JP2011014558A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device capable of precisely adjusting output of laser light with a small amount of variation in Im value (photocurrent value of a light receiving element).SOLUTION: The semiconductor laser device includes: a semiconductor laser element having a first electrode provided on a reverse surface of a substrate, a semiconductor layer provided on a top surface of the substrate, and a second electrode provided on a top surface of the semiconductor layer; and a light receiving element which receives light output from the semiconductor laser element. In the semiconductor laser device, the first electrode is provided having an exposed region partially on the reverse surface of the substrate, the light receiving element is arranged having a light receiving surface opposed to the exposed region, and the exposed region is formed in a region not right below a waveguide.

Description

  The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device having a light receiving element in the device.

One of the laser driving methods is APC (Auto Power Control) driving. APC driving is a driving method used when the laser output is constant. In this case, since the laser output needs to be monitored, a light receiving element (photodiode, PD) is built in the laser device. Sometimes. A constant output can be maintained by feeding back to the current value injected into the laser while using the current value (hereinafter referred to as Im value) flowing when the light receiving element receives light.
2. Description of the Related Art Conventionally, a semiconductor laser device in which a laser element and a light receiving element that monitors laser light output from the laser element to the rear side are used is used (see, for example, Patent Document 1 and Patent Document 2). In addition, there is a method for monitoring leakage light by providing an opening in an electrode (for example, Patent Document 3).

Japanese Patent Laying-Open No. 2003-229630 (paragraphs 0021-0025, FIG. 1) Japanese Patent Laying-Open No. 2003-60276 (paragraphs 0008, 0021, 0023, FIG. 3) JP-A-6-204603 (paragraphs 0013-0014, FIG. 2)

  In Patent Documents 1 and 2, a light receiving element is disposed behind the reflecting surface of the semiconductor laser element, and laser light output from the reflecting surface of the semiconductor laser element is received. In such a structure, depending on the mounting position and mounting angle of the light receiving element, the laser light may be reflected by the light receiving element and the stem in the semiconductor laser device, and the diffused laser light may be received. When this occurs, the amount of light cannot be measured with high accuracy, and it is difficult to reflect the Im value obtained from the light receiving element during APC driving in the current value injected into the laser element. In Patent Document 3, such a problem can be solved. However, since a hole for light leakage is provided immediately above the waveguide, the heat dissipation performance directly above the waveguide is deteriorated. As a result, the temperature of the element rises and the temperature inside the apparatus also rises, so that the deviation from the current value that should flow with the received light quantity (change in Im value) tends to increase, and an accurate Im value is given to the laser element. It cannot be fed back to the current value to be injected. Further, by providing a hole for light leakage directly above the waveguide, there is a problem that current injection into the waveguide becomes non-uniform and adversely affects the characteristics of the laser element.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor laser device in which the amount of change in Im value is small and the output of laser light can be adjusted with high accuracy.

A semiconductor laser device of the present invention includes a semiconductor laser element having a first electrode provided on the back surface of a substrate, a semiconductor layer provided on the surface of the substrate, and a second electrode provided on the surface of the semiconductor layer;
In a semiconductor laser device having a light receiving element that receives light output from the semiconductor laser element, the first electrode is provided so as to partially include an exposed region on the back surface of the substrate, and the light receiving element is The light receiving surface is disposed so as to face the exposed region, and the exposed region is formed in a region other than directly under the waveguide.
Another semiconductor laser device of the present invention includes a semiconductor laser element having a first electrode provided on the back surface of a substrate, a semiconductor layer provided on the surface of the substrate, and a second electrode provided on the surface of the semiconductor layer. And a light receiving element that receives light output from the semiconductor laser element, wherein the second electrode is provided so as to partially include an exposed region on a surface of the semiconductor layer, and The element is disposed such that the light receiving surface faces the exposed region, and the exposed region is formed in a region other than directly under the waveguide.
The exposed area is preferably defined by a notch provided in the electrode.
The exposed region is preferably formed in a central region in the resonator direction.
The semiconductor laser device preferably includes a support member on which the semiconductor laser element is placed, and the laser element is disposed across the light receiving element and the support member.
Moreover, it is preferable to have a space between the light receiving element and the support member.
Further, it is preferable that a support member is disposed on the emission surface side of the semiconductor laser element, and a light receiving element is disposed on the reflection surface side.
The semiconductor laser element is preferably mounted junction-down.
Moreover, it is preferable that the said exposed area | region opposes a light-receiving surface through the translucent insulating film provided in the surface of the said semiconductor layer.

  According to the semiconductor laser device of the present invention, the electrode is provided so as to have an exposed region in a region other than directly below the waveguide, and the light receiving element is disposed so that the exposed region and the light receiving surface of the light receiving element face each other. The amount of change in the Im value is small, and the output of the laser beam can be adjusted with high accuracy.

It is a top view of the semiconductor laser apparatus of this invention. It is an enlarged view of the principal part of the semiconductor laser apparatus of this invention. It is sectional drawing of the semiconductor laser apparatus of this invention. It is an enlarged view of the principal part of the semiconductor laser apparatus of this invention. It is sectional drawing of the semiconductor laser apparatus of this invention. 1 is a perspective view of a semiconductor laser device of the present invention. It is a top view of another semiconductor laser device of the present invention. It is a top view of another semiconductor laser device of the present invention. It is the top view of another semiconductor laser apparatus of this invention, sectional drawing, and an enlarged view.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring drawings. However, the form shown below is an example, and the present invention is not limited to the following, and the present invention is not limited to the dimensions, materials, shapes, relative arrangements, and the like of the components described. Absent. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. In order to simplify the description, the same constituent elements are denoted by the same reference numerals, and a part of the description is omitted.

<First Embodiment>
1 to 4 show an example of the semiconductor laser device of the present invention. FIG. 1 is a plan view of the semiconductor laser device of the present invention as viewed from above, and FIG. 2 is an enlarged view of a circled portion in FIG. 3A is a cross-sectional view taken along line II ′ of FIG. 1, FIG. 3B is a cross-sectional view taken along line II-II ′ of FIG. 1, and FIG. 3C is a cross-sectional view taken along line III-III ′. FIG. 4 is an enlarged view of the encircled portion in FIG.
In the semiconductor laser device 100 of the present invention, for example, as shown in FIG. 1, a semiconductor laser element 10 having a pair of resonator surfaces 13 a and 13 b is placed on a light receiving element 20 and a support member 30. As shown in FIG. 3, the semiconductor laser element has a semiconductor layer 10c formed on a substrate 10b. A first electrode 11a is provided on the back surface of the substrate 10b. Is provided so as to be partially provided on the back surface of the substrate 10b. Further, as shown in FIG. 3B, the light receiving element 20 is arranged so that the exposed region 10a and the light receiving surface 21 of the light receiving element 20 face each other, and the exposed region is provided in a region other than directly under the waveguide. .

Each configuration of the present invention will be described.
(Semiconductor laser element)
The semiconductor laser element 10 includes a first electrode 11a provided on the back surface of the substrate 10b, a semiconductor layer 10c provided on the surface of the substrate, and a second electrode 11b provided on the surface of the semiconductor layer.
In a semiconductor laser device, when a voltage is applied and a current exceeding a threshold value flows, laser oscillation occurs in and around the active layer, and the generated laser light is emitted outside through the waveguide region 14. Any of the known ones may be used. In addition, the semiconductor material may use any compound such as III-V group or II-VI group, and may emit laser light of any wavelength. In particular, in a short wavelength semiconductor material (nitride semiconductor), the wavelength and efficiency fluctuate easily due to a change in ambient temperature. Therefore, it is necessary to increase the monitoring accuracy of the light receiving element and reduce the temperature dependency. Therefore, it is effective to apply the present invention to a laser element using a nitride semiconductor and a laser element emitting a laser beam having a wavelength of about 325 to 550 nm.

  The substrate is preferably a conductive substrate on which an electrode can be formed on the back surface. Specific examples include nitride semiconductor substrates (GaN, AlN, etc.). The substrate may have an off angle of about 0 ° to 10 ° on its surface. The film thickness is preferably about 50 μm to 10 mm. In addition, an underlayer or the like may be arbitrarily formed before the semiconductor layer is grown.

As the semiconductor layer, for example, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked from the substrate side. The semiconductor layer is preferably, for example, a material represented by the general formula In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).
Although the film thickness of a semiconductor layer is not specifically limited, As for an n-type semiconductor layer, about 0.2-12 micrometers, an active layer is about 15-300 nm, and a p-type semiconductor layer is about 60-120 nm.
Semiconductor layer growth methods include nitride semiconductor growth such as MOVPE (metal organic chemical vapor deposition), MOCVD (metal organic chemical vapor deposition), HVPE (hydride vapor deposition), MBE (molecular beam epitaxy). A known method can be used.

  The waveguide region 14 may be provided by any known method such as a ridge structure, a current confinement layer formed on the surface of the semiconductor layer, or a striped electrode. In this specification, for convenience of explanation, the width of the waveguide region of the ridge waveguide type semiconductor laser element is described as corresponding to the width of the ridge. The width of the waveguide region of the semiconductor laser element in which the waveguide region is defined by the current confinement layer corresponds to the width of the opening of the current confinement layer, and the semiconductor laser in which the waveguide region is defined by the striped electrode The width of the waveguide region of the element corresponds to the width of the electrode.

  Further, the position of the waveguide region of the semiconductor laser element is not limited within the element. As shown in FIGS. 1 and 3, by arranging the waveguide region so as to be shifted from the center in the width direction of the element, a notch with a desired size can be provided in the electrode, so that light is incident on the light receiving element. It becomes easy. In the case of a ridge waveguide type semiconductor laser device, it is effective to dispose the waveguide region from the center in the width direction of the device from the viewpoint of securing a region for wire bonding on the surface of the laser device. That is, when the waveguide region 14 is defined by the ridge 12, the ridge is not necessarily arranged at the center, and may be arranged close to one of the side surfaces.

  Moreover, the mounting method of a laser element is not specifically limited, Junction up mounting or junction down mounting can be used. Since a member such as an insulating film or an electrode is generally formed on the surface of the laser element, it is preferable to perform junction-up mounting from the viewpoint of easily forming an exposed region.

  Further, the semiconductor laser device may have one or a plurality of semiconductor laser elements. In the case of an apparatus having a plurality of laser elements, semiconductor laser elements having the same wavelength band may be used, or semiconductor laser elements having different wavelength bands may be used. By using the same wavelength band, a high-power laser device can be obtained. In addition, by using red, blue, and green laser elements, light of various colors can be obtained or mixed to obtain white light. In addition, by using a laser element having a wavelength band of 780 nm, 650 nm, and 405 nm, a semiconductor laser device capable of reproducing and / or writing CD, DVD, and Blu-ray Disc can be obtained. Moreover, the light receiving element and / or supporting member to be used may be singular or plural. When a plurality of light receiving elements are used, it is not necessary that all the light receiving elements are arranged to receive the light emitted from the exposed region, and at least one may be arranged as in the present invention. When a plurality of semiconductor laser elements are used, they may be disposed on the same light receiving element and / or support member, or may be disposed on different support members. Further, they may be arranged separately on the support member, and the other two laser elements are formed as one element on one laser element arranged on the support member. An integrated laser element may be disposed, or vice versa.

(electrode)
The electrode includes a first electrode 11a formed on the back surface of the substrate of the semiconductor laser element, and a second electrode 11b formed on the surface of the semiconductor layer. In this specification, unless otherwise specified, it is described as “electrode” as a comprehensive expression of the first electrode and the second electrode. As a material of the electrode, a known material can be appropriately used. For example, vanadium, palladium, platinum, nickel, gold, titanium, tungsten, copper, silver, zinc, tin, indium, aluminum, iridium, rhodium, ITO, etc. It can be formed of a single layer film or a laminated film of the above metals or alloys. Specifically, an electrode having a laminated structure such as V / Pt / Au, Ti / Pt / Au, Ni / Ti / Au, or Ni / Pd / Au can be used. The film thickness of the electrode can be appropriately adjusted depending on the material used, and for example, about 500 to 5000 mm is appropriate. Further, one or a plurality of conductive layers may be formed on or below this electrode.

  Moreover, the 1st electrode in this invention is provided so that the back surface of the board | substrate of a laser element may be exposed partially. The light output from the exposed region is received by a light receiving element arranged to face the exposed region. The semiconductor laser element in this embodiment is electrically connected to the outside by a first electrode provided on the back surface of the laser element. An electrode that is often formed of a metal material reflects light output from the laser element and cannot be output to the outside of the element. However, as shown in FIGS. The light receiving element can receive the light by exposing the light and extracting light from the exposed region.

For example, as shown in FIG. 2, the light receiving element is disposed so that the light receiving surface faces the exposed region 10 a provided in the electrode 11 with a length H and a width W in the resonator direction. At this time, the exposed region may be provided in such a size that the light receiving element can monitor the light from the laser element. For example, as shown in FIG. 2, the length H of the exposed region in the resonator direction is about ^{5 to} 1500 μm, the length W in the width direction is about 10 to 1000 μm, and the area is 50 μm ^{2 to} 1.5 mm. ^It is sufficient that about ^two are provided. From another point of view, about 5 to 50% of the back surface of the substrate or the surface of the semiconductor layer may be exposed.

  The exposed region is provided in a region other than directly under the waveguide. Preferably, the exposed region is spaced 5 μm or more from directly below the waveguide, but the portion below the waveguide may be exposed within a range not impairing the operational effects of the present invention. “Directly under” refers to “directly under” the direction in which the light receiving element is located with respect to the waveguide region regardless of whether the mounting state of the semiconductor laser element is junction-up mounting or junction-down mounting. When the Im value fluctuates due to a change in ambient temperature, it becomes difficult for the semiconductor laser device to accurately feed back the current value injected into the laser element, and the laser output cannot be kept constant. When the semiconductor laser device is APC driven using the light receiving element, the amount of change in the Im value tends to increase as the temperature increases. Further, the heat generated by the laser element is dissipated from the light receiving element, the support member, and the stem to the outside of the apparatus through the electrodes. In the laser element, since current and light concentrate in the waveguide region, the light density in the waveguide region is enormous, and heat generation is significant in the waveguide region and immediately below it. Therefore, if an exposed region is provided in the region directly under the waveguide, the heat dissipation path for the heat generated in the waveguide region will be cut off, and the element temperature will rise further without being radiated, resulting in a higher temperature in the device. . Therefore, by providing the exposed region away from the portion immediately below the waveguide, the heat generated in the waveguide region can be suitably released to the outside of the device, and the rise in device temperature can be suppressed. A semiconductor laser device can be obtained in which the fluctuation of the laser beam can be reduced, and the amount of change in the Im value is small and the output of the laser beam can be adjusted accurately by arranging the light receiving element so as to face the exposed region. Is possible. In addition, if an exposed region is provided on the waveguide region, laser characteristics such as threshold and beam shape may be affected due to factors such as non-uniformity of current injection and instability of optical confinement in the cavity direction. Although it is considered, these can be suppressed.

  Moreover, it is preferable to arrange the exposed region so that spontaneous emission light is output from the exposed region. Since laser light (stimulated emission light) has a high light density, when an exposed region is arranged so as to receive laser light, the Im value changes greatly even if slight fluctuations occur in the output light. However, the fluctuation of the Im value can be prevented by receiving the spontaneous emission light. Since laser light is guided directly under the waveguide, it is effective to provide an exposed region in a region other than directly under the waveguide from this viewpoint.

  Further, the exposed region can be provided, for example, on the reflective surface (13b in FIG. 1) side of the semiconductor laser element. Thereby, while ensuring the quantity of the light discharge | released from an exposure area | region, it can radiate | emit heat through an electrode in the output surface side with big heat_generation | fever. That is, the exposed region is preferably provided in a region other than the vicinity of the exit surface (13a in FIG. 1) side, and particularly preferably formed in the central region in the resonator direction. The “central region in the direction of the resonator” refers to a region other than the vicinity of the resonator surface, and is preferably separated from the resonator surface by 10 μm or more. As a result, an exposed region can be provided while avoiding a region having a high light density, and thus fluctuations in the Im value can be suppressed.

  Moreover, as shown in FIG. 1, the exposed region is preferably defined by a notch provided in the electrode. Both functions of current injection and efficient light reception on the light receiving surface can be performed effectively. Further, as shown in FIG. 7, it may be provided by making the size of the electrode smaller than the size of the back surface of the substrate, or may be provided so as to expose the outer periphery of the semiconductor laser element. As such, it may be combined with a notch. By exposing the outer periphery of the element, it can be used as a mark when the element is divided. Further, it is possible to suppress a division failure during element division.

  A method for forming the electrode is not particularly limited, but sputtering, vapor deposition, and the like are preferably used. In addition, as a patterning method of the electrode for providing the exposed region and the cutout portion, a known method such as a lift-off method or etching using photolithography (dry etching or wet etching) can be used.

(Light receiving element)
The light receiving element 20 receives light output from the semiconductor laser element 10 and is composed of, for example, a PIN photodiode or PN photodiode using silicon. The light receiving element may be composed of either a P-type semiconductor or an N-type semiconductor.
In the present invention, the light receiving element 20 is installed by adjusting the light receiving surface 21 of the light receiving element 20 so as to face the exposed region provided on the substrate so as to receive light emitted from the laser element.
The size of the light receiving element is not particularly limited, and a light receiving element having a size of about 0.04 to ³ mm ² can be used. The light receiving surface may have a size of about 0.01 to 2.9 mm ² . The thickness of the light receiving element is preferably about the same as that of a support substrate described later or thinner than the support substrate. The size of the light receiving element is preferably larger than the width of the laser element from the viewpoint of ease of assembly. In particular, as shown in FIG. 8, when a light receiving element whose resonator direction and width are both larger than that of a semiconductor laser element is used, it becomes possible to assemble a semiconductor laser device without using other members, and a simple configuration. A semiconductor laser device can be obtained. The light receiving surface is preferably larger than the exposed region provided in the laser element. In order to facilitate electrical wiring, an insulating layer made of an electrode, an oxide film, or a nitride film may be formed on the upper surface or the light receiving surface of the light receiving element.

The semiconductor laser element and the light receiving element are preferably bonded using an adhesive layer 15 as shown in FIG. Here, the term “adhered” means, for example, that the contact area between the two is bonded with an area of about 20% or more of the area of the electrode, and thereby the mounting strength can be ensured. Although it is preferable that it is bonded with an adhesive layer such as a solder material, the electrode described above can also be used. Moreover, the method etc. normally used in the said field | area etc. can be utilized for the adhesion | attachment method, such as the method of adhere | attaching by hold | maintaining under predetermined temperature and pressure after match | combining a joint surface. Specific examples include a thermocompression bonding method and a direct bonding method.
The bonding surface between the semiconductor laser element and the light receiving element may be provided on the light receiving surface or may be provided in another region. From the viewpoint of heat dissipation, as shown in FIG. 8, use a light receiving element that does not have a light receiving surface on the surface of the light receiving element that does not face the exposed region, and adheres to a region other than the light receiving surface. It is preferable to secure the area. Or it is preferable to provide the support member mentioned later and to make it adhere | attach with a support member.

  Solder materials used for the adhesive layer include Au—Sn, Sn—Pb, Sn, Au, In, Bi, Cd, Zn, Sn—Zn, Cd—Zn, and In—Pb. Examples thereof include simple substances such as Zn, Ag, Cu, Ni, and Sb, or eutectic materials.

<Second Embodiment>
FIG. 9 shows an example of another semiconductor laser device of the present invention. 9A is a plan view of the semiconductor laser device of the present invention as viewed from above, FIG. 9B is a cross-sectional view taken along line II ′ of FIG. 1, and FIG. 9C is FIG. It is an enlarged view of a circled part in the inside.
In the semiconductor laser device 100 of the present embodiment, for example, as shown in FIG. 9, the semiconductor laser element 10 is placed on the light receiving element 20 and the support member 30. The second electrode 11b is provided on the surface of the semiconductor layer 10c, and the second electrode 11b is provided so as to partially include the exposed region 10a defined by the notch 16 on the surface of the semiconductor layer 10c. ing. As shown in FIG. 3B, the light receiving element is arranged so that the exposed region 10a and the light receiving surface 21 of the light receiving element 20 face each other, and the exposed region is provided in a region other than directly below the waveguide. That is, the semiconductor laser device of the present embodiment is mounted junction-down, thereby improving the heat dissipation of the semiconductor laser element.

  The second electrode 11b is provided on the surface of the semiconductor layer, and is provided so as to partially expose the surface of the semiconductor layer. The light output from the exposed region is received by a light receiving element arranged to face the exposed region. The semiconductor laser device in this embodiment is electrically connected to the outside by the second electrode. The function, material, film thickness, formation method, and the like are the same as those of the first electrode as described above.

In addition, an insulating film 17 is preferably formed on the surface of the semiconductor layer. In addition, as shown in FIG. 9C, in the case where an exposed region is provided on the surface of the semiconductor layer, it is preferable that the light receiving surface and the semiconductor layer face each other with a light-transmitting insulating film interposed therebetween. This is to protect the surface of the semiconductor layer and prevent current leakage.
Specific examples of the insulating film include oxides such as SiO ₂ , Ga ₂ O ₃ , Al ₂ O ₃ , and ZrO ₂ , and nitrides such as SiN, AlN, and AlGaN. The film thickness is about 0.01 to 5 μm, preferably about 0.02 to 1 μm.
The insulating film can be formed by a method known in the art. For example, vapor deposition, sputtering, reactive sputtering, ECR plasma sputtering, magnetron sputtering, and the like can be given.
As a method for forming the exposed region, a known method can be used. However, patterning is performed by a lift-off method, etching using photolithography (dry etching or wet etching), and the exposed region is provided. It is preferable.

Hereinafter, other configurations will be described.
5 and 6 show an example of the semiconductor laser device of the present invention. FIG. 5 is a sectional view in the cavity direction, and FIG. 6 is a perspective view of the entire laser device.
FIG. 5 shows the semiconductor laser device of FIG. 1 mounted on the stem 40, and FIG. 6 shows the semiconductor laser device of FIG. In the semiconductor laser device 100 shown in FIG. 6, a cylindrical cap 42 is bonded to a stem 40 having leads 41, an opening is formed on the top of the cap, and a cap glass 43 is bonded to the opening. The laser beam can be extracted from the cap glass. As shown in FIG. 5, the semiconductor laser element 10 is placed on the stem 40 via the light receiving element 20 and the support member 30 inside the cap. A lead 41 is provided so as to penetrate the stem, and wire bonding (not shown) is performed so as to energize through the lead.

(Support member)
The support member 30 in the present invention is also referred to as a submount, and maintains the close contact and heat dissipation of the semiconductor laser element, the support member, and the stem, and plays a role of releasing generated heat. What can be done is preferred. Moreover, it is preferable that the support member also has a function of alleviating breakage due to strain caused by a difference in thermal expansion coefficient between the stem and the semiconductor laser element.
A surface of the support member on which the semiconductor laser element is placed may be referred to as an upper surface, and a surface bonded to the stem may be referred to as a lower surface.
The shape of the support member is not particularly limited as long as it functions as described above, and can be appropriately processed into an arbitrary shape and used. Specifically, it is preferable in terms of ease of assembly of the semiconductor laser device that it is formed in a shape such as a rectangular parallelepiped or a cube, or a shape similar to these.
The material of the support member is a semiconductor laser element (particularly a substrate constituting the element, such as GaN) having a thermal expansion coefficient close to (for example, about ± 15 / K), or a material that can relieve thermal stress. Etc. Specific examples include silicon, silicon carbide (SiC), aluminum nitride (AlN), Cu, CuW, CuMo, and the like. Preferably, it is made of AlN.

In the present invention, when the semiconductor laser element and the light receiving element to be used are unstable in the assembly of the semiconductor laser device, the support member can play a role of complementing it. In other words, the semiconductor laser element is preferably disposed across the light receiving element and the support member. For example, as shown in FIG. 1, when the size of the light receiving element is shorter than the resonator length of the semiconductor laser element, it is difficult to maintain the strength of the device itself only by mounting the semiconductor laser element on the light receiving element. From the viewpoint of heat dissipation of the semiconductor laser element, it is not preferable. In such a case, it is preferable to use a support member because the strength and heat dissipation of the semiconductor laser device can be improved. Moreover, the heat dissipation can be improved by using a material with higher thermal conductivity than the light receiving element.
In this case, the contact area between the laser element and the support member is about 100 to 1500 μm in length in the cavity direction, about 40 to 1000 μm in length in the width direction, and about 0.04 to 1.5 mm ² in area. If they are in contact with each other, the strength of the bonding between the two can be maintained, which is preferable.

  The size of the support member in such a case is not particularly limited, but preferably has a larger width than the semiconductor laser element to be mounted. Further, it is preferable to use a support member in which the total area of the planar sizes of the light receiving element and the support member is larger than the planar size of the semiconductor laser element. The size of the support member can be appropriately adjusted depending on the size of the semiconductor laser element to be used, the size of the stem to be mounted, the size of the semiconductor laser device to be finally obtained, the material of the support member, and the like. For example, the thickness is about 1 to 5 times that of the semiconductor laser element, and the planar size is about 1 to 30 times that of the semiconductor laser element. Specifically, it is preferably about 100 to 2000 μm in the cavity direction of the semiconductor laser element, about 50 to 1000 μm in the width direction, and about 50 to 500 μm in the thickness direction.

  When using a support member, as shown in FIG. 1, it is preferable to arrange the support member on the emission surface 13a side of the semiconductor laser element and arrange the light receiving element on the reflection surface 13b side. This is because by disposing the light receiving element on the reflecting surface side, while ensuring the amount of light emitted from the exposed region, it is possible to radiate heat suitably through the support member on the emitting surface side where heat is generated. In particular, in the junction down mounting, it is preferable that the support member be disposed so that the side surface of the support member does not protrude from the emission surface when the semiconductor laser device is viewed from the upper surface side of the laser element. This is to prevent the laser beam from hitting the upper surface of the support member and disturbing the beam shape.

  Further, when the support member and the light receiving element are arranged side by side, it is preferable that the gap 32 is formed between the support member and the light receiving element as shown in FIG. When mounting the support member and the light receiving element, since two members are mounted, there is a problem that a step or a positional deviation is likely to occur depending on the mounting conditions, and extremely high mounting accuracy is required. Moreover, after mounting one member, when mounting a light receiving element, it may come into contact with the support member and cause a shift. By arranging the gaps so as to create a gap, it is possible to prevent steps and displacement and to extract laser light in a desired direction.

Moreover, it is preferable that a conductive member is formed on the upper surface and / or the lower surface of the support member in order to energize the laser element and the stem and to improve heat dissipation. Examples of the conductive member include a single layer film, a multilayer film, and an alloy made of a metal such as Ti, Pt, and Au. Preferably, a laminated film of Ti / Au / Pt / Au or Ti / Pt / Au can improve the thermal resistance and the adhesion between the semiconductor laser element and the stem in contact with the support member. The conductive member is preferably formed on substantially the entire surface of the laser mounting surface and the adhesive surface with the stem.
Further, the semiconductor laser element and the supporting member can be bonded using the same method as the above-described bonding method between the semiconductor laser element and the light receiving element.

(Stem)
In the semiconductor laser device of the present invention, it is preferable that the light receiving element and the support member are placed on a stem. The stem 40 is effectively used to efficiently release the heat generated by the semiconductor laser element to the outside through the support member, also called a heat sink. The stem is preferably formed of a material having a high thermal conductivity, for example, a material of about 40 W / mK or more. Specific examples include metals such as Cu, Al, Fe, Ni, Mo, CuW, and CuMo, and materials obtained by plating at least one surface of these metals with Au, Ag, Al, or the like. Especially, what is formed with the copper or copper alloy by which the surface was gold-plated is preferable. The shape and size of the stem are not particularly limited, and can be appropriately adjusted according to the final desired shape and size of the semiconductor laser device.

In particular, as a bonding material between the stem and the light receiving element and / or the support member, a high melting point material of 250 ° C. or higher, an Au-based low melting point solder material (for example, Au / Sn, Ni / Au, Ni / Pd / Au, etc.), bonding resin Stable bonding can be obtained by bonding using die (die bonding).
Further, the contact area between the stem and the light receiving element and / or the support member is preferably bonded with an area of about 70% or more of the planar size of the light receiving element and / or the support member. As the bonding method, the same method as the bonding of the semiconductor laser element and the light receiving element described above can be used. Also, any other known method may be used.

  The method for assembling the semiconductor laser device of the present invention is not particularly limited. For example, the light receiving element and the support member are placed on and adhered to the stem, and then the semiconductor laser element is mounted on the light receiving element and the support member. The method to adhere | attach is mentioned. Assembling by this method is preferable because it can be mounted easily and stably. Alternatively, a method may be used in which a semiconductor laser element is bonded on the light receiving element and the support member, which is mounted on the stem and bonded.

(cap)
The semiconductor laser element is hermetically sealed by a cap 42, and usually covers the semiconductor laser element and is bonded to the stem by resistance welding, soldering, or the like. The cap is preferably formed of, for example, a material having high thermal conductivity. For example, various materials such as Ni—Fe alloy, Kovar, Ni, Co, Fe, and brass can be used.
Examples of the shape of the cap include various shapes such as a bottomed cylindrical shape (such as a cylinder or a polygonal column) or a frustum shape (such as a truncated cone or a polygonal frustum), a dome shape, and deformed shapes thereof. . Of these, a cylinder is preferable.
The cap has a through-hole through which light from the light emitting element passes in a portion facing the light emitting portion of the light emitting element, depending on the mounting form of the light emitting element on the stem. Therefore, the through hole may be formed in any part such as the upper surface or the side surface of the cap. A translucent member is supported in the through hole.

The light transmissive member is a member that allows light from the light emitting element to pass through, and thereby, laser light can be extracted. The translucent member has a low absorptance of light emitted from the semiconductor laser element, in other words, can transmit 60% or more, 85% or more, and further 99% or more of the light emitted from the light emitting element. Is preferred. For example, it can be formed from borosilicate glass, glass, quartz glass, sapphire, ceramic (ZrO ₂ , Al ₂ O ₃ , AlN, GaN, etc.), resin (silicone resin, epoxy resin, etc.), or a combination thereof. Further, a light transmissive film may be provided on the surface so that the laser light can be suitably transmitted. Moreover, the translucent member may contain the wavelength conversion member, the light-diffusion material, etc. As the wavelength conversion member and the light diffusing material, any of those used in the field may be used.

  The atmosphere for sealing the semiconductor laser element with the cap is not particularly limited. However, in order to keep the atmosphere in the semiconductor laser device clean, it is preferable to seal in a dry atmosphere or a nitrogen atmosphere. Further, the temperature at which the semiconductor laser element is sealed with a cap is preferably a dew point of −10 ° C. or lower, more preferably a dew point of −40 ° C. or lower. In addition, each member may be pretreated using a method such as ashing or heat treatment to remove moisture and organic substances attached to each member.

  Further, a holding member or the like may be arbitrarily arranged between the support member and the stem or between the light receiving element and the stem.

The semiconductor laser device according to the present invention is not limited to the one mounted on the metal stem, and can be mounted on various packages. For example, those mounted on ceramics, composite packages using ceramics and metals, and the like can be mentioned. Specifically, materials such as AlN, Al ₂ O ₃ , ZrO ₂ , SiO ₂ , and GaN can be used, and metals such as Cu, Al, Fe, Ni, Mo, CuW, and CuMo can be used as necessary. .

Embodiments of the present invention will be described below with reference to the drawings.
Example 1
In the semiconductor laser device 100 of the present embodiment, as shown in FIG. 6, a cylindrical cap 42 is bonded and hermetically sealed to a stem 40 provided with leads 41. The cap 42 has an opening at the top of the cylindrical shape, and the cap glass 43 is bonded to the opening, and laser light is extracted from the cap glass. In addition, as shown in FIG. 5, the semiconductor laser element 10 is placed on the stem 40 via the light receiving element 20 and the support member 30. As shown in FIG. 3, the semiconductor laser element 10 includes a nitride semiconductor layer 10 c on a substrate 10 b made of a nitride semiconductor, a first electrode 11 a on the back surface of the substrate, and a surface of the nitride semiconductor layer. A second electrode 11b made of Ni / Au / Pt (0.01 μm / 0.1 μm / 0.1 μm) is provided. As shown in FIG. 1, the first electrode 11a is provided so that the back surface of the substrate is partially exposed.
The size of the semiconductor laser element 10 is assumed to be 800 μm in the cavity direction × 200 μm in width × 80 μm in thickness. The size of the light receiving element 20 is assumed that the main body is 500 μm long × 500 μm wide × 200 μm thick, and the light receiving surface 21 is 350 μm long × 350 μm wide. The size of the support member 30 is assumed to be 400 μm in the resonator direction × 500 μm in width × 200 μm in thickness.
The first electrode provided on the back surface of the substrate has an outer periphery exposed by 60 μm from the back surface of the semiconductor laser element having a length of 800 μm in the resonator direction × 200 μm in the cavity direction, and from a position 50 μm from the end surface on the reflective surface side. A notch is provided with a length of 250 μm and a width of 50 μm to form an exposed region.
A light receiving element is arranged on the emission surface side of the laser element through a support member and a 50 μm gap.

As a method for manufacturing such a semiconductor laser device, first, a first electrode is formed on the back surface of the substrate of the semiconductor laser element. An electrode is provided by V / Pt / Au (100 Å / 2000 Å / 3000 Å) and patterned by photolithography and etching to form the electrode having the above-described shape and an exposed region.
Next, a stem is prepared, and a support member made of AlN and a light receiving element made of Si are mounted on the stem using AuSn solder. Thereafter, the semiconductor laser element is mounted on the support member and the light receiving element using AuSn solder.
Subsequently, the semiconductor laser element is mounted, and the laser element and the stem are wired by wire bonding. Thereafter, the cap is joined to the stem and hermetically sealed, whereby the semiconductor laser device can be obtained.

  In the semiconductor laser device thus obtained, electrodes are provided so as to have an exposed region in a region other than directly under the waveguide on the back surface of the substrate, and the light receiving element is arranged so that the exposed region and the light receiving surface of the light receiving element face each other. Therefore, the amount of change in the Im value is small, and the output of the laser beam can be adjusted with high accuracy.

(Example 2)
In the present embodiment, a semiconductor laser device as shown in FIG. 9 bonded to the stem 40 is manufactured as in the first embodiment.
The difference from the first embodiment is that an exposed region is provided in the second electrode provided on the surface of the semiconductor layer of the semiconductor laser element, and the exposed region of the second electrode and the light receiving surface of the light receiving element are opposed to each other. It is a point that has been. Specifically, the outer periphery of the second electrode is exposed to 5 μm, a notch is provided with a length of 50 μm from the end surface on the reflecting surface side, a length of 200 μm, a width of 50 μm, and an exposed region is formed. Is manufactured by junction down mounting. The first electrode is formed without providing a notch. Other than that, it produces similarly to Example 1. FIG.
Compared with the semiconductor laser device of the first embodiment, the semiconductor laser device of the present embodiment can improve the heat dissipation of the laser element.

(Example 3)
In the present embodiment, a semiconductor laser device as shown in FIG. 7 is manufactured by being bonded to the stem 40 as in the first embodiment.
The difference from the first embodiment is the size of the exposed region of the back surface of the semiconductor laser element. The outer surface of the semiconductor laser element having a length of 800 μm × 200 μm in the cavity direction is exposed to 60 μm, and the semiconductor laser is exposed. An exposed region is formed so as to be 75 μm away from the side surface of the element far from the waveguide. The rest is substantially the same as the first embodiment.
In the semiconductor laser device of this embodiment, the same effect as that of Embodiment 1 can be obtained.

Example 4
In the present embodiment, a semiconductor laser device as shown in FIG. 8 bonded to the stem 40 is manufactured as in the first embodiment.
The difference from the first embodiment is that a semiconductor laser element is placed on the light receiving element. Specifically, the size of the light receiving element 20 is such that the main body is 900 μm long × 600 μm wide × 200 μm thick and the light receiving surface 21 is 400 μm long × 400 μm wide. A semiconductor laser element is mounted on the element. Other than that, it produces substantially the same as Example 1.
In the semiconductor laser device of the present embodiment, compared to the first embodiment, the number of mounting of the member can be reduced by the absence of the supporting member, and the deviation at the time of mounting can be reduced. As a result, variation in Im value for each semiconductor laser device can be reduced.

  The semiconductor laser device of the present invention can be used for optical disc applications (optical storage), optical communication systems, printing machines, exposure applications, measurements, and the like. It can also be used as a bio-related excitation light source for detecting the presence or position of a substance.

DESCRIPTION OF SYMBOLS 100 Semiconductor laser device 10 Semiconductor laser element 10a Exposed region 10b Substrate 10c Semiconductor layer 11 Electrode 11a First electrode 11b Second electrode 12 Ridge 13a Outgoing surface 13b Reflecting surface 14 Waveguide region 15 Adhesive layer 16 Notch 17 Insulating film 20 Light reception Element 21 Light-receiving surface 30 Support member 32 Gap 40 Stem 41 Lead 42 Cap 43 Cap glass

Claims (9)

A semiconductor laser device having a first electrode provided on the back surface of the substrate, a semiconductor layer provided on the surface of the substrate, and a second electrode provided on the surface of the semiconductor layer;
In a semiconductor laser device having a light receiving element that receives light output from the semiconductor laser element,
The first electrode is provided so as to partially include an exposed region on the back surface of the substrate, and the light receiving element is disposed such that a light receiving surface faces the exposed region,
The exposed region is a semiconductor laser device formed in a region other than directly under the waveguide. A semiconductor laser device having a first electrode provided on the back surface of the substrate, a semiconductor layer provided on the surface of the substrate, and a second electrode provided on the surface of the semiconductor layer;
In a semiconductor laser device having a light receiving element that receives light output from the semiconductor laser element,
The second electrode is provided to partially include an exposed region on the surface of the semiconductor layer, and the light receiving element is disposed such that a light receiving surface faces the exposed region,
The exposed region is a semiconductor laser device formed in a region other than directly under the waveguide.   The semiconductor laser device according to claim 1, wherein the exposed region is defined by a notch provided in the electrode.   The semiconductor laser device according to claim 1, wherein the exposed region is formed in a central region in a resonator direction.   The said semiconductor laser apparatus has a supporting member in which a semiconductor laser element is mounted, The said laser element is arrange | positioned ranging over the said light receiving element and a supporting member. Semiconductor laser device.   The semiconductor laser device according to claim 5, wherein a gap is provided between the light receiving element and the support member.   7. The semiconductor laser device according to claim 5, wherein a support member is disposed on an emission surface side of the semiconductor laser element, and a light receiving element is disposed on a reflection surface side.   The semiconductor laser device according to any one of 2 to 7, wherein the semiconductor laser element is junction-down mounted.   9. The semiconductor laser device according to claim 2, wherein the exposed region faces the light receiving surface through a light-transmitting insulating film provided on a surface of the semiconductor layer.

Images