JP6980996B2 - Manufacturing method of semiconductor laser element, chip-on-submount element, and semiconductor laser element - Google Patents

Description

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

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 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 is also being studied (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-191787

However, the continuity test of the semiconductor laser chip or the like is usually executed after being assembled in the package, and if a defect of the chip is confirmed at that time, the material or the like is wasted. In particular, when a plurality of chip-on-submount elements are incorporated in the same package, if even one element has an initial defect, the entire package becomes a defective product in the continuity test, and the waste of materials and the like is large.
On the other hand, a method of confirming a defect by performing 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. There is a problem that the laser chip is destroyed by the load of the laser chip, or the life is shortened due to damage.
Therefore, it is an object of the present invention to suppress the destruction and shortening of the life of the laser chip due to the pressing load such as the continuity test at the laser chip stage.

In order to solve the above problems, one aspect of the method for manufacturing a semiconductor laser element according to the present invention is a chip in which a laser chip is fixed on a submount substrate in which a plurality of electrodes electrically separated from each other are arranged on the surface. The fixing step, the connection step of electrically connecting the two electrodes of the laser chip to each electrode on the submount substrate electrically independently, and the connection step, after the connection step, the current-carrying pins are brought into contact with the respective electrodes, and the current-carrying pins are used. A pressing step of pressing the submount substrate against the heat radiating plate and an energizing step of energizing the laser chip via the energizing pin and each of the electrodes are performed.
According to such a method for manufacturing a semiconductor laser device, it is possible to perform a continuity test or the like in a state where the laser chips are individually independent, so that waste of materials is suppressed and the energizing pin is placed on the submount substrate during the continuity test or the like. Since it is pressed against the electrode of the laser chip, the destruction of the laser chip and the shortening of the service life are suppressed.

In the method for manufacturing a semiconductor laser device, a chip-on-submount element having the submount substrate and the laser chip and undergoing the energization step is one heat sink that absorbs heat generated by the laser chip due to light emission. A plurality of element fixing steps for fixing a plurality of elements may be further performed.
By going through such an element fixing step, it is possible to manufacture a high-power semiconductor laser device or the like equipped with a plurality of chip-on-submount elements that have been subjected to a continuity test or the like. 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.

Further, in the method for manufacturing a semiconductor laser device, it is preferable to further go through an inspection step of inspecting the characteristics of the laser chip for a single chip-on-submount element having the submount substrate and the laser chip. It is possible to check defective products with high accuracy and check the characteristics guaranteed as a product in the inspection process.
Further, 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. Burn-in ensures that initial defective products are eliminated and only good products are selected.
More specifically, the energization step may be a step of energizing for a longer time than the energization for the characteristic inspection of the laser chip. Since such energization imposes a load on the laser chip, defective products deteriorate in characteristics and are eliminated, and good products stabilize their characteristics.

Further, in order to solve the above problems, one aspect of the chip-on-submount element according to the present invention is a submount substrate on which a plurality of electrodes electrically separated from each other are arranged on the surface and the submount substrate. It comprises a laser chip, fixed to and in which both electrodes are electrically connected to each electrode on its submount substrate, electrically independently of each other.
With 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 materials can be suppressed and a continuity test or the like can be performed. Since the pressing of the energizing pin at this time can be performed by the electrode on the submount substrate, the destruction of the laser chip and the shortening of the life are suppressed.

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

Further, 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 of the submount substrate sandwiching the laser chip. It may be arranged on the wider side of both sides. Such an arrangement of the laser chip and the electrode also contributes to the miniaturization of the apparatus because it is an arrangement that suppresses the size of the chip-on-submount element in the width direction of the laser chip.

Further, in order to solve the above problems, one aspect of the semiconductor laser apparatus according to the present invention is a submount substrate in which a plurality of electrically separated electrodes are arranged on the surface and fixed on the submount substrate. A laser chip in which both poles are electrically and independently connected to each electrode on the submount substrate, a heat sink in which the submount substrate is fixed and the laser chip absorbs heat generated by light emission, and the above. It includes a radiator that dissipates heat absorbed by the heat sink.
According to such a semiconductor laser device, a continuity test or the like via an electrode arranged on a submount substrate can be performed for each laser chip, so that waste of materials can be suppressed and a continuity test or the like can be performed. Since the energizing pin can be pressed by the electrode on the submount substrate, the destruction of the laser chip and the shortening of the life are suppressed.

According to the present invention, the destruction and shortening of the life of the laser chip due to the pressing load such as the 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 pre-stage part in one Embodiment of the manufacturing method of the semiconductor laser element of this invention. It is a figure which shows the latter part 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 in 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 the 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 (lights) laser light to the upper surface of the metal case 2. As described above, 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 when it emits light, and corresponds to an example of a heat radiating body according to the present invention. The heat radiating body according to the present invention may be provided with a heat radiating block different from the metal case 2, or may be provided with heat radiating fins.
The metal case 2 is also provided with a lead pin 4, and power is supplied to each module 3 via the lead pin 4.
The semiconductor laser device 1 shown in FIG. 1 corresponds to an example of a semiconductor laser device to be manufactured by the method for manufacturing a semiconductor laser device of the present invention. Further, each module 3 shown in FIG. 1 also corresponds to an example of a semiconductor laser device to be manufactured by the method for manufacturing a semiconductor laser device 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 described later, and emits (lights) laser light to the right in FIG. Further, since the plurality of chip-on-submount elements 6 provided in one module 3 form a series circuit, if any one of the chip-on-submount elements 6 is a defective product, the entire module 3 cannot be used. It will be a good product.

Each chip-on-submount element 6 provided in the module 3 dissipates heat associated with 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 downsizing the apparatus, the mutual spacing between the chip-on-submount elements 6 is narrowed to such an extent that the spacing required 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. 3 (A) shows a top view, and FIG. 3 (B) shows a sectional view.

The chip-on-submount element 6 is a so-called COS (Chip on Submount), and has a structure in which an LD chip 10 is fixed on a submount substrate 20 by, 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 luminous flux of the laser beam is blocked by the submount substrate 20 (so-called vignetting). The light emitting end 12 of the LD chip 10 is projected from the end of the submount substrate 20 for the purpose of avoiding the above.

The submount substrate 20 has a structure in which a plurality of (two in this example) electrodes 21 and 22 isolated from each other are arranged on an insulating substrate 23. Here, the insulating substrate 23 has an insulating material such as aluminum nitride (AlN), silicon carbide (SiC), and diamond, as well as a multi-layer structure having an insulating property by combining an insulating material and a conductive material. It may be configured. Both 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 in the example shown here, and the lower surface side of the LD chip 10 is on the submount substrate 20 via the solder 30. It is connected to one of the electrodes 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 with a gold wire 40.

Each of the electrodes 21 and 22 on the submount substrate 20 has a widened energization space including the pin regions 21a and 22a having a diameter of 0.3 mm at a position sufficiently distant from the solder 30 and the gold wire 40. ..
Further, in the example shown in FIG. 3, the plurality of electrodes 21 and 22 on the submount substrate 20 are arranged side by side 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 of the chip-on-submount element 6 in the width direction is suppressed while ensuring a sufficient energization space. In recent years, with the increase in output of the semiconductor laser device 1, the resonator length of the LD chip 10 has become longer, and the area of the chip-on-submount element 6 on which the LD chip 10 is mounted has also increased. The size suppression of the semiconductor laser device 1 greatly contributes to the miniaturization of the semiconductor laser device 1.

Further, in the example shown in FIG. 3, the plurality of electrodes 21 and 22 on the submount substrate 20 are arranged so as to be arranged in the length direction of the resonator of the LD chip 10. Due to 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.
Further, 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 provided on both sides of the submount substrate 20 sandwiching the LD chip 10. Of these, it is located 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.

Suppressing 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 miniaturization of.
The chip-on-submount element 6 shown in FIG. 3 also corresponds to an example of a semiconductor laser device to be manufactured by the method for manufacturing a semiconductor laser device of the present invention.

Next, an embodiment of the method for manufacturing a semiconductor laser device of the present invention will be described.
4 and 5 are views showing an embodiment of the method for manufacturing a semiconductor laser device of the present invention. FIG. 4 shows steps A to D, which are the front-stage portions in one embodiment of the manufacturing method, and FIG. 5 shows steps E to G, which are the rear-stage parts in one embodiment of the manufacturing method. Has been done.
In the present embodiment, first, in the 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 the chip fixing step described in the present invention. Further, in this step A, the pole on the lower surface side of both 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 also corresponds to a part of the connection step referred to in the present invention.
Next, in step B shown in FIG. 4, the electrode on the upper surface side of both electrodes 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 connection 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 energizing pin 50 is pressed against the pin regions 21a and 22a on the submount substrate 20, and the energizing pin 50 dissipates 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. Further, the heat radiating plate 60 is, for example, a heat radiating plate made of aluminum and has high heat radiating properties. This step C corresponds to an example of the pressing step referred to in the present invention.
Next, in step D shown in FIG. 4, electric power is applied to the energizing pin 50 to energize the LD chip 10 via the electrodes on the submount substrate 20. This step D corresponds to an example of the energization step referred to in the present invention.

In step D in the present embodiment, as energization for the LD chip 10, energization for applying a load to the LD chip 10, which is called burn-in, is performed.
Specifically, a high current close to, for example, the maximum rated current is passed through the LD chip 10 in a state where the constant temperature bath is connected to the heat radiation plate 60, and the laser beam L is, for example, at a high temperature close to the maximum rated temperature. Continuous light emission is performed.
Since a high current flows in step D as described above, the pressing in step C needs to be sufficiently strong, but the energizing pin 50 is pressed against the pin regions 21a and 22a 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 region having a sufficient area such as φ0.3 mm is prepared as the pin regions 21a and 22a, a high current can be energized.
The energization in this burn-in is, for example, energization for a long time over about one day, and as a result of energization with a high current for such a long time, the carriers in the LD chip 10 are activated and the characteristics of the LD chip 10 are improved. Stabilize.

On the contrary, when the LD chip 10 has a crystal defect (that is, it is a defective product), it is easy because the crystal is deteriorated by the load due to the energization of a high current for a long time and the characteristic deterioration is clear. Defective products are sorted out and eliminated. Therefore, since only the good chip-on-submount element 6 is incorporated in the semiconductor laser device 1, the reliability of the product is improved, the loss of the member is reduced, and the cost is excellent.

In the manufacturing method of the present embodiment, after step D shown in FIG. 4, the process proceeds to step E shown in FIG. 5, and the energizing pin 70 for characteristic inspection is pressed against the pin regions 21a and 22a again, and the chip-on-submount element is pressed. 6 is attached to the heat radiating plate 80 for characteristic inspection. The heat radiating plate 80 for characteristic inspection has a heat radiating capacity equivalent to that of the metal case 2 of the semiconductor laser device 1 shown in FIG. 1, and since a constant temperature bath or the like is not connected, the heat radiating plate 80 has characteristics around it. Sufficient space for inspection is secured.

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 pin 70. This step F corresponds to an example of the inspection step referred to in the present invention. The characteristics inspected here include, for example, the oscillation threshold value 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, and the input current value and input voltage. Corresponding curve with 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 the measurement. For example, energization by pulse operation. Conversely, in the above-mentioned burn-in, it can be said that energization is performed for a longer time than energization for characteristic inspection, and it can be said that energization with a higher current than energization for characteristic inspection is performed. For example, energization by continuous operation (CW operation). By such a characteristic inspection, a guaranteed value as a product can be obtained, and defective products with less characteristic deterioration such as those not excluded in step D shown in FIG. 4 are surely selected and eliminated, so that the reliability of the product is obtained. The sex is further improved.

In the present embodiment, the step F is executed after the step D due to space and the like, but the inspection step referred to in the present invention may be a step executed at the same time as the energization step 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, and the module 3 shown in FIG. 2 is formed. This step G corresponds to an example of the element fixing step referred to in the present invention. By step G after passing through step D and the like, a module 3 having high reliability, which does not include a defective chip-on-submount element 6, can be obtained.
In the present embodiment, after the step G shown in FIG. 5, the module 3 is incorporated in the metal case 2 shown in FIG. 1, and the wiring and the glass window are also incorporated to complete the semiconductor laser apparatus 1. Illustration is omitted.

Next, a modification to the embodiment described above will be described.
The first modification is the same as the above-described embodiment except that the 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.
FIG. 6A shows a top view, and FIG. 6B shows a cross-sectional view.
The chip-on-submount element 100 in the first modification 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. 3, but the submount substrate 110 The upper electrodes 111 and 112 are arranged in a state of being retracted from the edge of the insulating substrate 23. Since the electrodes 111 and 112 are retracted from the edge of the insulating substrate 23 in this way, the electrodes 111 and 112 are surely attached to the heat radiating plates 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. 7 (A) shows a top view, and FIG. 7 (B) shows a sectional view.
The chip-on-submount element 200 in the second modification includes a low-output 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 the LD chip 210 is fixed on the submount substrate 220.

Further, a plurality of electrodes 221,222 isolated from each other are provided on the submount substrate 220, and the electrodes 221,222 are arranged so as to be arranged in the longitudinal direction of the submount substrate 220. However, the resonators of the LD chip 210 are arranged side by side in the width direction instead of the length direction. When the length of the resonator 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 the miniaturization of the apparatus. Also in the case of this second modification, it is assumed that pin regions 221a and 222a having a diameter of 0.3 mm corresponding to burn-in due to a high current are secured in each electrode 221,222.

Further, in the second modification, it is not intended to increase the output of the device, and a so-called can-type semiconductor laser device 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 (excluding step G). Therefore, the destruction and shortening of the life of the LD chip 210 due to the pressing of the energizing pin in burn-in are suppressed.

1 ... semiconductor laser device, 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 (11)

A chip fixing step in which a plurality of electrodes electrically separated from each other are arranged on the surface and the laser chip is fixed on a submount substrate incorporated in a semiconductor laser element together with the laser chip.
A connection step in which both electrodes of the laser chip are electrically and independently connected to each electrode on the submount substrate.
After the connection step, a pressing step of contacting each electrode with an energizing pin on only one of both sides of the submount substrate sandwiching the laser chip and pressing the submount substrate against the heat dissipation plate by the energizing pin.
An energization step of energizing the laser chip via the energizing pin and each of the electrodes,
A method for manufacturing a semiconductor laser device, which is characterized by passing through. An element fixing step of fixing a plurality of chip-on-submount elements having the submount substrate and the laser chip and undergoing the energization step to one heat sink that absorbs heat generated by the laser chip due to light emission. The method for manufacturing a semiconductor laser device according to claim 1 , further comprising the above. The semiconductor laser device according to claim 1 or 2, wherein a single chip-on-submount element having the submount substrate and the laser chip undergoes a further inspection step of inspecting the characteristics of the laser chip. Production method. The method for manufacturing a semiconductor laser device according to any one of claims 1 to 3, wherein the energization step is a step of energizing for burn-in to the laser chip. The manufacture of the semiconductor laser device according to any one of claims 1 to 4, wherein the energization step is a step of energizing for a longer period of time than the energization for the characteristic inspection of the laser chip. Method. A submount substrate with multiple electrodes electrically separated from each other arranged 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.
It is a chip-on-submount element that is incorporated into a semiconductor laser element and is equipped with.
A chip-on-sub characterized in that a plurality of electrodes used for burn-in to the laser chip among the plurality of electrodes are arranged on only one of both sides of the submount substrate sandwiching the laser chip. Mount element. A submount board with multiple electrodes electrically separated from each other arranged 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.
It is a chip-on-submount element that is incorporated into a semiconductor laser element and is equipped with.
Of the plurality of electrodes, any one or more of the electrodes used to energize the laser chip are arranged on only one of both sides of the submount substrate sandwiching the laser chip, and the length of the resonator of the laser chip. A chip-on-submount element characterized in that the direction is the longitudinal direction of the submount substrate. Wherein one side only arranged a plurality of electrodes, a chip-on-submount device according to claim 6 or 7, wherein the in which are disposed side by side in the longitudinal direction of the sub-mount substrate. The chip according to any one of claims 6 to 8, wherein the plurality of electrodes arranged only on one side are arranged side by side in the length direction of the resonator of the laser chip. On-submount element. The laser chip is fixed at a position deviated from the center of the submount substrate.
Any of claims 6 to 9, wherein the plurality of electrodes arranged only on one side are arranged on the wider side of both sides of the submount substrate sandwiching the laser chip. The chip-on-submount element according to item 1. A submount board with multiple electrodes electrically separated from each other arranged 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 to which the submount substrate is fixed and the laser chip absorbs the heat generated by light emission,
A heat radiating body that dissipates heat absorbed by the heat sink,
Is incorporated ,
A semiconductor laser device characterized in that a plurality of electrodes used for burn-in to the laser chip among the plurality of electrodes are arranged on only one of both sides of the submount substrate sandwiching the laser chip. ..

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