JP2010199274A - Semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device that reduces effect due to thermal interference in a plurality of aligned semiconductor laser chips, and ensures thermal uniformity in each semiconductor laser chip. <P>SOLUTION: In the semiconductor laser device in which a plurality of semiconductor laser chips are arranged on a substrate, some of the semiconductor laser chips are mounted face down and some are mounted face-up. The substrate has a step on its surface. Each semiconductor laser chip is mounted face up on a step bottom of the substrate and mounted face down on a step upper part of the substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser array device in which a plurality of semiconductor laser chips are arranged.

  Since semiconductor laser devices require high-power laser light, semiconductor laser array devices in which a plurality of semiconductor laser chips are arranged are being studied.

  An example of the semiconductor laser array apparatus is one in which a laser bar 312 die-bonded to a submount or a heat sink 311 is arranged as shown in FIG. This laser bar is a multicavity semiconductor laser provided with a plurality of light emitting regions 312a. The interval between the light emitting regions inside such a laser bar is narrow, and the heat generated inside the laser bar tends to cause interference. When thermal interference occurs, the temperature inside the laser bar rises, and in particular, the temperature rises in the light emitting region, leading to deterioration of the light emitting region, and as a result, the life characteristics of the laser bar are lowered.

  As another example of the semiconductor laser array device, there is one in which a plurality of semiconductor laser chips are evenly arranged with a predetermined interval on a substrate such as a submount or a heat sink. Each of these semiconductor laser chips is provided with electrodes, and when a current is injected into these electrodes, each semiconductor laser chip operates independently, and laser light is emitted from the light emitting region formed in each semiconductor laser chip. Is output.

  In the structure of such a semiconductor laser device, although it is the above-mentioned substrate that acts as a heat sink for cooling the heat generated during the operation of each semiconductor laser chip, the semiconductor laser chip is arranged close to the substrate, There was a problem that thermal interference occurred.

  As shown in FIG. 7, when a plurality of semiconductor laser chips (LD1 to LD3 in order from the end) are arranged at equal intervals on the submount, thermal interference occurs between adjacent semiconductor laser chips, so that the semiconductor laser chip There is concern about the temperature rise. As a result, the semiconductor laser chip that has been confirmed to rise in temperature has a problem in that the optical output decreases and the current tends to concentrate, and the life of the semiconductor laser chip itself is shortened.

  In order to prevent such thermal interference of the semiconductor laser device, the arrangement interval of the plurality of semiconductor laser chips arranged on the submount is adjusted (Patent Document 2), or the submount in which the plurality of semiconductor laser chips are arranged (Patent Document 4) discloses forming a groove between a semiconductor laser chip and another semiconductor laser chip adjacent to the semiconductor laser chip. Further, in order to improve the heat dissipation of the semiconductor laser device, a recess for arranging the semiconductor laser chip is provided in the submount, and a partition wall is formed between the recesses, and then the semiconductor laser chip is juxtaposed for each recess (Patent Document) 1) is disclosed. In addition, adjusting the thickness of the submount and the distance between the centers of the semiconductor laser chips (Patent Document 3) is disclosed. It is difficult to suppress thermal interference in the submount only by forming a partition wall between the recesses, and these semiconductor laser device configurations have insufficient heat uniformity and heat dissipation in each semiconductor laser chip. .

JP 2003-37323 A JP 2003-209313 A JP 2006-13038 A JP 2006-13057 A

  An object of the present invention is to provide a semiconductor laser device capable of reducing the influence of thermal interference in a plurality of semiconductor laser chips arranged on a substrate such as a submount and ensuring thermal uniformity in the substrate, and a method for manufacturing the same. It is to be. Also provided are a semiconductor laser device and a method for manufacturing the same, which can efficiently dissipate heat generated by the simultaneous operation of a plurality of semiconductor laser chips to keep the operating temperature of each semiconductor laser chip constant. That is.

  The present invention has been made to solve the above problems, and in a semiconductor laser device in which a plurality of semiconductor laser chips are arranged on a substrate, the semiconductor laser chip is mounted face-down and face-up mounted. A step is formed on the surface of the substrate, the semiconductor laser chip is mounted face-up on the bottom of the step, and a semiconductor laser chip is mounted on the top of the step. It is mounted face down.

  In the present invention, a plurality of semiconductor laser chips are mounted face-up on the step bottom of the substrate and mounted face-down on the step upper portion (region other than the bottom) of the substrate. The range and heat density of the heat spreading in can be adjusted. First, the height difference of the heat spread in the substrate, the range of the heat in the vertical direction, and the heat density can be adjusted by the step of the substrate. Also, by arranging the semiconductor laser chip mounted face-up and the semiconductor laser chip mounted face-down on the same substrate, it is possible to adjust the width of heat spreading in the substrate, the lateral range of heat and the heat density. it can. As a result, the heat transferred from the semiconductor laser chip to the substrate can be prevented from being concentrated locally, and thermal interference can be suppressed.

  Also, by combining a plurality of semiconductor laser chips arranged on the substrate with those that are mounted face-down and those that are mounted face-up, the height of the light emitting region on the substrate having a step can be adjusted. The height of the light emitting region of the semiconductor laser chip on the substrate can be made substantially uniform.

  The present invention has been made to solve the above problems, and in a method of manufacturing a semiconductor laser device in which a plurality of semiconductor laser chips are arranged on a substrate, a step of preparing a substrate having a step formed on the surface; Mounting the semiconductor laser chip face-up on the step bottom of the substrate, and mounting the semiconductor laser chip face-down on the top of the step (a region other than the bottom) of the substrate. It is characterized by.

  By forming the semiconductor laser device by such a manufacturing method, it is possible to easily adjust the heat range and heat density spreading in the substrate, and to suppress thermal interference. Further, the temperature rise of each semiconductor laser chip is not biased, and the thermal uniformity of each semiconductor laser chip can be ensured. In addition, when semiconductor laser chips are electrically connected in parallel, there is no semiconductor laser chip in which current increases due to temperature rise. Therefore, the present invention prevents the life of the semiconductor laser chip from being shortened due to such a cause. be able to. Further, when the semiconductor laser chips are electrically connected in series, the output of the semiconductor laser chip disposed inside is lowered due to the temperature rise. However, the present invention can also solve such a problem.

  According to the semiconductor laser device of the present invention, it is possible to suppress the thermal interference generated between the semiconductor laser chips, and to ensure the thermal uniformity of each semiconductor laser chip. It is possible to prevent the lifetime of the semiconductor laser chip from being shortened by suppressing the concentration of current in the semiconductor laser chip due to the temperature rise of the specific semiconductor laser chip. Further, according to the semiconductor laser device of the present invention, thermal saturation in the substrate can be suppressed. Further, the semiconductor laser device according to the present invention can uniformly align the heights of the light emitting points of each semiconductor laser chip, and the interval between the light emitting points can be adjusted within a short distance. The laser device is also suitable for a combined laser light source.

It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is sectional drawing of the semiconductor laser apparatus in one Embodiment. It is an image figure which shows the heat propagation route in the semiconductor laser apparatus of this invention. It is a graph which shows the mounting pattern of the semiconductor laser chip in the semiconductor laser apparatus of this invention, and the temperature of a semiconductor laser chip. It is sectional drawing of the semiconductor laser apparatus of a prior art example. It is sectional drawing of the semiconductor laser apparatus of a prior art example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing the configuration of the semiconductor laser device according to the present embodiment. In the semiconductor laser device 30 of this embodiment, a plurality of semiconductor laser chips 20 are arranged on a substrate 10. The semiconductor laser chip 20 includes a semiconductor laser chip 20a mounted face up and a semiconductor laser chip 20b mounted face down. A step is formed on the surface of the substrate 10, the semiconductor laser chip is mounted face-up on the step bottom 10a of the substrate, and a semiconductor laser is formed on the step upper portion (region other than the bottom) 10b of the substrate. The chip is mounted face down.

  In FIG. 1, a step bottom 10a, a step top 10b, and a step bottom 10a are formed in this order from the left end on the surface of a substrate 10 made of a heat sink. On this substrate, three semiconductor laser chips 20 are arranged in order of a semiconductor laser chip 20a mounted face up from the left end, a semiconductor laser chip 20b mounted face down, and a semiconductor laser chip 20a mounted face up. . Note that FIG. 1 illustrates one embodiment of the present invention, and the present invention is not limited to such a structure.

  Thus, it is preferable that the semiconductor laser chip disposed at the end portion of the substrate 10 of the present invention is the semiconductor laser chip 20a mounted face up. The reason is that in the semiconductor laser chip mounted face up, the heat from the light emitting point 16 is once dispersed by the semiconductor laser chip and radiated to the substrate 10 with the width of the semiconductor laser chip, so that the end portion of the substrate is also used as a heat radiating region. This is because it can be used efficiently. In addition, the above-described configuration can suppress thermal interference between the semiconductor laser chips.

  In addition, the semiconductor laser chips disposed on both ends of the substrate 10 of the present invention are more preferably semiconductor laser chips 20a mounted face up. The reason for this is that in the semiconductor laser chip mounted face-up, the heat from the light emitting point is once dispersed by the semiconductor laser chip and radiated to the substrate 10, so that both ends of the substrate can be efficiently used as a heat dissipation region. Because it can. Further, thermal interference between the semiconductor laser chips can be suppressed.

  The chip width of the semiconductor laser chip 20 of the present invention is preferably narrower for face-down mounting than for face-up mounting. The semiconductor laser chip mounted face down does not depend on the chip width for heat dissipation efficiency compared to the semiconductor laser chip mounted face up. Therefore, even if the semiconductor laser chip mounted face-down has a narrow chip width, the distance between the light emitting points in the semiconductor laser device can be made closer without deteriorating the high heat dissipation efficiency.

  In the semiconductor laser chip 20 of the present invention, adjacent semiconductor laser chips are preferably electrically connected to each other. This eliminates the need to connect the substrate and the semiconductor laser chip with a wire. In addition, when semiconductor laser chips are electrically connected in series, by providing a wiring pattern on the substrate, it is not necessary to mount wires from a face-up mounted semiconductor laser chip to a face-down mounted semiconductor laser chip. The semiconductor laser device can be operated only by wire mounting from the semiconductor laser chip mounted face down to the semiconductor laser chip mounted face up. As another form, wire mounting from a semiconductor laser chip mounted face down to a semiconductor laser chip mounted face up is eliminated, and from a semiconductor laser chip mounted face up to a semiconductor laser chip mounted face down. It is also possible to operate the semiconductor laser device only with the wire mounting. Therefore, a semiconductor laser device having a structure in which a semiconductor laser chip mounted face-down and a semiconductor laser chip mounted face-up are disposed adjacent to each other is effective for miniaturization.

  In the semiconductor laser chip 20 of the present invention, it is preferable that the semiconductor laser chip 20a mounted face up and the semiconductor laser chip 20b mounted face down are alternately arranged. With this configuration, all adjacent semiconductor laser chips can be electrically connected not only by wires but also by pattern wiring on the substrate. Therefore, for example, wire mounting from face-up mounting to face-down mounting becomes unnecessary, and the semiconductor laser device can be further downsized. On the other hand, in the conventional semiconductor laser device as shown in FIG. 7, in order to operate each semiconductor laser chip, it is necessary to wire-mount the semiconductor laser chip and the substrate. It was necessary to provide a wire mounting area.

  In the semiconductor laser device 30 of the present invention, the light emitting points of the semiconductor laser chips arranged on the substrate are preferably at substantially the same height. In the case of semiconductor laser chips arranged in the same mounting pattern on a flat substrate, the heights of the light emitting points on the substrate are substantially the same, but heat radiation is insufficient and there is a problem of thermal interference. The semiconductor laser device 30 of the present invention solves such problems as thermal interference, but has a structure in which the semiconductor laser chip 20 is mounted on the substrate 10 having a level difference. There is also a new problem that the height is different. However, if the semiconductor laser device of the present invention, the height difference of the step formed on the substrate surface, the height difference of the light emitting point between the semiconductor laser chip mounted face-up and the semiconductor laser chip mounted face-down, By adjusting the height, the height of the light emitting point 16 on the substrate 10 can be made substantially the same, so that such a problem is also solved.

  The stepped side surface 10c of the substrate 10 is preferably arranged so as not to contact the semiconductor laser chip 20a face-up mounted on the stepped bottom 10a of the substrate via the bonding material 40. This configuration is such that the stepped side surface 10c of the substrate 10 is spaced apart from the side surface of the semiconductor laser chip 20a. As shown in FIG. 5, which is an image diagram of the heat propagation route, the heat emitted from the semiconductor laser chip 20b face-down mounted on the stepped upper surface 10b of the substrate expands on the surface of the stepped upper surface 10b of the substrate and extends in the lower direction of the substrate Propagate to. Since heat diffusion occurs in the direction and range of such an arrow, heat is also propagated around the step side surface 10c. If there is heat propagation from the side surface of the semiconductor laser chip 20a in the region a around the stepped side surface 10c, there is a possibility that thermal interference occurs in the region a. However, according to the semiconductor laser device of the present invention, the stepped side surface 10c of the substrate 10 is disposed away from the side surface of the semiconductor laser chip 20a (region b), and thus such a problem is solved. . Further, the heat propagated from the semiconductor laser chip 20a to the substrate side through the bonding material 40 diffuses to the region c, but the heat propagated from the semiconductor laser chip 20b mounted face-down to the substrate side is a region immediately below the ridge. However, since the density of heat propagated from the semiconductor laser chip 20b to the region c is low, the heat density is not so high in the region c, which affects the continuous operation of the semiconductor laser device. There are few.

  In this method of forming the substrate 10, a step formed on the surface of the substrate is formed by etching or grinding. As another substrate forming method, a flat substrate is prepared, and a substrate having a concavo-convex shape is obtained by bonding the same member or another member to the substrate at a predetermined interval. There is something to form. When a different member is joined on the substrate to form a substrate having a concavo-convex shape and a step, the thermal diffusion range and the heat density can be adjusted by changing the thermal conductivity of the substrate and the different member.

The thickness of the substrate 10 is 50 to 5000 μm. The height (h) of the substrate side surface 10c is 20 to 300 μm. The width of the step bottom 10a of the substrate is 100 to 2000 μm. Also, the floor area is 0.05~12mm ^2. The shape of the step side surface of the substrate is preferably perpendicular to the step bottom 10a. The width of the stepped upper portion 10b of the substrate is 50 to 1000 μm. The thermal conductivity of the substrate is 50 to 2000 W / (m · k).
Further, the substrate is not limited to one formed from a single member, and may be a laminate of a plurality of members.

In the present invention, the substrate 10 plays a role of releasing heat generated in the semiconductor laser element, and preferably has a higher thermal conductivity than the semiconductor layer and the growth substrate constituting the semiconductor laser element. . The substrate 10 preferably has a thermal expansion coefficient close to that of the semiconductor laser element and can relieve thermal stress with the semiconductor laser element. Further, the substrate 10 preferably has a surface made of an inorganic material instead of an organic material. As a specific material of the substrate 10, it is preferable to include any or all of materials (for example, AlN, diamond, Cu-diamond) that can release heat in a predetermined direction. In addition, a semiconductor laser device having a self-shape holding force as another function is preferable because the semiconductor laser device can be easily assembled. Examples of the substrate having such a function include alumina (Al ₂ O ₃ ), SiC, AlN, Cu, Ag, Cu—W, Cu—Mo, Cu—diamond, diamond, carbon, Si, GaN, and the like. Other names for the substrate include a submount and a heat sink, and the submount may be formed on the heat sink.

  The semiconductor laser chip 20 is a semiconductor structure in which a semiconductor layer is stacked on a semiconductor substrate or an insulating substrate, which is a substrate for growing a semiconductor layer, to form a laser structure. For example, a GaN substrate is prepared as a growth substrate, a semiconductor layer including an active layer is laminated on the growth surface side which is one main surface of the GaN substrate, and a p-electrode is formed on the uppermost surface of the semiconductor layer. Yes. Further, an n-electrode is formed as a back electrode on the main surface of the GaN substrate opposite to the growth surface side of the semiconductor layer. Such a semiconductor laser chip 20 is mounted on the substrate 10 via a bonding material 40 such as solder. The plurality of semiconductor laser chips means two or more semiconductor laser chips. In the present invention, three or more semiconductor laser chips are preferable. This is because the effect of the present invention is more remarkable in the semiconductor laser device 30 having three or more semiconductor laser chips.

As an example of the semiconductor laser chip 20, there is one in which a GaN compound semiconductor is stacked on a GaN substrate. This GaN-based compound semiconductor includes an n-side semiconductor layer 21, an active layer 22, and a p-side semiconductor layer 23. A GaN-based compound semiconductor is obtained by stacking semiconductor layers represented by the general formula In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). . In addition to this, an element in which B is partially substituted as a group III element may be used, or an element in which a part of N is substituted with P or As may be used as a group V element. The n-side semiconductor layer 21 may contain one or more group IV elements or group VI elements such as Si, Ge, Sn, S, O, Ti, Zr, and Cd as n-type impurities. The p-side semiconductor layer 23 contains Mg, Zn, Be, Mn, Ca, Sr, etc. as p-type impurities. These impurities are preferably contained in a concentration range of, for example, about 5 × 10 ¹⁶ / cm ³ to 1 × 10 ²¹ / cm ³ . Further, all of the semiconductor layers stacked in multiple layers may not contain impurities. The active layer 22 may have either a single quantum well structure or a multiple quantum well structure. The light emitting point 16 means a region including at least a well layer constituting an active layer.
A ridge is formed in the semiconductor laser chip, and an insulating current confinement layer is formed on both sides of the ridge. An electrode is formed on the upper surface of the ridge. In the case of the semiconductor laser chip 20a to be mounted face up, wire bonding is performed on this electrode.

  The width of the semiconductor laser chip is 50 μm to 1000 μm, and the resonator length of the semiconductor laser chip is 200 μm to 5000 μm. Further, the semiconductor laser chip 20a mounted face-up and the semiconductor laser chip 20b mounted face-down may have different semiconductor laser chip widths and resonator lengths. It is preferable to make the chip width of the semiconductor laser chip 20b mounted face down narrower than the chip width of the semiconductor laser chip 20a mounted face up. As a result, the distance between the light emitting points can be made closer.

The face-up mounting is a mounting structure of the semiconductor laser chip 20 arranged on the substrate 10, and the back electrode side formed on the growth substrate of the semiconductor laser chip 20 is arranged on the substrate 10 through the bonding material 40. This is a mounting structure.
The face-down mounting is a mounting structure of the semiconductor laser chip 20 disposed on the substrate 10, and the p-electrode side formed on the uppermost surface of the semiconductor layer of the semiconductor laser chip 20 is placed on the substrate 10 via the bonding material 40. It is a mounting structure to be arranged in. This mounting structure is a mounting structure in which the p-electrode is formed on the ridge formed in the semiconductor layer in the semiconductor laser chip of the present embodiment, and the bonding material 40 is disposed on the p-electrode.

  As another embodiment of the present invention, as shown in FIG. 2, a step bottom 10a, a step top 10b, a step bottom 10a, a step top 10b, and a step bottom 10a are arranged in this order from the left end on the surface of the substrate 10 made of a heat sink. Is formed. On this substrate, five semiconductor laser chips 20 are face-up mounted from the left end, a semiconductor laser chip 20a, a face-down mounted semiconductor laser chip 20b, a face-up mounted semiconductor laser chip 20a, and a face-down mounted. The semiconductor laser chip 20b and the semiconductor laser chip 20a mounted face up are arranged in this order. Thus, by alternately arranging the semiconductor laser chips that are mounted face-up and those that are mounted face-down, wire mounting from face-up mounting to face-down mounting is not necessary, and the effect of miniaturization can be achieved. is there. The semiconductor laser device of this embodiment can suppress thermal interference that occurs between semiconductor laser chips, and can suppress thermal saturation in the substrate. In addition, in FIG. 2 which shows this embodiment, members, such as a wire and another electrode, are not illustrated.

  As another embodiment of the present invention, as shown in FIG. 3, a step bottom 10a, a step top 10b, and a step bottom 10a are sequentially formed from the left end on the surface of a substrate 10 made of a heat sink. Five semiconductor laser chips 20 are mounted on this substrate. A semiconductor laser chip 20a mounted face-up is disposed on the step bottom 10a of the substrate from the left end, and then three semiconductor laser chips 20b are mounted face-down on the step upper portion 10b. Further, a semiconductor laser chip 20a mounted face up is disposed at the right end. As a semiconductor laser device, a plurality of face-down mounted semiconductor laser chips 20b are arranged between the face-up mounted semiconductor laser chip 20a and the face-up mounted semiconductor laser chip 20a. A higher light output can be obtained. In addition, in FIG. 3 which shows this embodiment, members, such as a wire and another electrode, are not illustrated.

  As another embodiment of this invention, as shown to FIG. 4A-FIG. 4C, the board | substrate 10 is formed in two steps. This substrate 10 is a substrate in which a second substrate 12 is formed on a first substrate 11, and the cross-sectional shape is uneven. In the semiconductor laser device shown in FIG. 4A, three semiconductor laser chips 20 are arranged on a substrate. The semiconductor laser chip 20a is mounted face up from the left end, the semiconductor laser chip 20b is mounted face down, and the face up is performed. The semiconductor laser chips 20a are arranged in this order. Here, the semiconductor laser chip 20 b mounted face down is disposed on the first substrate 11 via the second substrate 12. The exposed surface of the first substrate 11 is a step bottom portion of the substrate in other embodiments, and the second substrate 12 is a step top portion. As a method of manufacturing a semiconductor laser device having such a structure, a flat first substrate 11 is first prepared. Next, a second substrate 12 is prepared, and a semiconductor laser chip mounted facedown on the second substrate is prepared. Next, a semiconductor laser chip is mounted face up on the flat first substrate 11. Finally, avoiding the region where the semiconductor laser chip 20a mounted face up is disposed, the second substrate 12 having the semiconductor laser chip mounted face down is disposed in the region where the first substrate is exposed. . By mounting the semiconductor laser chips in this process order, it is possible to suppress interference of the mounting jig with the adjacent chips. Further, by using a different member different from the first substrate for the second substrate, there is a stress relaxation effect on the chip at the time of face-down mounting. For example, when the thermal expansion coefficients of the substrate and the semiconductor laser chip are different, the stress on the face-down mounted chip becomes larger. In order to avoid this, a member having substantially the same thermal expansion coefficient as that of the semiconductor laser chip to be face-down mounted is used for the second substrate 12.

  The semiconductor laser device shown in FIG. 4B has a structure in which five semiconductor laser chips 20 are arranged on a substrate. A semiconductor laser chip 20a mounted face up from the left end is arranged, then three semiconductor laser chips 20b mounted face down are arranged, and further, a semiconductor laser chip 20a mounted face up is arranged at the right end. Is arranged. Here, the three semiconductor laser chips 20 b mounted face-down are arranged on the first substrate 11 via the second substrate 12. Similar to the structure of FIG. 4A, the exposed surface of the first substrate 11 is the bottom of the step in the substrate in other embodiments, and the top of the second substrate 12 is the top of the step. With such a configuration, a higher light output can be obtained as a semiconductor laser device, and the same effect as the semiconductor laser device shown in FIG. 4A can be obtained.

  The semiconductor laser device shown in FIG. 4C has a structure in which three semiconductor laser chips 20 are arranged on a substrate. The semiconductor laser chip 20a is mounted face up from the left end, and the semiconductor laser chip is mounted face down. 20b and the semiconductor laser chip 20a mounted face-up are arranged in this order. Both the semiconductor laser chip 20a mounted face up and the semiconductor laser chip 20b mounted face down are disposed on the first substrate 11 via the second substrate 12. With such a configuration, an electrical wiring that does not depend on the electrical conductivity of the substrate can be realized. Moreover, a multi-wavelength laser light source can be realized by selecting each second substrate in accordance with the thermal expansion coefficient of each semiconductor laser chip.

  In the semiconductor laser device shown in FIG. 4C, three semiconductor laser chips 20 are arranged on a substrate. The semiconductor laser chip 20a is mounted face up from the left end, the semiconductor laser chip 20b is mounted face down, and the face up is performed. The semiconductor laser chips 20a are arranged in this order. This substrate is composed of a first substrate and a second substrate. For example, only the second substrate on which the semiconductor laser chip 20a is mounted is made the same member as the first substrate, and the second substrate on which the semiconductor laser chip 20b is mounted is made of a member different from the first substrate. Even in such a configuration, a semiconductor laser device having the above-described effects can be realized.

The bonding material 40 is for bonding the semiconductor laser chip and the substrate. Further, this bonding material is for bonding substrates together. Examples of the material of the bonding material include gold (Au), silver (Ag), tin (Sn), and the like. For example, alloys such as Au—Sn and Ag—Sn, Ag paste, Ti—Pt—Au, An example is heat fusion having a multilayer structure such as Ti—Pt—Au—Pt.
When the substrate includes a submount and a heat sink, the submount is disposed on the heat sink via a bonding material on a surface opposite to the surface on which the semiconductor laser chip is mounted. The bonding material here is not particularly limited, but is eutectic material such as Au—Sn, Ag—Sn solder.

  In wire bonding, the wire bond from the face-up mounted semiconductor laser chip 20a at the left end of FIG. 1 to the adjacent face-down mounted semiconductor laser chip 20b can be omitted by electric wiring on the substrate. In addition, since the semiconductor laser chips mounted face-down and the semiconductor laser chips mounted face-up are alternately mounted, the semiconductor laser chips can be directly wire-bonded to each other, so that they are electrically connected in series. It becomes easy.

When the semiconductor laser device of the present invention is optically coupled in the array lens, the coupling loss can be reduced by the uniform emission point height of the semiconductor laser chip.
Further, by changing the oscillation wavelength of each semiconductor laser chip, it is possible to obtain a compact other wavelength laser light source that ensures thermal uniformity. In particular, an RGB laser light source can be realized by setting the wavelength of each semiconductor laser chip to 430 to 480 nm in the blue band, 490 to 570 nm in the green band, and 580 to 780 nm in the red band. Further, by setting the wavelength of each semiconductor laser chip to 770 to 790 nm, 640 to 660 nm, and 400 to 410 nm, a three-wavelength light source for CD / DVD / Blu-ray can be realized.

As a mounting condition of the semiconductor laser chip, no load may be applied in the case of face-up mounting, but the solder material as a bonding material is melted while preferably pressing with a pressing force of several tens to several hundreds g / cm ^2. The substrate is heated to a temperature with a heater to melt the solder material. The mounting conditions for face-down mounting of the semiconductor laser chip may be no load, but preferably a temperature at which the solder material as the bonding material melts while pressing with a pressing force of several tens to several hundreds g / cm ^2. The substrate is heated by a heater until the solder material is melted. At this time, when using an Sn-based solder material, it is preferable to perform heating in an inert gas atmosphere such as nitrogen.
In the method of manufacturing the semiconductor laser device of this embodiment, first, a plurality of semiconductor laser chips and a substrate having a step formed on the surface are prepared. Next, the semiconductor laser chip is face-up mounted on the step bottom of the substrate under the above-described conditions. Next, the semiconductor laser chip is face-down mounted on the stepped portion of the substrate under the conditions described above. The semiconductor laser device formed by such a process can easily adjust the heat range and heat density spreading in the substrate, and can suppress thermal interference.

  As an embodiment of the present invention, a semiconductor laser device in which a semiconductor laser chip 20a face-up mounted, a semiconductor laser chip 20b face-down mounted, and a semiconductor laser chip 20a mounted face-up on a substrate having a step are arranged in order. Use. As a comparative example, a semiconductor laser device in which three semiconductor laser chips mounted face-up on a flat substrate are used. FIG. 6 is a graph in which the vertical axis represents the temperature difference between the light emitting points of each semiconductor laser chip when this semiconductor laser device is operated, and the horizontal axis represents the distance between the light emitting points between the semiconductor laser chips. Here, the number of semiconductor laser chips is three, and the intervals between the semiconductor laser chips are as follows: the height of the step is 85 μm, the width of the step top 10 b is 300 μm, the width of the step bottom 10 a is 1500 μm, and the step bottom 10 a to the substrate bottom. Is set to 200 μm. The width of the semiconductor laser chip is 200 μm, and the cavity length of the semiconductor laser chip is 1200 μm. The thermal conductivity of the substrate 10 is 230 W / (m · k). The graph shown in FIG. 6 is a simulation result when the amount of heat generated by each semiconductor laser chip is 5 W. From this graph, it can be seen that the embodiment of the present invention has a smaller temperature difference between the emission points of the semiconductor laser chips during the operation of the semiconductor laser device than the comparative example, and maintains the thermal uniformity of the semiconductor laser chips. Recognize. This effect becomes more prominent as the distance between the light emitting points of the semiconductor laser chip becomes shorter. In addition, when there is a temperature difference between the light emitting points as in the comparative example between the semiconductor laser chips, the input current value to the semiconductor laser chip having a high light emitting point temperature increases. Along with this, the amount of heat generated between the semiconductor laser chips and the temperature difference between the light emitting points increase, and this chain is repeated, resulting in variations in the life characteristics of the semiconductor laser chips. Compared with the case where the semiconductor laser chip is arranged only by face-up mounting, the semiconductor laser device arranged by combining face-up mounting and face-down mounting according to the present invention has an active layer of the semiconductor laser chip in the case of the same emission point distance. The temperature difference is decreasing. That is, the semiconductor laser device of the present invention can further reduce the light emitting point distance of the semiconductor laser chip as compared with the case where the semiconductor laser chip is arranged only by face-up mounting. From the above results, it can be seen that the reliability of the semiconductor laser device of the present invention is further improved, and the semiconductor laser device can be downsized.

  The above simulation data is based on a semiconductor laser chip in which a GaN compound semiconductor is stacked on a GaN substrate. The semiconductor laser chip in the present invention is a gallium nitride (GaN) compound semiconductor. The present invention is not limited, and the present invention can also be applied to other materials such as gallium arsenide (GaAs) compound semiconductors and indium phosphide (InP) compound semiconductors.

  The semiconductor laser device according to the present invention can be used for all applications that employ laser light as a light source. For example, as a light source used for illumination, exposure, display, printing, analysis, etc., an optical disc system capable of recording / reproducing and recording information such as CD / MD / DVD / Blu-ray, medical light source, laser printer, light source used for optical communication network It can be used in various fields.

DESCRIPTION OF SYMBOLS 10 Substrate 11 Submount 12 Heat sink 16 Light emitting point 20 Semiconductor laser chip 21 N side semiconductor layer 22 Active layer 23 P side semiconductor layer 30 Semiconductor laser device 40 Bonding material 41 Wire

Claims (13)

In a semiconductor laser device in which a plurality of semiconductor laser chips are arranged on a substrate,
Some of the semiconductor laser chips are face-down mounted and face-up mounted.
A step is formed on the surface of the substrate, the semiconductor laser chip is mounted face-up on the step bottom of the substrate, and a semiconductor laser chip is mounted face-down on the step top of the substrate. A semiconductor laser device.   2. The semiconductor laser device according to claim 1, wherein the semiconductor laser chip mounted face up has a wider range of heat propagation to the substrate side than the semiconductor laser chip mounted face down. 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser chips are alternately arranged in a face-down manner and in a face-up manner. 4. 4. The semiconductor laser device according to claim 1, wherein adjacent semiconductor laser chips are electrically connected to each other. 5. The semiconductor laser device according to claim 1, wherein the semiconductor laser chip disposed at the end of the substrate is mounted face-up. 6. The semiconductor laser device according to claim 1, wherein the semiconductor laser chips disposed at both ends of the substrate are mounted face-up. 7. The semiconductor laser device according to claim 1, wherein the light emitting points of the semiconductor laser chips disposed on the substrate are at substantially the same height. 8. The semiconductor laser device according to claim 1, wherein a chip width of the semiconductor laser chip is narrower when face-down is mounted than when face-up is mounted. 9. 2. The semiconductor laser device according to claim 1, wherein the substrate includes a first substrate and a second substrate partially formed on the first substrate.   The semiconductor laser device according to claim 9, wherein the first substrate has higher thermal conductivity than the second substrate. In a method for manufacturing a semiconductor laser device in which a plurality of semiconductor laser chips are arranged on a substrate,
Preparing the semiconductor laser chip;
Preparing a substrate with a step formed on the surface;
Mounting the semiconductor laser chip face up on the step bottom of the substrate;
And a step of mounting the semiconductor laser chip face down on the stepped portion of the substrate. 12. The semiconductor laser device according to claim 11, wherein the semiconductor laser chip mounted face up and the semiconductor laser chip mounted face down are mounted so as to be alternately arranged on the substrate. Production method. After the semiconductor laser chip mounting step, it comprises a step of wire bonding so as to electrically connect adjacent face-down mounted semiconductor laser chips and face-up mounted semiconductor laser chips. A method of manufacturing a semiconductor laser device according to claim 11.

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