JP2018073924A - Manufacturing method of semiconductor laser element, chip-on sub-mount element, and semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress destruction and short life of a laser chip due to pressing load of conduction test, or the like, in the laser chip stage.SOLUTION: A manufacturing method of semiconductor laser element goes through a chip fixing process for fixing a laser chip onto a submount substrate where multiple electrodes, electrically separated from each other, are arranged on the surface, a connection process for electrically connecting both electrodes of the laser chip independently, a pressing process for bringing an energizing pin into contact with each electrode after the connection process, and pressing the submount substrate against a heat slinger by these energizing pins, and an energization process for energizing the laser chip via the energizing pin and each electrode.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a semiconductor laser element, a chip-on-submount element, and a semiconductor laser device.

  2. Description of the Related Art Conventionally, a can type semiconductor laser device in which a submount element (chip-on-submount element) in which a semiconductor chip (laser chip) is mounted on a submount substrate is mounted on a stem, for example, is known. On the other hand, in order to further increase the output, a semiconductor laser device in which a plurality of chip-on-submount elements on which a semiconductor chip is mounted is mounted in the same package has been studied (for example, see Patent Document 1).

JP2013-191787A

However, a semiconductor laser chip continuity test or the like is usually performed after being assembled into a package, and if a chip failure is confirmed at that time, materials and the like are wasted. In particular, when a plurality of chip-on-submount elements are incorporated in the same package, if even one element has an initial failure, the entire package becomes a defective product in the continuity test, resulting in a large waste of materials.
On the other hand, a method of confirming a defect by conducting a continuity test or the like at the laser chip stage (that is, in a state where the laser chips are individually independent) can be considered, but when a pin is pressed on the laser chip for defect confirmation, There is a problem that the laser chip is broken by the load of the above, or damage is applied to shorten the life.
Therefore, an object of the present invention is to suppress laser chip breakage and shortening of service life due to a pressing load such as a continuity test at the laser chip stage.

In order to solve the above problems, one aspect of a method for manufacturing a semiconductor laser device according to the present invention is a chip for fixing a laser chip on a submount substrate on which a plurality of electrodes electrically separated from each other are arranged. A fixing step, a connecting step in which both electrodes of the laser chip are electrically connected to each electrode on the submount substrate independently of each other, an energizing pin is brought into contact with each electrode after the connecting step, and the energizing pins are used to A pressing process of pressing the submount substrate against the heat sink and an energization process of energizing the laser chip through the energization pins and the electrodes are performed.
According to such a method of manufacturing a semiconductor laser device, the continuity test or the like can be performed in a state where the laser chips are individually independent, so that waste of material is suppressed and the energization pin is connected to the submount substrate during the continuity test or the like. Therefore, the laser chip is prevented from being broken or shortened in life.

In the method of manufacturing a semiconductor laser element, a chip-on submount element having the submount substrate and the laser chip and having undergone the energization step is used as one heat sink that absorbs heat generated by light emission of the laser chip. Further, an element fixing step of fixing a plurality may be further performed.
Through such an element fixing step, a high-power semiconductor laser device or the like having a plurality of chip-on-submount elements that have undergone a continuity test or the like can be manufactured. Since the operation of the chip-on-submount element fixed to the heat sink has been confirmed through the energization process, there is little waste of material.

In the method of manufacturing a semiconductor laser element, it is preferable that an inspection step of inspecting characteristics of the laser chip for a single chip-on submount element having the submount substrate and the laser chip is further performed. It is possible to check defective products with high accuracy and to check the characteristics guaranteed as products in the inspection process.
In the method for manufacturing a semiconductor laser device, the energization step may be a step of energizing for burn-in to the laser chip. By burn-in, initial defective products are surely eliminated and only good products are selected.
More specifically, the energization step may be a step of energizing for a longer time than energization for characteristic inspection of the laser chip. Since such energization places a load on the laser chip, defective products are eliminated due to their characteristics being deteriorated, and non-defective products are stabilized.

In order to solve the above problems, an aspect of the chip-on-submount element according to the present invention includes a submount substrate on which a plurality of electrodes electrically separated from each other are arranged on the surface, and the submount substrate. And a laser chip in which both poles are electrically connected to each electrode on the submount substrate independently of each other.
According to such a chip-on-submount element, a continuity test or the like via an electrode arranged on the submount substrate can be performed for each laser chip, so that waste of material is suppressed and a continuity test or the like is performed. Since the pressing of the energizing pin at this time can be performed by the electrode on the submount substrate, the laser chip can be prevented from being broken or shortened.

In the chip-on-submount element, the plurality of electrodes may be electrodes used for burn-in to the laser chip. By burn-in, initial defective products are surely eliminated and only good products are selected.
More specifically, the plurality of electrodes may be electrodes used for energization over a longer period of time than energization for characteristic inspection on the laser chip.
The plurality of electrodes may be arranged side by side in the longitudinal direction of the submount substrate. Since such an electrode arrangement is an electrode arrangement that effectively uses the area on the submount substrate, it contributes to miniaturization of the apparatus.
The plurality of electrodes may be arranged side by side in the length direction of the resonator of the laser chip. Such an electrode arrangement is an arrangement that suppresses the size of the chip-on-submount element in the width direction of the laser chip, and thus contributes to miniaturization of the apparatus.

  In the chip-on-submount element, the laser chip is fixed at a position deviated from the center of the submount substrate, and the plurality of electrodes are arranged on the submount substrate with the laser chip sandwiched therebetween. It may be arranged on the wider side of both sides. Such an arrangement of the laser chip and the electrode is also an arrangement for suppressing the size of the chip-on-submount element in the width direction of the laser chip, which contributes to the miniaturization of the apparatus.

Furthermore, in order to solve the above-described problem, one embodiment of a semiconductor laser device according to the present invention includes a submount substrate on which a plurality of electrodes electrically separated from each other are arranged on a surface, and fixed on the submount substrate. A laser chip in which both electrodes are electrically connected to each electrode on the submount substrate independently of each other, a heat sink that fixes the submount substrate and absorbs heat generated by light emission from the laser chip, and And a heat radiator that dissipates heat absorbed by the heat sink.
According to such a semiconductor laser device, the continuity test and the like through the electrodes arranged on the submount substrate can be performed for each laser chip, so that waste of material is suppressed and the continuity test and the like are performed. Since the current pin can be pressed by the electrode on the submount substrate, the laser chip can be prevented from being broken or shortened.

  According to the present invention, destruction of the laser chip and shortening of the service life due to a pressing load such as a continuity test at the laser chip stage are suppressed.

It is a figure which shows one Embodiment of the semiconductor laser apparatus of this invention. It is a figure which shows a module. It is a figure which shows the structure of a chip on submount element. It is a figure which shows the front | former stage part in one Embodiment of the manufacturing method of the semiconductor laser element of this invention. It is a figure which shows the back | latter stage part in one Embodiment of the manufacturing method of the semiconductor laser element of this invention. It is a figure which shows the chip on submount element used in the 1st modification. It is a figure which shows the chip on submount element used by the 2nd modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of a semiconductor laser device of the present invention.
The semiconductor laser device 1 of the present embodiment is a multi-die package in which, for example, four modules 3 are incorporated in a metal case 2. It is assumed that the upper surface of the metal case 2 is covered with a glass window not shown.
Each module 3 includes a plurality of laser diode (LD) chips as described later, and emits (emits) laser light onto the upper surface of the metal case 2. Thus, a high output device is realized by incorporating a plurality of LD chips in one semiconductor laser device 1.

The metal case 2 has a role of radiating heat generated by each module 3 as it emits light, and corresponds to an example of a radiator according to the present invention. In addition, as a heat radiator as used in the field of this invention, the heat radiating block different from the metal case 2 may be provided, or a heat radiating fin may be provided.
The metal case 2 is also provided with lead pins 4, and power is supplied to each module 3 via the lead pins 4.
A semiconductor laser device 1 shown in FIG. 1 corresponds to an example of a semiconductor laser element to be manufactured by the semiconductor laser element manufacturing method of the present invention. Each module 3 shown in FIG. 1 also corresponds to an example of a semiconductor laser element to be manufactured by the semiconductor laser element manufacturing method of the present invention.

FIG. 2 is a diagram showing the module 3. However, the orientation of the module 3 is different from that in FIG.
The module 3 has a structure in which, for example, six chip-on submount elements 6 are fixed to one heat sink 5 made of copper, for example. Each chip-on-submount element 6 includes one LD chip as will be described later, and emits (emits) laser light in the right direction in FIG. In addition, since the plurality of chip-on submount elements 6 provided in one module 3 form a series circuit, if any one chip-on submount element 6 is defective, the entire module 3 is defective. It becomes a good product.

Each chip-on-submount element 6 provided in the module 3 releases heat accompanying light emission to the heat sink 5. The heat absorbed by the heat sink 5 is dissipated through the metal case 2 shown in FIG.
For the purpose of reducing the size of the device, the distance between the chip-on-submount elements 6 is narrowed to such an extent that an interval necessary for heat absorption by the heat sink 5 remains.
FIG. 3 is a diagram showing the structure of the chip-on submount element 6.
FIG. 3A shows a top view, and FIG. 3B shows a cross-sectional view.

The chip-on submount element 6 is a so-called COS (Chip on Submount), and has a structure in which the LD chip 10 is fixed on the submount substrate 20 with, for example, solder 30. The LD chip 10 corresponds to an example of a laser chip according to the present invention, and the submount substrate 20 corresponds to an example of a submount substrate according to the present invention.
In the example shown in FIG. 3, since the light emitting layer 11 of the LD chip 10 is located on the side close to the submount substrate 20, a part of the laser beam is blocked by the submount substrate 20 (so-called vignetting). For the purpose of avoiding this, the light emitting end 12 of the LD chip 10 protrudes from the end of the submount substrate 20.

  The submount substrate 20 has a structure in which a plurality (two in this example) of electrodes 21 and 22 insulated from each other are disposed on an insulating substrate 23. Here, the insulating substrate 23 has, for example, an insulating material such as aluminum nitride (AlN), silicon carbide (SiC), diamond, etc., or a multi-layer structure having an insulating property in which an insulating material and a conductive material are combined. It may be configured. In the example shown here, both poles of the P side and the N side of the LD chip 10 are located on the upper surface and the lower surface of the LD chip 10, and the lower surface side of the LD chip 10 is on the submount substrate 20 via the solder 30. Connected to one electrode 22. The upper surface side of the LD chip 10 is connected to the other electrode 21 on the submount substrate 20 by so-called wire bonding using a gold wire 40.

Each of the electrodes 21 and 22 on the submount substrate 20 has a current-carrying space that is wide enough to include the pin regions 21a and 22a having a diameter of 0.3 mm at locations sufficiently away from the solder 30, the gold wire 40, and the like. .
In the example shown in FIG. 3, the plurality of electrodes 21 and 22 on the submount substrate 20 are arranged in the longitudinal direction of the submount substrate 20 (vertical direction in FIG. 3A). Since the area of the submount substrate 20 is effectively utilized by this electrode arrangement, the size in the width direction of the chip-on submount element 6 is suppressed while ensuring a sufficient energization space. In recent years, as the output of the semiconductor laser device 1 is increased, the resonator length of the LD chip 10 is increased, and the area of the chip-on-submount element 6 on which the LD chip 10 is mounted is increased. This size reduction greatly contributes to the miniaturization of the semiconductor laser device 1.

In the example shown in FIG. 3, the plurality of electrodes 21 and 22 on the submount substrate 20 are also arranged in the length direction of the resonator of the LD chip 10. By this electrode arrangement, the size of the chip-on-submount element 6 in the width direction of the LD chip 10 is suppressed, which also contributes to the miniaturization of the device.
In the example shown in FIG. 3, the LD chip 10 is arranged at a position deviated from the center of the submount substrate 20, and the plurality of electrodes 21 and 22 are arranged on both sides of the submount substrate 20 with the LD chip 10 interposed therebetween. Of these, they are arranged on the wider side. This electrode arrangement also suppresses the size of the chip-on-submount element 6 in the width direction of the LD chip 10, which also contributes to the miniaturization of the device.

Limiting the size of the chip-on submount element 6 in the width direction of the LD chip 10 is particularly effective when a plurality of chip-on submount elements 6 are incorporated in one case (for example, as shown in FIG. 1). Greatly contributes to the downsizing of products.
The chip-on-submount element 6 shown in FIG. 3 also corresponds to an example of a semiconductor laser element to be manufactured by the method for manufacturing a semiconductor laser element of the present invention.

Next, an embodiment of a method for manufacturing a semiconductor laser device of the present invention will be described.
4 and 5 are diagrams showing an embodiment of a method for manufacturing a semiconductor laser device of the present invention. FIG. 4 shows steps A to D, which are the former part in one embodiment of the manufacturing method, and FIG. 5 shows steps E to G, which are the latter part in one embodiment of the manufacturing method. Has been.
In the present embodiment, first, in step A shown in FIG. 4, the LD chip 10 is fixed on the submount substrate 20 by the solder 30. This step A corresponds to an example of a chip fixing step according to the present invention. Further, in this step A, the lower electrode of the two poles of the LD chip 10 is connected to the electrode 22 on the submount substrate 20 by the solder 30. Therefore, this step A corresponds to a part of the connecting step referred to in the present invention.
Next, in step B shown in FIG. 4, the upper electrode of the two poles of the LD chip 10 is connected to the electrode 21 on the submount substrate 20 by the gold wire 40. This step B corresponds to another part of the connecting step referred to in the present invention. By this step B, the chip-on submount element 6 shown in FIG. 3 is obtained.

Next, in step C shown in FIG. 4, the energization pins 50 are pressed against the pin regions 21 a and 22 a on the submount substrate 20, and the energization pins 50 radiate heat from the submount substrate 20 (chip-on submount element 6). Pressed by the plate 60. Here, the energizing pin 50 is, for example, a probe pin that expands and contracts with a built-in spring, and can be energized while maintaining a constant pressing force. Moreover, the heat sink 60 is a heat sink which consists of aluminum, for example, and has high heat dissipation. This process C corresponds to an example of the pressing process referred to in the present invention.
Next, in step D shown in FIG. 4, power is applied to the LD chip 10 through the electrodes on the submount substrate 20 by applying power to the energization pins 50. This process D corresponds to an example of an energization process according to the present invention.

In step D in the present embodiment, energization for applying a load to the LD chip 10, which is referred to as burn-in, is performed as energization to the LD chip 10.
Specifically, for example, a high current close to the maximum rated current is supplied to the LD chip 10 in a state where the thermostatic chamber is connected to the heat radiating plate 60, and the laser light L is emitted at a high temperature close to the maximum rated temperature, for example. Continuous light emission is performed.
As described above, since a high current flows in the process D, the pressing in the process C needs to be sufficiently strong, but the energizing pin 50 is pressed against the pin regions 21 a and 22 a on the submount substrate 20. Therefore, no force is applied to the LD chip 10 and the destruction and shortening of the life of the LD chip 10 are suppressed. Further, since a sufficient area such as φ0.3 mm is prepared as the pin areas 21a and 22a, a high current can be supplied.
The energization in the burn-in is, for example, a long-time energization for about one day. As a result of such a long-time energization, carriers in the LD chip 10 are activated and the characteristics of the LD chip 10 are improved. Stabilize.

  Conversely, when a crystal defect has occurred in the LD chip 10 (that is, a defective product), the crystal deteriorates due to a load caused by energization with a high current over a long period of time, resulting in a clear characteristic deterioration. Defective products are sorted out and eliminated. For this reason, since only the good chip-on-submount element 6 is incorporated in the semiconductor laser device 1, the reliability of the product is improved and the loss of members is reduced, which is excellent in terms of cost.

  In the manufacturing method of the present embodiment, after the process D shown in FIG. 4, the process proceeds to the process E shown in FIG. 5, and the current-carrying pins 70 for characteristic inspection are again pressed against the pin regions 21 a and 22 a. 6 is attached to a heat radiating plate 80 for characteristic inspection. The heat radiating plate 80 for characteristic inspection has a heat radiating capability comparable to that of the metal case 2 of the semiconductor laser device 1 shown in FIG. 1 and is not connected to a thermostatic chamber or the like. There is enough space for inspection.

  In step F shown in FIG. 5, energization for inspecting the characteristics of the chip-on-submount element 6 (LD chip 10) is performed via the energization pins 70. This process F corresponds to an example of an inspection process according to the present invention. The characteristics to be inspected here include, for example, the oscillation threshold of the laser beam L, the oscillation wavelength, the optical output value for a specific input power, the amount of change in the optical output value with respect to the input power change, the input current value and the input voltage. For example, the curve corresponding to the value. When these characteristics are inspected, it is assumed that energization is performed for a short time with a current low enough that the characteristics do not change during measurement. For example, energization by pulse operation. In other words, in the burn-in described above, it can be said that energization is performed for a longer time than the energization for the characteristic inspection, and it can be said that energization with a higher current is performed than the energization for the characteristic inspection. For example, energization by continuous operation (CW operation). Such characteristic inspection provides a guaranteed value as a product, and also reliably rejects defective products with little characteristic deterioration that were not excluded in step D shown in FIG. The property is further improved.

In the present embodiment, the process F is executed after the process D due to space or the like, but the inspection process referred to in the present invention may be a process executed simultaneously with the energization process referred to in the present invention. .
In step G shown in FIG. 5, a plurality of (for example, six) chip-on submount elements 6 are fixed to one heat sink 5 to form the module 3 shown in FIG. This process G corresponds to an example of an element fixing process according to the present invention. By the process G after the process D and the like, the highly reliable module 3 that does not include the defective chip-on-submount element 6 is obtained.
In the present embodiment, after the process G shown in FIG. 5, the module 3 is assembled in the metal case 2 shown in FIG. 1, and the process of completing the semiconductor laser device 1 by executing the wiring and the glass window is executed. The illustration is omitted.

Next, a modification of the above-described embodiment will be described.
The first modification example is the same as the above-described embodiment except that a chip-on submount element 100 described below is used instead of the chip-on submount element 6 shown in FIG.
FIG. 6 is a diagram showing a chip-on-submount element 100 used in the first modification.
6A shows a top view, and FIG. 6B shows a cross-sectional view.
The chip-on submount element 100 in the first modified example has a structure in which the LD chip 10 is fixed on the submount substrate 110, similarly to the chip-on submount element 6 shown in FIG. The upper electrodes 111 and 112 are arranged in a state of being retracted from the edge of the insulating substrate 23. As described above, the electrodes 111 and 112 are retracted from the edge of the insulating substrate 23, so that the electrodes 111 and 112 are surely connected to the heat sinks 60 and 80 in the process D of FIG. 4 and the process F of FIG. Insulated.

Next, a second modification will be described.
FIG. 7 is a diagram showing a chip-on-submount element 200 used in the second modification.
FIG. 7A shows a top view and FIG. 7B shows a cross-sectional view.
The chip-on-submount element 200 in the second modification includes a low-power LD chip 210, and the resonator length of the LD chip 210 is short. The chip-on submount element 200 also has a structure in which an LD chip 210 is fixed on a submount substrate 220.

  The submount substrate 220 includes a plurality of electrodes 221 and 222 that are insulated from each other. The electrodes 221 and 222 are arranged in the longitudinal direction of the submount substrate 220. However, it is arranged in the width direction rather than the length direction of the resonator of the LD chip 210. When the resonator length of the LD chip 210 is short, the area on the submount substrate 220 is effectively utilized by such an electrode arrangement, which contributes to downsizing of the device. Also in the case of the second modification, it is assumed that pin regions 221a and 222a of φ0.3 mm corresponding to burn-in due to a high current are secured to the electrodes 221 and 222, respectively.

Further, in the second modification, it is not intended to increase the output of the apparatus, and a so-called can-type semiconductor laser element in which only one chip-on submount element 200 shown in FIG. 7 is incorporated is formed. And
The chip-on-submount element 200 shown in FIG. 7 is also manufactured by the manufacturing method shown in FIGS. 4 and 5 (except for step G). For this reason, the destruction and shortening of the life of the LD chip 210 due to the pressing of the energizing pins during burn-in are suppressed.

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser apparatus, 3 ... Module, 5 ... Heat sink, 6, 100, 200 ... Chip on submount element 10, 210 ... LD chip, 20, 110, 220 ... Submount substrate, 21, 22, 111, 112 , 221, 222 ... electrode, 50, 70 ... energizing pin, 60, 80 ... heat sink

Claims (12)

A chip fixing step of fixing a laser chip on a submount substrate on which a plurality of electrodes electrically separated from each other are arranged;
A connecting step of connecting both electrodes of the laser chip to each electrode on the submount substrate electrically independently from each other;
After the connecting step, an energizing pin is brought into contact with each of the electrodes, and a pressing step of pressing the submount substrate against the heat sink by the energizing pin;
An energization step of energizing the laser chip via the energization pins and the electrodes;
A method for manufacturing a semiconductor laser device, wherein:   An element fixing step of fixing a plurality of chip-on-submount elements having the submount substrate and the laser chip to the heat sink that absorbs the heat generated by the laser chip when the laser chip emits light. The method of manufacturing a semiconductor laser device according to claim 1, further comprising:   3. The semiconductor laser device manufacturing method according to claim 1, further comprising an inspection step of inspecting characteristics of the laser chip for a single chip-on-submount device having the submount substrate and the laser chip. Method.   4. The method of manufacturing a semiconductor laser device according to claim 1, wherein the energizing step is a step of energizing for burn-in to the laser chip.   5. The semiconductor laser device manufacturing according to claim 1, wherein the energization step is a step of energizing for a longer time than energization for characteristic inspection of the laser chip. Method. A submount substrate having a plurality of electrodes electrically separated from each other disposed on the surface;
A laser chip fixed on the submount substrate and having both electrodes electrically and independently connected to each electrode on the submount substrate;
A chip-on-submount element comprising:   7. The chip-on-submount element according to claim 6, wherein the plurality of electrodes are electrodes used for burn-in with respect to the laser chip.   8. The chip-on-submount element according to claim 6, wherein the plurality of electrodes are electrodes that are used for energization for a longer time than for energization for characteristic inspection of the laser chip.   9. The chip-on-submount element according to claim 6, wherein the plurality of electrodes are arranged side by side in the longitudinal direction of the submount substrate.   10. The chip-on-submount element according to claim 6, wherein the plurality of electrodes are arranged side by side in a length direction of a resonator of the laser chip. 11. The laser chip is fixed at a position offset from the center of the submount substrate,
11. The device according to claim 6, wherein the plurality of electrodes are arranged on a wider side of both sides of the submount substrate sandwiching the laser chip. 11. Chip-on-submount element. A submount substrate having a plurality of electrodes electrically separated from each other disposed on the surface;
A laser chip fixed on the submount substrate and having both electrodes electrically and independently connected to each electrode on the submount substrate;
A heat sink that fixes the submount substrate and absorbs heat generated by the laser chip as it emits light;
A radiator that dissipates heat absorbed by the heat sink;
A semiconductor laser device comprising:

Images