JP2005135933A - Method of manufacturing semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor laser which is superior in heat dissipation properties. <P>SOLUTION: A laser diode bar 11 composed of a plurality of elements that are arranged in parallel is pinched between a first heatsink 12 and a second heatsink 13 to assemble a semiconductor laser. The ends of the laser diode bar 11 are held by securing jigs 18, and then the laser diode bar 11, and the heatsinks 12 and 13 are aligned relative to each other. Thereafter, the laser diode 11 and the heat sinks 12 and 13 are heated simultaneously and are fixed together by pressure. Then, parts of the laser diode bar 11, protruding from the heatsinks 12 and 13, are cut off so as to make the laser diode bar 11 match with the width of the heatsinks 12 and 13. The laser diode bar 11 and the heatsinks 12 and 13 hardly get out of position, the curved part of the laser diode bar 11 is corrected, and the two bond surfaces can be made substantially in parallel with each other and improved in adhesion to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a semiconductor laser in which a semiconductor laser is assembled by bonding a heat sink for heat dissipation to a so-called laser diode bar formed by arranging a plurality of elements.

  The light emitting region of the semiconductor laser is currently expanded to a blue-violet short wavelength region, and is expected to be applied to optical communication, high density optical recording, or a display. While the light emitting area is expanded in this way, there are problems such as reduction in operating current, low noise, low cost, high output, high speed operation, and reliability during high temperature operation. There are still many issues that need to be improved in applied equipment. In particular, for problems related to heat generation, the use of semiconductor lasers in many fields is limited. This problem related to heat generation is related to a large amount of heat generated per unit area of the semiconductor laser, and heat circulation causes phenomena such as an increase in junction temperature and generation of stress. As the operating temperature of the junction increases, the light emission output, the light emission efficiency, the lifetime of the semiconductor laser, and the like decrease, and there is a problem that the wavelength of light generated from the semiconductor laser is lengthened.

  Since the wavelength of light generated from this semiconductor laser is a function of the junction temperature of the semiconductor laser, it is necessary to keep the junction temperature constant when a specific output is desired. For example, for every 3.5 ° to 4.0 ° C. difference in the junction temperature of an AlGaAs laser diode used to pump an Nd: YAG rod or slab, the wavelength is shifted by 1 nm. Therefore, it is necessary to control the bonding temperature to an appropriate temperature.

As a method for controlling the heat generation of the semiconductor laser that causes these problems, for example, a method in which the semiconductor laser is submounted on a base such as silicon (Si) and further joined to a heat sink is used. There is also a method in which a heat sink is joined to both n-type and p-type electrodes of a semiconductor laser to release the generated heat. In general, a laser diode bar, which is one of the components of a semiconductor laser, has a unique curved shape resulting from the formation process. As a method of bonding the curved semiconductor laser and the two heat sinks in close contact, a spacer is sandwiched between the two heat sinks, and a laser diode bar is arranged in the gap formed thereby, and the heat sink is coated in advance. A method of melting and joining a certain solder has been proposed (for example, Patent Document 1).
JP-A-11-340581

  However, when the heat sink is jointed to both the n-type and p-type electrodes of the laser diode bar by soldering simultaneously, the conventional method uses the laser diode bar to be relied on without relying on the laser diode bar to be joined. There were problems such as tilting and misalignment. Further, since the laser diode bar is curved, there is a problem that when the laser diode bar and the heat sink are joined, the amount of solder must be increased in order to improve solder adhesion. As a result, the efficiency of heat dissipation is reduced, and there is a problem that the heat dissipation effect of the heat sink cannot be maximized, which causes deterioration of the characteristics of the semiconductor laser.

  The present invention has been made in view of such problems, and its purpose is to be able to bond two heat sinks to a laser diode bar without causing positional deviation and to obtain good adhesion. An object of the present invention is to provide a method of manufacturing a semiconductor laser that can reduce the amount of solder and that can maximize the heat dissipation effect of a heat sink and prevent characteristic deterioration.

  A method of manufacturing a semiconductor laser according to the present invention includes a step of holding a laser diode bar when assembling a semiconductor laser by sandwiching a laser diode bar formed by arranging a plurality of elements between a pair of heat sinks, and a laser diode. A step of performing relative alignment between the bar and the heat sink, a step of simultaneously bonding the laser diode bar and the heat sink by heating and pressing, and a step of processing the laser diode bar into a predetermined shape. .

  In the semiconductor laser manufacturing method according to the present invention, after the laser diode bar is held by a fixing jig or the like, the laser diode bar and the heat sink are relatively aligned. After that, the laser diode bar and the heat sink are simultaneously heated and pressed and joined together, and then the laser diode bar is processed into a predetermined shape.

  According to the semiconductor laser manufacturing method of the present invention, when assembling a semiconductor laser by sandwiching the laser diode bar between a pair of heat sinks, the laser diode bar and the heat sink are held by holding the laser diode bar with a fixing jig or the like. After that, the laser diode bar and the heat sink were heated and pressure-bonded at the same time, so that the curved shape of the laser diode bar was corrected and the laser was not misaligned. The two joint surfaces between the diode bar and the pair of heat sinks can be made parallel to improve mutual adhesion and to reduce the joining material (solder amount). Further, since the two heat sinks can be heated and bonded at the same temperature, the work process is simplified.

  In particular, the width of the laser diode bar is made longer than the width of the heat sink, the laser diode bar is fixed using the protruding portion of the laser diode bar, and the width of the heat sink is increased in the subsequent semiconductor laser processing step. At the same time, by cutting off the protruding portion of the laser diode bar, the junction area can always be maximized, so that a semiconductor laser having better heat emission than the conventional semiconductor laser can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
1 to 3 show a semiconductor laser manufacturing method according to the first embodiment of the present invention. In the semiconductor laser 10 of the present embodiment, a first heat sink 12 and a second heat sink 13 are integrated on both surfaces of a laser diode bar 11, and the laser diode bar 11, the first heat sink 12 and the second heat sink 13 are integrated. Are joined via a solder layer 14.

  The laser diode bar 11 has a plurality of elements arranged in parallel on a substrate made of GaAs (gallium arsenide) or the like by a method such as MOCVD (Metal Organic Chemical Vapor Deposition). After sequentially stacking an n-type semiconductor layer, an active layer (light emitting layer), a p-type semiconductor layer, and a p-type contact layer, a p-type electrode is formed on the p-type contact layer and an n-type electrode is formed on the back surface of the substrate by vacuum evaporation or the like. Formed. The laser diode bar 11 has, for example, a rectangular shape with a thickness of about 100 μm and a depth of about 500 μm to 900 μm, and the length of the portion sandwiched between the first heat sink 12 and the second heat sink 13 is 10 mm. However, the laser diode bar 11 has such a length that it protrudes from the first heat sink 12 and the second heat sink 13 to the left and right by 1 mm to 2 mm before assembly.

  As shown in FIG. 3, the n-side electrode terminal 15 is connected to the first heat sink 12 by the same number of gold (Au) wires 16 as the number of elements, and the p-side electrode terminal 17 is similarly connected to the second heat sink 13. Has been.

  The first heat sink 12 and the second heat sink 13 are formed from a material having electrical and thermal conductivity, such as copper (Cu). The thermal conductivity is a characteristic necessary for releasing a large amount of intense heat emitted from the laser diode bar 11 and maintaining the laser diode bar 11 at an appropriate temperature, and the electrical conductivity is a characteristic that causes the current to flow into the laser diode. This is a characteristic necessary for efficient conduction to the bar 11.

  In the semiconductor laser 10 having such a configuration, the laser diode bar 11 is held and fixed using the fixing jig 18, and then the relative positions of the laser diode bar 11, the first heat sink 12 and the second heat sink 13 are compared. In this state, the laser diode bar 11 and the first heat sink 12 and the second heat sink 13 are pressure-bonded while being heated at the same time, and then the laser diode bar 11 is processed into a predetermined shape. Hereinafter, a more specific description will be given with reference to FIGS. 1 to 3.

  First, as shown in FIG. 1, the laser diode bar 11 is held and fixed by a fixing jig 18. The fixing jig 18 only needs to have a holding mechanism such as a vise, but the heat to be conducted through the first heat sink 12 and the second heat sink 13 is conducted through the jig itself. In order to prevent this and to increase the heating efficiency in the subsequent heating process, it is desirable that the material is formed of a material having a lower thermal conductivity than the heat sink (for example, tungsten carbide: WC). In order to further increase the heating efficiency, a heating mechanism may be added to the fixing jig 18. On the other hand, the first heat sink 12 and the second heat sink 13 are held by suction pins (not shown) or the like. Subsequently, the first heat sink 12 and the second heat sink 13 are aligned above and below the laser diode bar 11 using the laser diode bar 11 held by the fixing jig 18 as a reference for alignment.

  After the alignment, as shown in FIG. 2, the solder layer 14 is heated at a melting temperature, for example, about 230 ° C. or more and 250 ° C. or less, and the first heat sink 12 and the second heat sink are applied to the laser diode bar 11. 13 are simultaneously pressed and bonded by a pressure plate (not shown) or the like. At this time, since the heat conductivity of the fixing jig 18 is small as described above, the applied heat is effectively applied to the solder layer 14 without being released from the fixing jig 18.

  When the joining of the first heat sink 12 and the second heat sink 13 is completed, the protruding portion of the laser diode bar 11 held by the fixing jig 18 is cut out according to the heat sink width. At this time, when the thickness of the laser diode bar 11 is thin, the laser diode bar 11 can be excised without scribing, but when it is thick, it may be excised with scribing.

  Finally, as shown in FIG. 3, the laser diode 19 with the heat sink assembled in this way is disposed on the mounting substrate, and the first heat sink 12 and the n-side electrode terminal 15 are included in the laser diode bar 11. The same number of gold (Au) wires 16 are connected by wire bonding, and similarly, the p-side electrode terminal 17 and the second heat sink 13 are connected.

  As described above, in the present embodiment, after fixing the laser diode bar 11 by the fixing jig 18, the fixed laser diode bar 11 and the first heat sink 12 and the second heat sink 13 are simultaneously heated and pressed. Since the laser diode bar 11 is curved, the shape thereof is straightened even if the laser diode bar 11 is curved, and the laser diode bar 11, the first heat sink 12, and the second heat sink 13 These two joint surfaces become parallel. As a result, the adhesion between the laser diode bar 11 and the first heat sink 12 and the second heat sink 13 by the solder layer 14 is improved, and the amount of solder can be reduced.

  Furthermore, since the first heat sink 12 and the second heat sink 13 are bonded at the same time, the first heat sink 12 and the second heat sink 13 can be bonded by the solder layer 14 having the same melting temperature, so that the work process can be simplified. In addition, since the protruding portion of the laser diode bar 11 is cut out in accordance with the width of the heat sink in the processing step of the laser diode bar 11, the junction area can always be maximized and the adhesion is improved. . Further, a thin laser diode bar having a thickness of about 100 μm can be excised without scribing. As described above, it is possible to obtain a semiconductor laser excellent in heat release properties.

(Second Embodiment)
FIG. 4 is a sectional view showing a method for manufacturing a semiconductor laser according to the second embodiment of the present invention. Since the basic configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted. In the above embodiment, when the first heat sink 12 and the second heat sink 13 are joined to the laser diode bar 11, the laser diode bar 11 fixed by the fixing jig 18 is used as a reference for alignment. In the embodiment, the first heat sink 12 is set in advance at a predetermined position on the substrate 20, and the first heat sink 12 is used as a reference for alignment.

  That is, first, the laser diode bar 11 held by the fixing jig 18 is moved in the XY axis direction together with the fixing jig 18 so as to be aligned with the joint surface of the first heat sink 12. Next, the second heat sink 13 held by a suction pin or the like is aligned so as to overlap the first heat sink 12. After the alignment, as in the first embodiment, the first heat sink 12 and the second heat sink 13 are joined to the laser diode bar 11 by simultaneously heating and pressing.

  However, in this embodiment, since the back surface 12A of the first heat sink 12 is bonded to the substrate 20 in advance, the heating temperature needs to be lower than the melting temperature of the solder layer or the like used here. The steps after the joining step are the same as those in the first embodiment.

  As described above, in the present embodiment, the first heat sink 12 is fixed on the substrate 20 in advance, and the laser diode bar 11, the first heat sink 12, and the second heat sink 13 are connected by using this as a reference for alignment. Since bonding is performed, when a weight is applied from the second heat sink 13 side during this bonding, a drag having the same magnitude as the weight is applied to the laser diode bar 11 due to a reaction from the substrate 20 side. Therefore, the curved state of the laser diode bar 11 is corrected, and the joint surfaces can be made parallel to each other as in the first embodiment. Other functions and effects are the same as those of the first embodiment, and a description thereof will be omitted.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the heat sink material does not necessarily need to be copper (Cu), and iron (Fe) having high thermal conductivity may be used.

It is a figure showing the manufacturing method of the semiconductor laser which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the process following FIG. FIG. 3 is a plan view for explaining a process following the process in FIG. 2. It is a figure for demonstrating the manufacturing method of the semiconductor laser which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Semiconductor laser, 11 ... Laser diode bar, 12 ... 1st heat sink, 12A ... Back surface, 13 ... 2nd heat sink, 14 ... Solder layer, 15 ... N side electrode terminal, 16 ... Gold (Au) wire, 17 ... p Side electrode terminal, 18 ... Fixing jig, 19 ... Laser diode with heat sink, 20 ... Substrate

Claims (9)

A semiconductor laser manufacturing method for assembling a semiconductor laser by sandwiching a laser diode bar formed by arranging a plurality of elements between a pair of heat sinks,
Holding the laser diode bar;
Performing a relative alignment between the laser diode bar and the heat sink, and heating and press-bonding the laser diode bar and the heat sink simultaneously to bond each other;
And a step of processing the laser diode bar into a predetermined shape. 2. The method of manufacturing a semiconductor laser according to claim 1, wherein the width of the laser diode bar is made longer than the width of the heat sink, and the laser diode bar is fixed using a protruding portion of the laser diode bar. . The method of manufacturing a semiconductor laser according to claim 2, wherein the laser diode bar is fixed by holding the protruding portion with a fixing jig. The method for manufacturing a semiconductor laser according to claim 1, wherein the fixing jig is made of a material having a thermal conductivity smaller than that of the heat sink. 4. The semiconductor laser according to claim 3, wherein when the relative alignment between the laser diode bar and the heat sink is performed, the laser diode bar fixed by the fixing jig is used as a reference for alignment. 5. Production method. 4. The method of manufacturing a semiconductor laser according to claim 3, wherein, when the relative alignment between the laser diode bar and the heat sink is performed, one of the heat sinks is used as a reference for alignment. 5. The method of manufacturing a semiconductor laser according to claim 1, wherein when the laser diode bar and the heat sink are joined, the curved shape of the laser diode bar is straightened. 3. The semiconductor laser according to claim 2, wherein when the laser diode bar is processed into a predetermined shape, a protruding portion of the laser diode bar sandwiched between the heat sinks is cut out in accordance with a heat sink width. Production method. 3. When the laser diode bar is processed into a predetermined shape, the protruding portion of the laser diode bar sandwiched between the heat sinks is cut out by scribing according to the heat sink width. Semiconductor laser manufacturing method.

Images