenium (Se), or a p-type impurity such as magnesium (Mg), zinc (Zn), or carbon (C) as necessary.

  On the semiconductor layer 13, for example, a p-side electrode 14 is formed corresponding to each laser diode chip 12. The p-side electrode 14 has a configuration in which, for example, a titanium (Ti) layer, a platinum (Pt) layer, and a gold (Au) layer are sequentially stacked from the semiconductor layer 13 side. Further, on the back surface of the substrate 11, for example, n-side electrodes 15 are provided corresponding to the respective laser diode chips 12. The n-side electrode 15 has a configuration in which, for example, a gold (Au) layer, an alloy layer of gold (Au) and germanium (Ge), and a gold (Au) layer are sequentially stacked from the substrate 11 side. The LD bar 10 is usually bonded so that the p-side electrode 14 faces the submount 30, but may be bonded so that the n-side electrode 15 faces the submount 30. .

  The heat sink 20 shown in FIG. 1 has a function as a heat radiating member that releases a large amount of intense heat generated from the LD bar 10 and maintains the LD bar 10 at an appropriate temperature. The heat sink 20 is made of, for example, copper (Cu) having high thermal conductivity, and has a thermal expansion coefficient larger than that of the LD bar 10. The heat sink 20 also has a function as an electrode member that conducts current from a power source (not shown) to the LD bar 10.

  The submount 30 shown in FIG. 1 has a laminated structure of a first layer 31 disposed on the surface on the LD bar 10 side and a second layer 32 disposed on the back surface on the heat sink 20 side. As shown in FIG. 3, the first layer 31 has a thermal expansion coefficient substantially equal to that of the LD bar 10, and the second layer 32 has a thermal expansion coefficient substantially equal to that of the heat sink 20. Thereby, in this semiconductor laser device, the stress applied to the first adhesive layer 40 and the second adhesive layer 50 can be reduced and the reliability can be improved.

  The first layer 31 and the second layer 32 are joined together by brazing or diffusion joining to form an integral structure. These joining methods are generally more reliable than soldering, and a strong joining interface can be obtained. Therefore, in this semiconductor laser device, the stress due to the difference in thermal expansion coefficient can be reliably absorbed at the bonding interface between the first layer 31 and the second layer 32, and the reliability can be further improved. Yes.

  The first layer 31 is made of, for example, a material containing metal, a material containing diamond, or ceramic. Among them, the material containing diamond has high thermal conductivity, and heat diffusion is performed not only in the vertical direction (stacking direction of the first layer 31 and the second layer 32) but also in the horizontal direction (in-plane direction of the first layer 31). This is preferable because it can promote and spread heat over a wider range to increase exhaust heat efficiency.

As a material containing a metal, for example, an alloy (kovar) containing iron (Fe), nickel (Ni) and cobalt (Co) (thermal expansion coefficient 5.3 × 10 ⁻⁶ [1 / K]), or copper tungsten (CuW) (coefficient of thermal expansion 6.5 × 10 ⁻⁶ [1 / K]).

Examples of the material containing diamond include diamond (thermal expansion coefficient 2.3 × 10 ⁻⁶ [1 / K]), or a composite material of metal such as copper (Cu) and diamond (composite diamond) (thermal expansion coefficient (example ) 4-6 × 10 ⁻⁶ [1 / K]). The thermal expansion coefficient of the composite material of metal and diamond varies depending on the material and composition. The composite material of metal and diamond may not be able to form sharp edges at the corners of the end face. However, by adopting a laminated structure with the second layer 32, it is easy to form sharp edges and the heat exhaust efficiency is also improved. Can be increased.

Examples of the ceramic include aluminum nitride (AlN) (thermal expansion coefficient 4.5 × 10 ⁻⁶ [1 / K]) or silicon carbide (SiC) (thermal expansion coefficient 3.8 × 10 ⁻⁶ [1 / K]. ). When the first layer 31 is made of ceramic, a metal coating layer (not shown) made of gold (Au) plating or the like is formed on the surface of the first layer 31, and electrical connection with the LD bar 10 can be established. It is desirable to do so.

The second layer 32 is made of copper (Cu) (thermal expansion coefficient: 17 × 10 ⁻⁶ [1 / K]), for example, like the heat sink 20. Thereby, even if the 2nd contact bonding layer 50 is comprised with hard solders, such as brazing | wax or gold | metal | money (Au) -tin (Sn) solder, the stress concerning the 2nd contact bonding layer 50 can be reduced. In addition, the constituent material of the second layer 32 may be another metal having a thermal expansion coefficient close to that of copper (Cu), for example, stainless steel (thermal expansion coefficient (example) 17 to 18 × 10 ⁻⁶ [1 / K]). Good.

  The total thickness of the first layer 31 and the second layer 32 is preferably, for example, 0.15 mm or more and 0.3 mm or less. In addition, the thickness of each of the first layer 31 and the second layer 32 is appropriately set so that the warpage after joining the first layer 31 and the second layer 32 is reduced in consideration of the thermal expansion coefficient and rigidity of each. It is desirable to define.

  This semiconductor laser device can be manufactured, for example, as follows.

  First, for example, on the front side of the substrate 11 made of the above-described material, for example, by MOCVD (Metal Organic Chemical Vapor Deposition) method or MBE (Molecular Beam Epitaxy) method, A semiconductor layer 13 is formed. Next, the p-side electrode 14 and the n-side electrode 15 are formed, and the substrate 11 is adjusted to a predetermined size. Thereby, the LD bar 10 shown in FIG. 2 is formed.

  Next, the first layer 31 and the second layer 32 made of the above-described thickness and material are prepared, and these are joined together by brazing or diffusion bonding to form an integrated structure, thereby forming the submount 30. A first adhesive layer 40 made of, for example, the above-described material is provided on the surface of the submount 30 on the LD bar 10 side.

  Subsequently, the LD bar 10 and the submount 30 are heated and pressure-bonded at the same time, thereby bonding the first adhesive layer 40 therebetween. The bonding temperature is, for example, about 300 ° C. or more when the first adhesive layer 40 is brazed, and about 280 ° C. to 350 ° C. for a gold (Au) -tin (Sn) alloy, for example.

  After that, the heat sink 20 made of the above-described material is prepared, and the second adhesive layer 50 made of the above-described material is provided in the region where the submount 30 of the heat sink 20 is disposed. Subsequently, the second adhesive layer 50 provided on the heat sink 20 and the back surface of the submount 30 are made to face each other, alignment is performed with high accuracy, and the submount 30 is placed on the heat sink 20. After that, the back surface of the submount 30 is bonded to the heat sink 20 with the second adhesive layer 50 in between by heating and pressing. The bonding temperature is the same as that of the first adhesive layer 40. Thus, the semiconductor laser device shown in FIG. 1 is completed.

  In this semiconductor laser device, when a predetermined voltage is applied between the n-side electrode 15 and the p-side electrode 14 of each laser diode chip 12, current is injected into the active layer of the semiconductor layer 13, and electron-hole Luminescence occurs due to recombination. Here, since the thermal expansion coefficients of the LD bar 10 and the first layer 31 are substantially equal, and the thermal expansion coefficients of the heat sink 20 and the second layer 32 are substantially equal, the first adhesive layer 40 and the second adhesion layer 40 are the same. The stress on the layer 50 is reduced. Thereby, it is suppressed that the solder etc. which comprise the 1st contact bonding layer 40 and the 2nd contact bonding layer 50 will break by stress migration or quality change.

  Further, the difference in thermal expansion coefficient between the LD bar 10 and the heat sink 20 is absorbed as stress at the bonding interface between the first layer 31 and the second layer 32. Since the bonding interface is generally firmly bonded by brazing or diffusion bonding, which is generally more reliable than soldering, an event in which the first layer 31 and the second layer 32 are separated by stress is suppressed.

  Thus, in the semiconductor laser device of the present embodiment, the first layer 31 of the submount 30 has a thermal expansion coefficient substantially equal to that of the LD bar 10, while the second layer 32 has a thermal expansion coefficient substantially equal to that of the heat sink 20. Since it did in this way, the stress concerning the 1st contact bonding layer 40 and the 2nd contact bonding layer 50 can be reduced, and reliability can be improved. Further, the stress on the LD bar 10 can be relaxed, and a more reliable semiconductor laser device can be realized.

  Furthermore, since the first layer 31 and the second layer 32 are joined to each other by brazing or diffusion bonding to form an integral structure, the bonding interface between the first layer 31 and the second layer 32 is strengthened, The stress due to the difference in thermal expansion coefficient can be reliably absorbed. Therefore, reliability can be further improved.

[Second Embodiment]
FIG. 4 shows the configuration of a semiconductor laser device according to the second embodiment of the present invention. This semiconductor laser device has the same configuration as that of the first embodiment except that the third layer 33 is provided between the first layer 31 and the second layer 32 of the submount 30. is doing. Therefore, the same components are described with the same reference numerals.

  As shown in FIG. 5, the thermal expansion coefficients of the first layer 31, the third layer 33, and the second layer 32 increase in this order, and the thermal expansion coefficients with the heat sink 20 are matched in order from the LD bar 10. It is like that. That is, the third layer 33 has a thermal expansion coefficient larger than that of the first layer 31 and smaller than that of the second layer 32. Thereby, in this semiconductor laser device, the stress due to the difference in thermal expansion coefficient can be relaxed, the stress applied to the first adhesive layer 40 and the second adhesive layer 50 can be reduced, and the reliability can be improved. Yes.

  As in the first embodiment, these first layer 31 to third layer 33 are joined together by brazing or diffusion bonding to form an integral structure, and the difference in thermal expansion coefficient between these strong joint interfaces. It is possible to reliably absorb the stress caused by.

Examples of the constituent material of the first layer 31 to the third layer 33 include the following combinations.
First layer 31: Copper tungsten (CuW) (thermal expansion coefficient 6.5 × 10 ⁻⁶ [1 / K])
Third layer 33: aluminum oxide (Al ₂ O ₃ ) (thermal expansion coefficient 6.7 × 10 ⁻⁶ [1 / K]), aluminum / silicon carbide (Al / SiC) (thermal expansion coefficient 8.0 × 10 ^-6 [1 / K]), copper molybdenum (CuMo) (thermal expansion coefficient 7.0 × 10 ⁻⁶ [1 / K]), titanium (Ti) (thermal expansion coefficient 8.9 × 10 ⁻⁶ [1 / K]), beryllium (Be) (thermal expansion coefficient 11.6 × 10 ⁻⁶ [1 / K]), rhodium (Rh) (thermal expansion coefficient 8.2 × 10 ⁻⁶ [1 / K]), iron ( Fe) (thermal expansion coefficient 11.7 × 10 ⁻⁶ [1 / K]), palladium (Pd) (thermal expansion coefficient 11.8 × 10 ⁻⁶ [1 / K]), ruthenium (Ru) (thermal expansion coefficient) 9.1 × 10 ⁻⁶ [1 / K]) or nickel (Ni) (thermal expansion coefficient 14.5 × 10 ⁻⁶ [1 / K])
Second layer 32: Copper (Cu) (thermal expansion coefficient 17 × 10 ⁻⁶ [1 / K])

In the above combination, the first layer 31 may be made of iridium (Ir) (thermal expansion coefficient 6.4 × 10 ⁻⁶ [1 / K]) instead of copper tungsten (CuW). The third layer 33 can also be composed of other special function alloys.

  The total thickness of the first layer 31 to the third layer 33 is preferably 0.15 mm or more and 0.3 mm or less, for example. The thickness of each of the first layer 31 to the third layer 33 is appropriately determined so that the warp after the bonding of the first layer 31 to the third layer 33 is reduced in consideration of the respective thermal expansion coefficient and rigidity. It is desirable.

  This semiconductor laser device can be manufactured in the same manner as in the first embodiment.

  In this semiconductor laser device, when a predetermined voltage is applied between the n-side electrode 15 and the p-side electrode 14 of each laser diode chip 12, light emission occurs in the same manner as in the first embodiment. Here, since the thermal expansion coefficients of the first layer 31, the third layer 33, and the second layer 32 increase in this order, the stress due to the difference in thermal expansion coefficient is relieved, and the first adhesive layer 40 and the second adhesive layer The stress applied to 50 is reduced. Thereby, it is suppressed that the solder etc. which comprise the 1st contact bonding layer 40 and the 2nd contact bonding layer 50 will break by stress migration or quality change.

  As described above, in the semiconductor laser device of the present embodiment, the thermal expansion coefficients of the first layer 31, the third layer 33, and the second layer 32 are increased in this order. The stress applied to the first adhesive layer 40 and the second adhesive layer 50 can be reduced and the reliability can be improved. Further, the stress on the LD bar 10 can be relaxed, and a more reliable semiconductor laser device can be realized.

  In the present embodiment, the case where the submount 30 has the three-layer structure of the first layer 31, the third layer 33, and the second layer 32 has been described. However, the thermal expansion coefficients of the plurality of layers of the submount 30 are As long as the size increases from the first layer 31 toward the third layer 32, a stacked structure of four or more layers including two or more layers between the first layer 31 and the second layer 32 may be used.

[Third Embodiment]
The semiconductor laser device according to the third embodiment of the present invention is the same as that shown in FIG. 6 except that the thermal expansion coefficient of the third layer 33 is lower than that of the first layer 31. It has the same configuration as the second embodiment. Therefore, the same components are described with the same reference numerals.

  In the present embodiment, the thermal expansion coefficient of the third layer 33 is the smallest in the submount 30, and the stress due to the difference in thermal expansion coefficient is forcibly absorbed between the third layer 33 and the second layer 32. It is like that.

  Further, the first layer 31 to the third layer 33 are joined together by brazing or diffusion joining, as in the second embodiment, to form an integral structure.

Examples of the constituent material of the first layer 31 to the third layer 33 include the following combinations.
First layer 31: Copper tungsten (CuW) (thermal expansion coefficient 6.5 × 10 ⁻⁶ [1 / K])
Third layer 33: alloy (Kovar) containing iron (Fe), nickel (Ni) and cobalt (Co) (thermal expansion coefficient 5.3 × 10 ⁻⁶ [1 / K]), aluminum nitride (AlN) (heat Expansion coefficient 4.5 × 10 ⁻⁶ [1 / K]), SiSiC (thermal expansion coefficient 3 × 10 ⁻⁶ [1 / K]), silicon carbide (SiC) (thermal expansion coefficient 3.8 × 10 ⁻⁶⁾ [1 / K]), tungsten (W) (thermal expansion coefficient 4.5 × 10 ⁻⁶ [1 / K]), molybdenum (Mo) (thermal expansion coefficient 5.1 × 10 ⁻⁶ [1 / K]) , Diamond (thermal expansion coefficient 2.3 × 10 ⁻⁶ [1 / K]) or composite material of metal and diamond (composite diamond) (thermal expansion coefficient (example) 4 to 6 × 10 ⁻⁶ [1 / K] )
Second layer 32: Copper (Cu) (thermal expansion coefficient 17 × 10 ⁻⁶ [1 / K])

The following combinations are also possible.
First layer 31: silicon carbide (SiC) (thermal expansion coefficient 3.8 × 10 ⁻⁶ [1 / K])
Third layer 33: Composite material of metal and diamond (composite diamond) (coefficient of thermal expansion (example) 2.3 × 10 ⁻⁶ [1 / K])
Second layer 32: Copper (Cu) (thermal expansion coefficient 17 × 10 ⁻⁶ [1 / K])

  In particular, the third layer 33 is preferably made of a material containing diamond. The material containing diamond has a high thermal conductivity and promotes thermal diffusion not only in the vertical direction (stacking direction of the first layer 31 or the second layer 32) but also in the horizontal direction (in-plane direction of the third layer 33), This is because the heat can be spread over a wider range and the exhaust heat efficiency can be increased.

  As in the second embodiment, the total thickness of the first layer 31 to the third layer 33 is preferably set to, for example, 0.15 mm or more and 0.3 mm or less. The thickness of each of the first layer 31 to the third layer 33 is appropriately determined so that the warp after the bonding of the first layer 31 to the third layer 33 is reduced in consideration of the respective thermal expansion coefficient and rigidity. It is desirable.

  This semiconductor laser device can be manufactured in the same manner as in the first embodiment.

  In this semiconductor laser device, when a predetermined voltage is applied between the n-side electrode 15 and the p-side electrode 14 of each laser diode chip 12, light emission occurs in the same manner as in the first embodiment. Here, the thermal expansion coefficient of the third layer 33 is lower than that of the first layer 31 and is the smallest in the submount 30, and heat is forced between the third layer 33 and the second layer 32. The stress due to the difference in expansion coefficient is absorbed. Therefore, the stress applied to the first adhesive layer 40 and the second adhesive layer 50 is reduced, and the solder constituting the first adhesive layer 40 and the second adhesive layer 50 is prevented from being broken due to stress migration or alteration. Is done.

  As described above, in the semiconductor laser device according to the present embodiment, the third layer 33 has the thermal expansion coefficient lower than that of the first layer 31, and the third layer 33 and the second layer having the smallest thermal expansion coefficient in the submount 30. 32, the stress due to the difference in thermal expansion coefficient can be forcibly absorbed. Therefore, the stress applied to the first adhesive layer 40 and the second adhesive layer 50 can be reduced and the reliability can be improved. Further, the stress on the LD bar 10 can be relaxed, and a more reliable semiconductor laser device can be realized.

  In the present embodiment, the case where the submount 30 has a three-layer structure of the first layer 31, the third layer 33, and the second layer 32 has been described. However, in the present embodiment, the submount 30 is the first layer. The present invention can also be applied to a stacked structure of four or more layers including two or more layers between the layer 31 and the second layer 32. For example, as shown in FIG. 7, when the submount 30 has a four-layer structure of a first layer 31, a third layer 33, a fourth layer 34, and a second layer 32, the first layer 31, the third layer 33, The thermal expansion coefficients of the fourth layer 34 and the second layer 32 are forcibly absorbed by the fourth layer 34 and the second layer 32 by making the thermal expansion coefficients of the fourth layer 34 and the fourth layer 34 minimum. May be.

  Further, for example, as shown in FIG. 8, when the submount 30 has a four-layer structure of the first layer 31, the third layer 33, the fourth layer 34, and the second layer 32, the thermal expansion coefficient of the third layer 33. The fourth layer 34 and the second layer 32 have substantially the same thermal expansion coefficient, and the third layer 33 and the fourth layer 34 are forcibly absorbed by the difference in thermal expansion coefficient. You may make it make it.

[Fourth Embodiment]
FIG. 9 shows the configuration of a semiconductor laser device according to the fourth embodiment of the present invention. This semiconductor laser device is a water-cooled type in which a water-cooling mechanism 21 is provided in a region corresponding to the LD bar 10 of the heat sink 20, and an insulating material is provided between the first layer 31 and the second layer 32 of the submount 30. Except that the third layer 33 is provided, it has the same configuration as the second or third embodiment. Therefore, the same components are described with the same reference numerals.

  The water cooling mechanism 21 is a micro-channel type having a water channel (not shown) provided with fins in a region directly under the LD bar 10, and high heat exhaust efficiency is realized by flowing water through that portion. Yes.

  The third layer 33 is made of an insulating material such as ceramic. As a result, in this semiconductor laser device, the LD bar 10 and the heat sink 20 are electrically separated so that water leakage due to corrosion (erosion) of the metal material in the vicinity of the fins of the water cooling mechanism 21 can be suppressed. It has become. Further, the same effect as that of the second or third embodiment can be obtained by the thermal expansion coefficient of the insulating material constituting the third layer 33.

  The electrical connection to the surface of the LD bar 10 on the submount 30 side can be made by the first layer 31 or a metal coating layer (not shown) provided on the surface thereof. Therefore, it is desirable to make the submount 30 larger.

  This semiconductor laser device can be manufactured in the same manner as in the first embodiment.

  In this semiconductor laser device, when a predetermined voltage is applied between the n-side electrode 15 and the p-side electrode 14 of each laser diode chip 12, light emission occurs in the same manner as in the first embodiment. Here, a water cooling mechanism 21 is provided in a region corresponding to the LD bar 10 of the heat sink 20, and the LD bar 10 is cooled by the water cooling mechanism 21. In addition, since the third layer 33 made of an insulating material is provided between the first layer 31 and the second layer 32 of the submount 30, the LD bar 10 and the heat sink 20 are electrically separated, and the water cooling mechanism. Corrosion of the metal material in the vicinity of the fin 21 is suppressed.

  Furthermore, in the case of a stack type in which a plurality of semiconductor laser devices are two-dimensionally stacked, the potential difference between the adjacent or upper and lower heat sinks 20 is eliminated, and electrical corrosion is suppressed. Therefore, there is no risk of the occurrence of water loss due to the occurrence of thinning in the vicinity of the water channel. In addition, conventional countermeasures such as increasing the purity of the cooling water and reducing the conductivity to prevent electrical corrosion are not necessary, and complicated management is not required.

  As described above, in the semiconductor laser device of the present embodiment, the water cooling mechanism 21 is provided in the region corresponding to the LD bar 10 of the heat sink 20, and the insulating material is provided between the first layer 31 and the second layer 32 of the submount 30. Since the third layer 33 is provided, in addition to the effects of the second or third embodiment, the exhaust heat efficiency can be further increased, and leakage due to corrosion of the heat sink 20 can be suppressed. Particularly, it is suitable for the stack type, and it is possible to further increase the output.

  In the present embodiment, the case where the submount 30 has a three-layer structure including the first layer 31, the third layer 33, and the second layer 32 has been described. However, the submount 30 includes the first layer 31 and the second layer 32. A stacked structure of four or more layers including two or more layers between the layers 32 may be used. Even in this case, the first layer 31 may be electrically connected to the LD bar 10 and at least one layer other than the first layer 31 may be made of an insulating material.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the material and thickness of each layer, the film formation method, and the film formation conditions described in the above embodiment are not limited, and other materials and thicknesses may be used. It is good also as conditions. For example, in the above-described embodiment, the infrared laser having the semiconductor layer 13 made of an AlGaAs compound semiconductor on the substrate 11 made of GaAs has been described as an example. However, the present invention is not limited to other devices such as an AlGaInP system or a GaN system. It can also be applied to material systems.

  Further, for example, in the above embodiment, the first adhesive layer 40 and the second adhesive layer 50 are not limited to brazing or gold (Au) -tin (Sn) solder, but may be composed of other solder materials. . For example, a solder containing no lead (lead-free solder) such as one containing tin (Sn) as a main component, one containing indium (In), or one containing gold (Au) is preferable, but a lead-based solder may be used. .

  Furthermore, the present invention can also be applied to the case where the laser characteristics are improved by intentionally providing a difference in thermal expansion coefficient between the LD bar 10 and the submount 30. In that case, what is necessary is just to combine the constituent material of each layer of the submount 30 so that a specific thermal expansion coefficient difference can be ensured.

  In addition, although the semiconductor laser has been described as an example in the above embodiment, the present invention can be applied to other semiconductor light emitting elements such as a superluminescent diode in addition to the semiconductor laser.

1 is an exploded perspective view showing a configuration of a semiconductor laser device according to a first embodiment of the present invention. It is the perspective view which expanded and represented a part of LD bar | burr shown in FIG. It is a figure showing the thermal structure of the semiconductor laser apparatus shown in FIG. It is a disassembled perspective view showing the structure of the semiconductor laser apparatus which concerns on the 2nd Embodiment of this invention. FIG. 5 is a diagram illustrating a thermal configuration of the semiconductor laser device illustrated in FIG. 4. It is a figure showing the thermal structure of the semiconductor laser apparatus which concerns on the 3rd Embodiment of this invention. It is a figure showing the thermal structure of the semiconductor laser apparatus which concerns on the modification of 3rd Embodiment. It is a figure showing the thermal structure of the semiconductor laser apparatus which concerns on another modification. It is a disassembled perspective view showing the structure of the semiconductor laser apparatus which concerns on the 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LD bar | burr, 11 ... Board | substrate, 12 ... Laser diode chip, 13 ... Semiconductor layer, 14 ... P side electrode, 15 ... N side electrode, 20 ... Heat sink, 21 ... Water cooling mechanism, 30 ... Submount, 31 ... 1st 32, second layer, 33, third layer, 40, first adhesive layer, 50, second adhesive layer

Claims (10)

A semiconductor laser element;
A heat dissipating member having a larger thermal expansion coefficient than the semiconductor laser element;
A first layer having a thermal expansion coefficient substantially equal to that of the semiconductor laser element and disposed on the surface on the semiconductor laser element side, and a thermal expansion coefficient substantially equal to that of the heat dissipation member and disposed on the back surface on the heat dissipation member side. A support member having a laminated structure of a plurality of layers including the second layer, and the plurality of layers being joined together by brazing or diffusion bonding;
A first adhesive layer that joins the semiconductor laser element and the support member;
A semiconductor laser device comprising: a second adhesive layer that joins the heat dissipation member and the support member. The semiconductor laser device according to claim 1, wherein the support member has a coefficient of thermal expansion of the plurality of layers that increases in order from the first layer toward the second layer. The said support member has a 3rd layer whose thermal expansion coefficient is larger than the said 1st layer and smaller than the said 2nd layer between the said 1st layer and the said 2nd layer. The semiconductor laser device described. The support member forcibly absorbs stress due to a difference in thermal expansion coefficient between a layer having the smallest thermal expansion coefficient among the plurality of layers and a layer laminated on the heat dissipation member side of the layer. The semiconductor laser device according to claim 1. The semiconductor laser device according to claim 4, wherein the support member includes a third layer having a thermal expansion coefficient smaller than that of the first layer between the first layer and the second layer. The semiconductor laser device according to claim 1, wherein at least one of the plurality of layers is made of a material containing diamond. The heat radiating member includes a water cooling mechanism in a region corresponding to the semiconductor laser element,
The semiconductor laser device according to claim 1, wherein at least one of the plurality of layers other than the first layer is made of an insulating material. The semiconductor laser element is formed on a substrate made of GaAs, and the first layer is made of at least one of copper tungsten (CuW), iridium (Ir), and silicon carbide (SiC). The semiconductor laser device according to claim 1. The semiconductor laser device according to claim 1, wherein the heat dissipation member and the second layer are made of copper (Cu). The semiconductor laser device according to claim 1, wherein the first adhesive layer and the second adhesive layer are made of brazing or gold (Au) -tin (Sn) solder.

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