JP4121591B2 - Manufacturing method of semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor laser device using a laser chip, which does not cause mis-alignments during a die bonding process and can be prevented from being short-circuited and on one surface of which positive and negative electrodes are formed. SOLUTION: In a semiconductor laser device which is constituted by mounting a semiconductor laser chip 200, having a plurality of electrodes 203 and 204 on one surface on a mounting member 101 having conductive film patterns 102 and 103 facing opposite the electrodes 203 and 204 on its mounting surface, the electrodes 203 and 204 are respectively connected to their corresponding conductive film patterns 102 and 103 by soldering 104 and 105, and the laser chip 200 is fixed on the member 101 with an insulating material containing resin 106.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser chip, a method of manufacturing a semiconductor laser device composed of stacked on the mount member.
[0002]
[Prior art]
GaN-based semiconductors are attracting attention as materials for realizing light-emitting elements in the ultraviolet or green region, and among them, it is desired to put into practical use a semiconductor laser device that oscillates at a shorter wavelength than before. . A feature of GaN-based semiconductors is that sapphire, which is an insulator, is used for the substrate. Therefore, in a light-emitting element using such a semiconductor, both positive and negative electrodes are formed on the growth layer side, unlike before. Of course. Therefore, in the GaN-based semiconductor laser device, the growth layer side is down, that is, in order to perform junction down die bonding, it is different from the conventional semiconductor laser device in which only one electrode is formed on the growth layer side. A mount member having a configuration is required.
[0003]
FIG. 8 shows an example of such a technique disclosed in Japanese Patent Laid-Open No. 7-235729. In the figure, 1 is a submount substrate, 2 is a metal pattern provided on the mounting surface of the submount, 3 is solder, 4 is a GaN semiconductor laser chip body, and 5 is provided on the semiconductor growth layer side of the GaN semiconductor laser chip. In addition, positive and negative electrodes. In this example, an insulating submount is used, and a metal film pattern corresponding to each of the positive and negative electrodes of the semiconductor laser is provided on the upper surface of the submount, and each is bonded to the electrode by soldering, and junction-down die bonding Is realized.
[0004]
Here, die bonding is generally the following process. Usually, the solder is provided in advance on the submount. This is heated above the melting point, the laser chip aligned at a predetermined position is pressed against the melted solder, and then the solder is cooled and solidified. As a result, the laser chip and the submount are bonded with good thermal conductivity.
[0005]
[Problems to be solved by the invention]
However, in the semiconductor laser chip having positive and negative electrodes on one side as shown in the above prior art, as shown in FIG. 8, there is a portion that is not bonded between the positive and negative electrodes, and it is bonded to the submount in a bridge shape. It will be. This causes the following problems that could not occur in the conventional semiconductor laser chip in which only one electrode is formed on the growth layer side.
[0006]
In the die bonding process, when the molten solder is cooled, the solidification and alloying of the solder does not necessarily proceed uniformly in each part, so the volume change and surface tension of the solder part change from region to region. A complex force is applied to the bonding surface. As shown in FIG. 8, in the semiconductor laser device in which the bonding surface is divided on both the positive and negative sides, the balance of the force applied to each bonding surface is lost, so that the laser chip moves during cooling and misalignment occurs. Resulting in. Actually, according to the inventor's experimental knowledge, the probability of occurrence of misalignment in the semiconductor laser device shown in FIG. 8 is compared with that in the conventional semiconductor laser in which only one electrode is formed on the growth layer side. About 5 times higher. Such misalignment not only causes a problem in the optical characteristics of the semiconductor laser device, i.e., the laser beam emission direction, but also has a positive / negative electrode formed on one side. It also caused a problem of leakage.
The object of the present invention is to eliminate the above-mentioned problems in the prior art.
[0007]
[Means for Solving the Problems]
The inventions includes a semiconductor laser chip having a plurality of electrodes on one side, the conductive film pattern opposing the respective electrode mounting member having on the loading surface, in the manufacturing method of the semiconductor laser device configured by stacking The semiconductor laser chip, in which each electrode and the conductive film pattern opposite to the electrode are respectively joined by solder, is placed on the mount member via solder , and the solder misalignment by an insulator but in the process of solidifying the solder by cooling the state to the mount member and the semiconductor laser chip is molten, the said semiconductor laser chip and said mounting member including a thermosetting resins It is fixed so that it may prevent.
[0009]
Preferably, in the semiconductor laser chip mounting surface of the mount member, a concave portion is provided in a portion in contact with the insulator containing the resin.
[0010]
In this specification, the mount member means a component for directly mounting a semiconductor laser chip, for example, a submount for a semiconductor laser chip, or a direct mounting on a stem, a frame or a package without using a submount. In this case, it refers to this stem, frame or package itself.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
FIG. 1 is a schematic cross-sectional view showing a semiconductor laser device according to Embodiment 1 of the present invention. In the figure, 10 is a semiconductor laser device of the present embodiment, 100 is a submount, 101 is an insulating submount substrate, 102 is a positive side metal pattern, 103 is a negative side metal pattern, 104 and 105 are solders, and 106 is insulating. 200 is a GaN-based semiconductor laser chip, 201 is a sapphire substrate, 202 is a semiconductor growth layer, 203 is a positive electrode, and 204 is a negative electrode. As shown in the figure, the solder and the metal pattern on the submount loading surface are appropriately formed so as to be insulated from each other, thereby enabling the mounting of semiconductor laser elements having positive and negative electrodes on one side. The point is the same as in the prior art. However, the difference is that a resin 106 is provided between the solders.
[0012]
FIG. 2 is a sectional view showing the configuration of the GaN-based semiconductor laser chip in more detail, and the configuration will be described below with reference to this.
[0013]
On the surface of the sapphire substrate 201, a buffer layer 210 made of AlN or GaN, an n-GaN layer 211, an n-AlGaN cladding layer 212, a quantum well active layer 213 made of multi-layer InGaN, and a ridge stripe along the cavity direction of the semiconductor laser A p-AlGaN cladding layer 214 having a shape is sequentially formed. Further, an n-AlGaN current blocking layer 215 is further stacked outside the stripe, and a p-GaN cap layer 216 is stacked on the current blocking layer surface and the ridge stripe portion p-AlGaN cladding layer surface. A semiconductor growth layer 202 is constituted by the buffer layer 210 to the cap layer 216. A part of the semiconductor growth layer 202 is provided with a groove extending from the surface to the n-GaN layer in parallel with the ridge stripe, and each p-type growth layer is divided into two. On the surface of the p-GaN cap layer on the side where the ridge stripe exists, a positive electrode 203 is provided, and further, a negative electrode 204 is provided in contact with the n-GaN layer exposed at the bottom of the groove. It extends to the surface of the side p-GaN cap layer. As a result, the positive and negative electrodes are exposed on the growth layer side surface of the semiconductor laser chip.
[0014]
Further, an insulator 205 made of SiO ₂ or the like is provided inside the groove, and plays a role of preventing a short circuit in the die bonding process. With the above configuration, the stripe-shaped portion indicated by symbol 206 in FIG. 2 becomes the light emitting portion of the semiconductor laser. In the present embodiment, as an example, the size of the laser chip is set to length 0.5 × width 0.6 × height 0.1 mm, and the distance between the electrodes is 90 μm. Since such a semiconductor laser chip can be easily configured by a combination of known techniques, description of its manufacturing method is omitted.
[0015]
Next, a method for manufacturing the semiconductor laser device of the present embodiment will be described.
FIG. 3 is a diagram showing the submount 100 before the semiconductor laser chip 200 is loaded. Each symbol is the same as in FIG. As shown in this figure, prior to the die bonding step, resin 106 is applied on the submount loading surface in advance to form solders 104 and 105. In this embodiment, an epoxy resin that is thermosetting and has a curing temperature near the melting point of the solder is used as the resin. At this point, the resin 106 is uncured and has a certain degree of fluidity. In solder having a melting point of 156 ° C. is used for the solders 104 and 105, AlN as an insulator is used for the submount substrate 101, and Au (0.1 μm) / Pt (0. 1 μm) / Ti (0.1 μm) (Au on Pt on Ti, the same applies hereinafter). As an example, the size of the submount base 101 is set to length 1.5 × width 2.0 × height 0.2 mm, the distance between the solders is 100 μm, and the thickness of the solder is 1 μm. Each metal pattern and each solder can be formed by appropriately using known techniques such as vacuum deposition, CVD, sputtering, plating, thermal transfer, printing, and sintering.
[0016]
Such a submount was heated above the melting point of the solder to melt the solder. Subsequently, the semiconductor laser chip shown in FIG. 2 is appropriately aligned and loaded on the submount so that the laser chip electrode formation surface and the submount loading surface face each other. While applying the load, the temperature was held for about 1 minute. At this time, the upper end of the resin was in contact with the surface of the semiconductor laser chip. In this process, the resin 106 was gradually cured.
[0017]
Here, alignment is performed in the following manner. The positive electrode and the positive metal pattern, and the negative electrode and the negative metal pattern are bonded to each other, that is, as shown in FIG. 1, and the stripe direction of the semiconductor laser chip is aligned with the end face of the submount. The direction and the position are aligned so that the light emission surface substantially coincides with the end surface of the submount.
[0018]
Next, the submount and the entire semiconductor laser chip were cooled, and after applying the solder, the load was stopped. Thus, the die bonding process was completed, and the semiconductor laser device shown in FIG. 1 was completed.
[0019]
In the process of loading the chip, the resin 106 is not cured and is reasonably soft, so that the above-described process does not cause unnecessary distortion in the semiconductor laser chip, thereby deteriorating the characteristics of the completed semiconductor laser device. There is nothing.
[0020]
Further, in the cooling process, when the solder is solidified, the semiconductor laser chip is already appropriately fixed with the resin 106, so that the laser chip moves during the solder cooling, resulting in misalignment. Technical problems were avoided.
[0021]
For comparison, a target semiconductor laser device in which the resin 106 in the semiconductor laser device of this embodiment is omitted was manufactured. In the semiconductor laser device of this embodiment, when the laser beam center within ± 2 ° from the vertical direction of the end face of the submount is defined as a non-defective condition regarding the alignment in the die bonding process, the yield of non-defective products is 96. In contrast, the target semiconductor laser device was 70%. Thus, according to the present embodiment, the productivity of the semiconductor laser device is improved as compared with the conventional technique.
[0022]
Further, in the semiconductor light emitting device of this embodiment, the resin 106 is provided in almost the entire space between the solders as shown in FIG. 3, but as described above, the semiconductor laser is used during the die bonding process. For the purpose of fixing the chip and the submount, it is not always necessary to do this, and it may be provided only in a part thereof. Or it is not necessary to arrange | position resin so that it may be pinched | interposed into both positive and negative electrodes, and you may provide in the area | region of the end of a chip | tip. However, in the latter case, if the resin is arranged only on one side of the chip, the chip tends to be inclined and stacked, so that the resin amount is controlled more strictly or symmetrical on both sides of the chip. It may be necessary to devise such as placing resin on the surface. However, in the semiconductor laser device of the present embodiment, due to this configuration, during the die bonding process, the solder that is heated and melted and spread out comes into contact with the other solder, electrode, and metal pattern, resulting in a short circuit. There is also an effect of preventing the occurrence of.
[0023]
Furthermore, in the present embodiment, due to the presence of an insulator between the solders, the magnitude of the electric field between the solders is smaller than when there is no insulating resin when the semiconductor laser device is energized, Further, since the space between the solders is filled with resin, migration of the solder layer along the submount is less likely to occur, and the effect of improving the life characteristics of the semiconductor laser device is also achieved. In producing such an effect, as described above, unnecessary distortion does not occur in the semiconductor laser chip.
[0025]
[Embodiment 2]
FIG. 4 is a partial cross-sectional view showing the semiconductor laser device according to the second embodiment of the present invention, which corresponds to an enlarged portion in the vicinity of each solder in FIG. In the figure, 30 is the semiconductor laser device of the second embodiment, 300 is a submount, 301 is a groove, and other parts identical to those of the first embodiment are denoted by the same reference numerals. This embodiment is a modification of the first embodiment, and as shown in the drawing, except that a groove 301 is formed between the solders 104 and 105 on the loading surface of the submount. The same as in the first embodiment. In the present embodiment, the size of the groove is 30 μm wide and 100 μm deep. Such groove formation can be performed by appropriately selecting a known grooving technique such as scribing, dicing, wire saw processing, electric discharge processing, etching, sputtering, laser processing, FIB processing, and sandblast processing.
[0026]
FIG. 5 is a partial sectional view of a submount used in the semiconductor laser device of the present embodiment, and is an enlarged view of a portion corresponding to FIG. As shown in the figure, the submount is provided with a groove at the above-described location, and an insulating resin 106 is provided thereon. When this submount is used to load the semiconductor laser chip of FIG. 2 in the die bonding process similar to that of the first embodiment, the semiconductor laser device of FIG. 4 is completed.
[0027]
In the present embodiment, a part of the resin enters the groove 301 by pressing from above and below for connecting the submount and the semiconductor laser element by the die bonding process. As described above, since the resin escape is provided, distortion is introduced into the semiconductor laser chip by the die bonding process, as compared with the case of the first embodiment, and the semiconductor laser device has high performance. Contribute to
[0028]
Also in the present embodiment, as in the first embodiment, misalignment in the die bonding process, prevention of short circuit, and prevention of migration of solder during energization are realized.
[0029]
In this embodiment, the groove 301 provided for the escape of the resin does not have to be below the resin 106 in advance as shown in FIG. It is clear that the same result as above is obtained.
[0030]
In addition, in view of the above description, it is also clear that a recess having an arbitrary shape that can escape resin instead of the groove 301 has the same effect as the case where the groove is provided.
[0031]
Furthermore, even in the semiconductor light emitting device of the present embodiment, it is not always necessary to provide the resin in the space between the solders only for the purpose of fixing the semiconductor laser chip and the submount during the die bonding process. This is as described in the first embodiment.
[0032]
[Embodiment 3]
FIG. 6 is a partial cross-sectional view showing the semiconductor laser device according to the third embodiment of the present invention, and is an enlarged view of a portion corresponding to FIG. In the figure, reference numeral 40 denotes a semiconductor laser device according to the third embodiment, 400 denotes a submount, and other parts identical to those of the first embodiment are described with the same reference numerals.
[0033]
The present embodiment is a modification of the first embodiment. Next, differences will be described while explaining the method for manufacturing the semiconductor laser device of the present embodiment.
[0034]
FIG. 7 is a partial cross-sectional view showing a submount used in Embodiment 3 of the present invention. This figure shows a portion corresponding to FIG. In the figure, 401 is an insulating resin sphere, and a thermoplastic novolac resin is used. Such installation of the insulating resin sphere can be performed by applying a mixture of the sphere and the holding liquid. The size of the resin sphere can be set to 5 μm as an example. Using the submount 400 as described above, the semiconductor laser chip shown in FIG. 2 was loaded by a die bonding process similar to that of the first embodiment, and the semiconductor laser device shown in FIG. 6 was completed. In this die bonding process, the resin spheres are softened in the high temperature process, and further, the resin spheres are integrated by being pressed from above and below to connect the submount and the semiconductor laser element. Is filled. The semiconductor laser device similar to that of the first embodiment can be manufactured through such steps.
[0035]
Also in the present embodiment, as in the first embodiment, misalignment in the die bonding process, prevention of short circuit, and prevention of migration of solder during energization were realized.
[0036]
As apparent from the above description, the shape of the resin sphere does not necessarily need to be a perfect sphere, and can be changed as appropriate, such as a rectangular parallelepiped, a columnar body, and a complex tow shape. However, it can be changed as appropriate. Further, in the present embodiment, it is needless to say that a groove or a recess for allowing an excess portion of the resin to escape may be provided as in the second embodiment.
[0037]
In the semiconductor light emitting device of the present embodiment as well, it is not always necessary to provide resin in the space between the solders only for the purpose of fixing the semiconductor laser chip and the submount during the die bonding process. This is as described in the first embodiment.
[0038]
As described above, the configuration of the present invention has been described with a specific example, but the scope of the present invention is not limited to this, and of course, each component can be replaced with a material having the same application, A combination of other techniques can also be used.
[0039]
Above resins, epoxy resins, novolac resins, polyester resins, phenolic resins, polyurethane resins, silicone resins, polyamide resins may be used include polyimide resins, etc., as is their nature, using a thermosetting resins be able to. Further, a filler or the like may be mixed in the resin.
[0040]
The above-mentioned insulating submount substrate is composed of other insulating materials such as diamond, Si, SiC, cBN, BeO, Al ₂ O ₃ , and further, as represented by diamond / Si, SiO ₂ / Si It can be replaced with another insulating submount substrate having a laminated structure of each insulating material. In addition, the submount substrate does not necessarily need to be insulative, and a conductive submount substrate can be used after devising electrical insulation between the positive and negative metal patterns. As the conductive submount substrate, materials such as Si, Ge, SiC, Cu, CuW, and Mo, and a stacked structure of these substances can be used.
[0041]
The solder described above can be replaced with other metallic brazing materials such as Sn, Pb, InAl, SnAg, PbIn, PbSn, AuSn, AuSi, and AuGe.
[0042]
The above-described semiconductor laser chip is not limited to the specific example shown in FIG. 2, and other materials such as GaN, SiC, Si, and SiO ₂ / sapphire can be used as the substrate. For example, other materials such as an InGaAsP system, an InGaAlP system, an AlGaN system, and a CdZnSe system may be used as a material system for the growth layer. Alternatively, the semiconductor laser chip can be replaced with another light emitting element chip such as a high-power LED or a super luminescence diode.
[0043]
Further, in the submount of the above embodiment, the shape of each solder and each metal pattern is shown as a specific example in FIG. 3, but the present invention is not limited to this, and can be appropriately changed. . For example, the metal pattern is not necessarily provided so as to cover almost the entire surface of the submount. Alternatively, the metal pattern may be divided into three or more as in the case of using a so-called multi-beam semiconductor laser chip having a plurality of light emitting portions on the same semiconductor chip. Further, it is easy for those skilled in the art to provide a wire bonding pad portion and a mark for alignment during die bonding on the submount stacking surface. .
[0044]
Further, as is well known, various films can be interposed between the solder layer and the submount base. For example, a film for improving the adhesion between the submount and the solder, the submount, and the like. A film for preventing a reaction between solders, and a film for improving adhesion between these films or preventing oxidation may be appropriately laminated. Pt / Cr, Au / Mo, Au / Pt / Cr, Au / Mo / Ti, or the like can be used as the metal pattern Au / Pt / Ti described in the above embodiment. It is assumed that various films are interposed between the solder, the insulating film, the bonding pad, and the submount substrate for the same purpose.
[0045]
Furthermore, in the manufacturing method of the semiconductor laser device of the present invention shown in the above embodiment, the resin and the solder are provided in advance on the submount before the die bonding step. However, both or one of these is provided in advance. It is obvious that the semiconductor laser device of the present invention can be manufactured even if it is provided on the surface of the semiconductor laser chip.
[0046]
In each of the above-described embodiments, the case where the submount is used as the mount member has been described. However, the application of the present invention is not limited to this, and other mount members may be used. That is, it is obvious that in any mounting member, if the portion of the laser chip that is die-bonded has the same configuration as that of each of the above-described embodiments, the other mounting members can achieve the same effect as described above. . Therefore, when the laser chip is directly mounted on the stem, frame, or package without using the submount, the configuration of the present invention can be applied to the stem, frame, or package.
[0047]
【The invention's effect】
According to the present invention, the configuration described above prevents misalignment during the die bonding process and improves the productivity of a semiconductor laser device having predetermined optical characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a semiconductor laser device according to a first embodiment of the present invention.
FIG. 2 is a sectional view showing the semiconductor laser chip according to the first embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing a submount according to the first embodiment of the present invention.
FIG. 4 is a partial cross-sectional view showing a semiconductor laser device according to a second embodiment of the present invention.
FIG. 5 is a partial sectional view showing a submount according to a second embodiment of the present invention.
FIG. 6 is a partial cross-sectional view showing a semiconductor laser device according to a third embodiment of the present invention.
FIG. 7 is a partial sectional view showing a submount according to a third embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a conventional semiconductor laser device.
[Explanation of symbols]
10, 30, 40 Semiconductor laser device 100, 300, 400 Submount 101 Submount base 102 Positive side metal pattern 103 Negative side metal pattern 104, 105 Solder 106 Resin 200 Semiconductor laser chip 201 Substrate 202 Semiconductor growth layer 203 Positive electrode 204 Negative Electrode 301 Groove 401 Resin sphere

Claims (2)

A method of manufacturing a semiconductor laser device, wherein a semiconductor laser chip having a plurality of electrodes on one side is stacked on a mount member having a conductive film pattern facing the electrodes on the stacking surface. And the semiconductor laser chip arranged so that the conductive film pattern opposed thereto is bonded by solder, is placed on the mount member via the solder , and the solder is melted It was cooled state to the mount member and the semiconductor laser chip in the process of solidifying the solder, as is with the semiconductor laser chip and said mounting member to prevent misalignment by an insulator comprising a thermosetting resins A method of manufacturing a semiconductor laser device, wherein the semiconductor laser device is fixed.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein a concave portion is provided in a portion of the mount member in contact with the insulator including the resin on the semiconductor laser chip mounting surface.

Images