JP5659876B2 - Manufacturing method of semiconductor laser driving device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor laser driving device including a protection element.

  In general, there is a semiconductor laser device including a protective element in a package in order to protect a laser diode from a surge current (for example, Patent Document 1). Further, when the semiconductor laser device is used for writing on an optical disk, high-speed response may be required to drive the pulse.

Japanese Patent Laid-Open No. 05-102605

By providing the protective element in the semiconductor laser device, it is possible to prevent the semiconductor laser element from being broken by a surge current. However, the semiconductor laser device provided with the protection element has a problem that the response characteristic of the semiconductor laser element deteriorates because the capacitance increases.
Accordingly, an object of the present application is to provide a method of manufacturing a semiconductor laser driving device that achieves both protection from surge current of the semiconductor laser element and high response characteristics.

  A method of manufacturing a semiconductor laser driving device according to an embodiment includes a step of electrically connecting a semiconductor laser device including a semiconductor laser element and a protection element to a laser driving circuit, and protection element insulation for electrically insulating the protection element. Steps.

  According to the manufacturing method of the semiconductor laser driving device of the present application, it is possible to achieve both protection from surge current and high response characteristics of the semiconductor laser element.

It is a schematic perspective view for demonstrating the structure of the semiconductor laser apparatus of embodiment. It is a circuit diagram for demonstrating the manufacturing method of the semiconductor laser drive device of embodiment. It is a schematic plan view for demonstrating the structure of the semiconductor laser apparatus of another embodiment. It is a schematic plan view of the principal part for demonstrating the structure of the semiconductor laser apparatus of another embodiment. It is a schematic plan view of the principal part for demonstrating the structure of the semiconductor laser apparatus of another embodiment.

  Embodiments will be described below with reference to the drawings. However, the form shown below illustrates the manufacturing method of the semiconductor laser drive device for actualizing the technical idea of this invention, Comprising: This invention is not limited to the following. In addition, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention only to the mere illustration unless otherwise specified. Only. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation.

(Embodiment 1)
FIG. 1 is a perspective view of the semiconductor laser device of the embodiment.
In the semiconductor laser device 1 of the embodiment, the semiconductor laser element 3 is arranged on the stem heat sink 2b via the submount 6. The semiconductor laser element 3 emits laser light upward. A protective element 4 is arranged behind the semiconductor laser element and on the base portion 2a of the stem. Leads (21, 22, 23) are provided so as to penetrate the base portion 2a of the stem. The semiconductor laser element 3 is electrically connected to the first lead 21 and the second lead 22 by wires 5a and 5b, and the protective element 4 is electrically connected by wires 5c and 5d. Further, although partially illustrated for convenience of explanation, the semiconductor laser device is sealed with a cap 7 so as to cover the semiconductor laser element 3 and the protection element 4.

A method for manufacturing the semiconductor laser driving device of this embodiment will be described. First, a process for assembling a semiconductor laser device.
First, the semiconductor laser element 3 is mounted on the stem. The semiconductor laser device can be mounted by aligning the bonding surfaces of the semiconductor laser device and the stem and then holding them under a predetermined temperature and pressure. Specifically, the thermocompression bonding method, the direct bonding method, etc. Is mentioned. As a bonding material between the semiconductor laser element and the stem, 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.), an Ag-based bonding material, a bonding resin Can be used.

  The semiconductor laser element may have any structure such as face-down mounting in which the semiconductor layer side of the semiconductor laser element is mounted on the stem, and face-up mounting in which the substrate side of the semiconductor laser element is mounted on the stem.

  In the semiconductor laser element 3, when a voltage is applied and a current exceeding a threshold value flows, laser oscillation occurs in the active layer and its vicinity, and the generated laser light is emitted to the outside through the waveguide region. It is. Further, the semiconductor material is a compound using a compound such as III-V group or II-VI group, and may emit laser light of any wavelength. For example, a semiconductor laser element made of a nitride semiconductor such as GaN can be used. As a structure of the semiconductor laser element, for example, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are sequentially stacked on a conductive or insulating substrate, and an insulating film or an electrode is formed on the surface of the semiconductor layer. Is mentioned. Further, the semiconductor laser device may have one or a plurality of semiconductor laser elements.

  Since the stem is also used to efficiently release the heat generated in the semiconductor laser element to the outside, the stem may be formed of a material having a relatively high thermal conductivity, for example, a material of about 20 W / mK or more. preferable. Specific materials include metals such as Cu, Al, Fe, Ni, Mo, CuW, and CuMo, and ceramics such as AlN, SiC, and alumina. Conductivity may be ensured by using these metals or ceramics as a base material and plating the whole or part of the surface 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. As the planar shape, a circular shape, an elliptical shape, a polygonal shape such as a rectangle, or a shape similar to these can be used. For example, a circular and flat plate having a diameter of about 3 to 10 mm can be used. The thickness is preferably about 0.5 to 5 mm. Further, the stem is not limited to a flat plate shape, and a concave portion and / or a convex portion may be provided on the surface thereof. For example, the thing in which the recessed part or the convex part is provided in the area | region in which a semiconductor laser element and / or a protection element are mounted is mentioned. Specifically, as shown in FIG. 1, a shape in which a convex heat sink 2b for mounting a semiconductor laser element is provided on a substantially circular and flat base portion 2a can be mentioned.
The stem may be provided with a lead for connecting to an external power source. Examples of the lead include those formed of the same material as the stem and bonded with low-melting glass so as to penetrate the stem. Moreover, you may have a wiring pattern in the surface or inside of a stem.

  Next, the protection element 4 is mounted on the stem. The protection element can be mounted by the same method as the mounting of the semiconductor laser element. After the bonding surfaces of the protective element and the stem are brought together, they can be bonded by being held under a predetermined temperature and pressure. As a bonding material for the protective element and the stem, 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.), an Ag-based bonding material, and a bonding resin are used. Can be used.

  The position where the protective element is mounted is not limited to the base portion of the stem. For example, it may be arranged on the heat sink of the stem as in the semiconductor laser element. Although details will be described later, the protection element may be mounted on the stem via a submount. When the semiconductor laser element is mounted on the stem via the submount, the protective element may be disposed on the same submount or on a different submount.

  The protection element is a member for protecting the semiconductor laser element from electrical breakdown due to a surge current. The protective element is connected in parallel to the semiconductor laser element in the opposite direction. When a voltage is applied to the semiconductor laser element in the reverse direction or when an excessive voltage is applied in the forward direction, a current flows through the protective element and the semiconductor laser element. By preventing current from flowing through the laser element, it is possible to prevent the semiconductor laser device from failing. For example, a Zener diode made of Si can be used as the protective element.

Next, a semiconductor laser device is obtained by connecting the semiconductor laser element, the protection element, and the leads with wires.
In the semiconductor laser device of the embodiment, the anode side of the semiconductor laser element is connected to the first lead 21 by the wire 5a, and the cathode side is connected to the second lead 22 by the wire 5b. The anode side of the protective element is connected to the second lead 22 by a wire 5c, and the cathode side is connected to the first lead 21 by a wire 5d.
As the wire, a commonly used material can be used. Specifically, a material such as Au, Ag, or Cu having a diameter of about 10 to 50 μm can be used. The length can be appropriately set according to the distance between the members to be connected. Moreover, it is not limited to connecting by one between the members to connect, You may connect using two or more.

Hereinafter, other steps will be described.
The semiconductor laser element and the protection element may be mounted on the stem via a submount. When a submount is used, the semiconductor laser element is mounted on the submount and bonded, and then the submount is bonded to the stem. The submount is mounted and bonded on the stem, and then the semiconductor laser element is mounted. And a method of adhering to the submount. The mounting of the semiconductor laser element on the submount and the mounting of the submount on the stem can be performed in the same manner as the mounting of the semiconductor laser element on the stem. The same can be said for the protective element. In addition, a stem and a submount, which are members for mounting the semiconductor laser element and / or the protection element, may be collectively referred to as a “support”.

  For the submount, a member having high thermal conductivity is preferably used for heat dissipation, and specific examples include AlN, CuW, diamond, SiC, ceramics, and the like. It is preferable that a thin film of metal such as Ti / Pt / Au or Ni / Au is formed on the surface to ensure conductivity.

  In the semiconductor laser device 1 of this embodiment, the cap 7 may be attached to the stem and sealed so as to cover the semiconductor laser element 3 and the protection element 4. When a semiconductor laser element using a semiconductor material with a short wavelength of about 320 to 530 nm (for example, a nitride semiconductor) is used, it is easy to collect organic matter and moisture. This is preferable because it can improve the airtightness and improve the waterproofness and dustproofness.

  When the semiconductor laser device is sealed with a cap, it can be adhered to the stem by resistance welding or soldering. When sealing, it is preferable to seal in dry air or nitrogen atmosphere having a dew point of −10 ° 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.

Examples of the shape of the cap include a bottomed cylindrical shape (such as a cylinder or a polygonal column), a truncated cone shape (such as a truncated cone or a polygonal truncated cone), a dome shape, and a deformed shape thereof. The cap is preferably formed of a material having high thermal conductivity. For example, a material such as Ni, Co, Fe, Ni—Fe alloy, Kovar, or brass can be used.
A portion corresponding to the laser light emission part on the upper surface or side surface of the cap has an opening through which the laser light passes. Specifically, as shown in FIG. 1, a cap having an opening at the top of the cap bonded to the stem, and a transparent member for extracting laser light being supported in the opening, should be used. Can do. The translucent member can be formed of, for example, glass, sapphire, ceramics, resin, or the like. 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.

  Further, a photodiode may be arranged at a desired position in order to monitor the output of the semiconductor laser element.

Subsequently, as shown in FIG. 2A, in order to supply current to the obtained semiconductor laser device, it is connected to a laser driving circuit.
When the protection element is electrically connected in the semiconductor laser device, the capacitance increases, so that the response characteristics are poor as compared with the semiconductor laser device not provided with the protection element. However, by electrically insulating the protection element in the subsequent steps, no current flows through the protection element even when a current is passed through the semiconductor laser element, so that the responsiveness during circuit driving can be improved. .
Further, it is preferable that a surge protection circuit is incorporated in the laser drive circuit so that a current or voltage exceeding a certain level does not flow. The laser drive circuit may cause a surge current to flow due to friction, charging of surrounding devices and jigs, static electricity derived from the handling human body, etc. Therefore, it is possible to prevent the semiconductor laser element from being broken. A known circuit can be used as the surge protection circuit. For example, a method of separately providing a circuit for bypassing the surge current can be used.
Since the semiconductor laser element incorporated in the laser driving circuit having such a surge protection circuit is protected by the surge protection circuit, the protection element in the semiconductor laser device is not necessary.
That is, according to the manufacturing method of the embodiment, the semiconductor laser device can be protected from the surge current by the protective element provided in the semiconductor laser device until the semiconductor laser device is incorporated in the laser drive circuit. After the semiconductor laser device is incorporated in the laser drive circuit and the protective element is insulated, the protective element in the semiconductor laser device is electrically insulated, so that the response characteristic is the same as that of the semiconductor laser device that does not include the protective element. Therefore, it is possible to manufacture a semiconductor laser driving device that achieves both protection from surge current and maintenance of response characteristics. Further, by providing the laser drive circuit with a surge protection circuit, the semiconductor laser device can be protected from surge current even after the semiconductor laser device is incorporated in the laser drive circuit and the protection element is insulated.

  Finally, the protective element is insulated to obtain a semiconductor laser driving device having a circuit diagram as shown in FIG. The protection element can be insulated from the laser drive circuit by cutting the wire in the semiconductor laser device connecting the protection element and the laser drive circuit. In order to cut the wire connecting the protective element and the laser driving circuit, it is sufficient to apply a current. In the present embodiment, of the two wires (wire 5c and wire 5d) connected to the protection element, this wire is cut when heat is generated at a portion having the highest resistance in the current path. (Hereinafter, the wire to be cut is referred to as a first wire, and the wire that is connected to the protective element and is not cut is referred to as a second wire). When the materials of the first wire and the second wire are the same, the current value at which the wire is cut is determined by the diameter and length of the first wire. For example, when the first wire made of Au and having a diameter of 20 μm is used, the wire can be cut by applying a current of about 700 mA. In this step, deterioration of the semiconductor laser element can be suppressed by applying a voltage lower than the reverse breakdown voltage of the semiconductor laser element.

Specifically, in the semiconductor laser device connected as shown in FIG. 1, when the material and the diameter of the wire 5c and the wire 5d are the same, the longer wire 5d is cut.
That is, when the protective element is connected to the laser driving circuit by the first wire (5d) and the second wire (5c), and the diameters of the first wire (5d) and the second wire (5c) are the same. The first wire is cut by making the first wire longer than the second wire.
Further, when the materials and diameters of the first wire (5d) and the second wire (5c) are the same, the first wire (5d) is cut by providing a plurality of second wires (5c). can do.
Alternatively, when the material and length of the first wire (5d) and the second wire (5c) are the same, the first wire (5d) is smaller in diameter than the second wire (5c). By using it, the first wire (5d) can be cut.

(Embodiment 2)
A plan view of the semiconductor laser device of Embodiment 2 is shown in FIG. 3A. FIG. 3B is an enlarged plan view of the submount. In the present embodiment, the semiconductor laser element 3 and the protection element 4 are disposed on the same submount 6.
In the semiconductor laser device of this embodiment, the anode side of the semiconductor laser element is connected to the first lead 21 by the wire 5e, and the cathode side is connected to the second lead 22 by the wire 5f. The anode side of the protection element is connected to the second lead 22 by the same wire 5f as the semiconductor laser element, and the cathode side is connected to the first lead 21 by the wire 5g.

  Also in this embodiment, the semiconductor laser device and the laser drive circuit are electrically connected in the same manner as in the first embodiment, and then the protective element is insulated by cutting the wire connected to the protective element. It is possible to achieve both protection from surge current and suppression of deterioration of response characteristics. In the present embodiment, of the two wires (the wire 5f and the wire 5g) that connect the protection element and the laser drive circuit, the wire 5f serves to electrically connect the semiconductor laser element to the laser drive circuit. The protective element is insulated by cutting the wire 5g. That is, the wire 5g directly connected to the protection element may be cut.

  Specifically, in order to cut the wire 5g, when wires of the same material and diameter are used for the wire 5f and the wire 5g, the wire 5g can be cut by making the wire 5g longer than the wire 5f. . Alternatively, the wire 5g can be similarly cut even if the number of wires connecting the lead 22 and the submount illustrated by the wire 5f is increased. When wires having different diameters are used, the wire 5g can be cut by making the diameter of the wire 5f larger than the diameter of the wire 5g.

When such a semiconductor laser device is used, the member to be mounted on the stem is only one submount as compared with the first embodiment, so that the process can be simplified and the yield can be improved. Furthermore, since the wire on the cathode side of the semiconductor laser element and the wire on the anode side of the protective element can be used together, the process can be reduced even if the number of wires used is reduced.
In addition, the present embodiment is not limited to using a semiconductor laser device using a submount, and can have the same form on a support.

(Embodiment 3)
FIG. 4 shows an enlarged plan view of the submount of the semiconductor laser device according to the third embodiment. In the present embodiment, the semiconductor laser element 3 and the protection element 4 are arranged on the same submount 6 as in the second embodiment, and are connected to leads (not shown) by wires (5e, 5f, 5g). .

The submount 6 has conductivity on the surface thereof. The present embodiment is different from the second embodiment in that insulating portions Y1 and Y2 are partially formed on the surface of the submount. For example, as shown in FIG. 4, insulating portions Y1 and Y2 are provided, and a conductive portion X in which a current path is narrowed by being sandwiched between the insulating portions Y1 and Y2 is provided.
When a current is applied to the semiconductor laser device, a current flows through a path of the wire 5f, the protection element 4, and the wire 5g. It is formed between.
As a method of manufacturing such a submount, a conductive portion may be formed on the surface by providing a mask having a desired insulating portion shape on the base material of the submount and providing a metal thin film as described above.

  In the present embodiment, after electrically connecting the semiconductor laser device and the laser driving circuit in the same manner as in the other embodiments, the protective element is insulated by breaking the conductive portion X passing between the insulating portions Y1 and Y2. Thus, it is possible to achieve both protection from the surge current of the semiconductor laser element and suppression of deterioration in response characteristics.

  As in the other embodiments, heat is generated at a location with the highest resistance in the current path, whereby the conductive portion can be cut and the protection element can be insulated. In order to break the conductive part X, the width and length of the conductive part may be adjusted. Specifically, the conductive portion X can be broken by setting the width of the conductive portion X to about 10 to 100 μm and the length to about 30 to 300 μm. For example, when the material of the conductive part is Ti / Pt / Au (thickness is 0.1 μm / 0.2 μm / 0.6 μm), the width of the conductive part is 50 μm, and the length is 120 μm, the current is about 500 mA. The conductive portion can be cut by applying a current. At this time, it is preferable that a current of 600 mA or more can be applied to the wire 5g. Specifically, the wire may have a diameter of 20 μm or more and a length of 1000 μm or less.

When such a semiconductor laser device is used, it becomes possible to insulate the protective element at a desired position, and it is easy to confirm whether or not the protective element is insulated reliably. In detail, when breaking a wire, the wire is usually about the same thickness over its entire length, so identifying where in the first wire it will break before the protective element insulation process is Have difficulty. However, in the present embodiment, the fracture position can be specified to some extent by forming a conductive pattern by providing a desired pattern on the submount. Furthermore, since the conductive portion provided on the submount is broken, there is little scattering at the time of breakage, and contamination in the semiconductor laser device can be suppressed.
Further, the present embodiment is not limited to using a semiconductor laser device using a submount, and the same form can be used on a support.

  The manufacturing method of the semiconductor laser driving device of the present invention can be used for manufacturing all devices such as an optical disk, an optical communication system, a projector, a display, a printing machine, or a measuring instrument.

1: Semiconductor laser device 2a: Stem (base part)
2b: Stem (heat sink)
21, 22, 23: Lead 3: Semiconductor laser element 4: Protection elements 5a, 5b, 5c, 5d, 5e, 5f, 5g: Wire 6: Submount 7: Cap X: Conductive part Y1, Y2: Insulating part

Claims (7)

Electrically connecting a semiconductor laser device comprising a semiconductor laser element and a Zener diode to a laser driving circuit;
A method of manufacturing a semiconductor laser driving device comprising a Zener diode insulating step for electrically insulating the Zener diode,
The Zener diode is electrically connected to the laser drive circuit by a first wire and a second wire having the same diameter as the first wire and a shorter length than the first wire. And
A method of manufacturing a semiconductor laser driving device, wherein, in the Zener diode insulating step, the first wire is cut by applying a current to electrically insulate the Zener diode. Electrically connecting a semiconductor laser device comprising a semiconductor laser element and a Zener diode to a laser driving circuit;
A method of manufacturing a semiconductor laser driving device comprising a Zener diode insulating step for electrically insulating the Zener diode,
The Zener diode is electrically connected to the laser driving circuit by a first wire and a plurality of second wires having the same diameter as the first wire,
A method of manufacturing a semiconductor laser driving device, wherein, in the Zener diode insulating step, the first wire is cut by applying a current to electrically insulate the Zener diode. Electrically connecting a semiconductor laser device comprising a semiconductor laser element and a Zener diode to a laser driving circuit;
A method of manufacturing a semiconductor laser driving device comprising a Zener diode insulating step for electrically insulating the Zener diode,
The Zener diode is electrically connected to the laser driving circuit by a first wire and a second wire having the same length as the first wire and having a diameter larger than that of the first wire. And
A method of manufacturing a semiconductor laser driving device, wherein, in the Zener diode insulating step, the first wire is cut by applying a current to electrically insulate the Zener diode.   4. The method of manufacturing a semiconductor laser driving device according to claim 1, wherein the laser driving circuit includes a surge protection circuit. 5.   5. The method of manufacturing a semiconductor laser driving device according to claim 1, wherein the semiconductor laser element and the Zener diode are provided on the same submount. 6.   6. The method of manufacturing a semiconductor laser driving device according to claim 1, wherein the first wire is directly connected to the Zener diode. Electrically connecting a semiconductor laser device comprising a semiconductor laser element and a Zener diode to a laser driving circuit;
And a Zener diode insulating step for electrically insulating the Zener diode in order,
The Zener diode is mounted on a support having a conductive portion on the surface, and is electrically connected to the laser driving circuit by the conductive portion,
A method of manufacturing a semiconductor laser driving device, wherein, in the Zener diode insulating step, the conductive portion is cut by applying a current to electrically insulate the Zener diode.