JPS59193082A - Light emitting semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To attain the reduction of the capacitance bycontriving to miniaturize a sub mount by a method wherein the titled device is constructed in such a manner that only a light emitting semiconductor element is mounted and fixed on the sub mount. CONSTITUTION:The sub mount 1 is fixed on a stem 3 made of a metal of a high thermal conductivity. A metallic layer 5 is formed on this sub mount 1. Besides, a semiconducror laser element 2 is fixed thereon by means of low melting point solder 6. Further, wires 8 and 9 are connected to the upper surface of the layer 5 and the element 2, respectively. Since only the element 2 is mounted on the sub mount 1 and the wire 8 is just fixed in such a manner, the mount 1 can be made small. As a result, the capacitance of the sub mount 1 reduces, and accordingly the modulation of long wavelength communication is enabled at a high speed.

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a light emitting semiconductor device. [Background Art] Light-emitting semiconductor devices are used as light-emitting sources for audio discs, video discs, optical communications, and the like. Conventionally, for example, as a light-emitting semiconductor device for audio discs, a semiconductor laser element (chip) is mounted on the inner surface of a copper post fixed to a copper stem, as shown in Nikkei Electronics, September 14, 1981, pages 138-151.
A structure is known in which the chip is fixed via a silicon or copper submount, and a metal cap is hermetically attached to the stem to seal the chip and the like. Also, when installing the chip on the submount, mount the chip so that the active layer (optical waveguide) that emits light is located on the submount side at a 1°C so-called junction. Many have a down structure. Junction
The reason why the down mounting structure is adopted is to efficiently dissipate the heat generated during the operation of the semiconductor laser element through the submount, thereby stabilizing the characteristics of the element. The structure of this junction down is, for example,
Publication No. 81.771 and Utility Model Application Publication No. 150270-150
As shown in the above publication, this method is also used in semiconductor laser devices for optical communication. However, if such a junction-down structure is adopted, the active layer that emits light (several μm from the chip surface)
The active layer (optical waveguide) is not visible on the surface of the chip because the active layer (formed on the inside) is disposed almost close to the submount. In this state, there is a drawback that it is difficult to align the optical axes of the optical fiber and the semiconductor laser element when assembling the original communication semiconductor laser device. Particularly when the optical waveguide is shipped as a stem and assembled into a desired package by the user, it is difficult to align the optical axis with other optical systems if the optical waveguide is not visible. Therefore, in order to not reduce the heat dissipation properties of the chip and to make the optical waveguide visible during assembly, the applicant has decided to mount the chip as shown in Figure 1. It has a so-called junction-up structure where the optical waveguide can be seen on the top surface of Sennogu 2 fixed on Mount 1. However, the distance between the junction (active layer) and the submount is
Since it is significantly longer than the down structure (the active layer that makes up the optical waveguide is located at a depth of about 3 μm from the surface of a chip with a thickness of 100 μm, for example), the length of the heat transfer path becomes larger. The submount is formed of a material with good thermal conductivity, such as silicon carbide (SiC), which is suitable for reducing thermal resistance. Since this SiC is insulating, it is not possible to take out the electrode from the bottom surface of the chip and connect it to the submount and stem as in the conventional case. Therefore, on stem 3, Pb-8
via solder 4 made of n-In.

[The submount 1 is fixed, and Cr and Au are deposited on the upper surface (upper surface hull) of the submount 1 in advance to form a metal layer 5. ) are fixed to the chip 2 and a gold piece 7 through a solder material 6 made of Pb-8n, and a wire 8 is placed on the gold piece 7.
By adopting a structure in which the electrodes are connected, the lower electrode of the tube 2 can be taken out. Further, a wire 9 is connected to the upper mold 5 poles of the chip 2 . The assembly into the package is performed by screwing using the mounting hole 10 of the stem, and then by wire bonding. This structure has the advantage that the optical waveguide can be seen as a single line on the surface of the chip 2 during optical axis alignment, making it easy and accurate to align the optical axis, but it also has the following drawbacks: This has been made clear by the inventor. (1) A high-speed long-wavelength semiconductor laser device performs modulation at high speed, but at this time, since the submount 1 is made of an insulator such as SiC, capacitance is generated, which adversely affects the modulation characteristics. For this reason, it is desirable that the submount 1 be as small as possible. However, in a structure in which the chip 2 and the metal piece 6 are placed and fixed on the submount, for example, the chip 2 and the metal piece 6 are rectangular bodies with length and width of about 300 to 400 μm. is length】μm
. The width is only about 0.5 μm, and the capacitance cannot be reduced. (2) Since the chip 2 is sensitive to heat, it cannot be heat-treated at a low temperature, and even during assembly, the temperature
The temperature cannot exceed 00°C. For this reason,
4. Solder material to attach Zabu mount) 1 to stem 3. Attach the chip 2 and the gold piece 6 to the submount 1, and use low melting point solder as the filler material 5. Further, this solder is previously applied to the stem 3 and the submount 1 by vapor deposition. First, the chip 2 and the gold piece 6 are fixed to the submount 1, and then this submount 1 is fixed to the stem 3. However, in this method, when fixing the sub mount 1 to the stem 3, the tip 2
Since the solder fixing the gold piece 6 to the submount 1 also melts, the chip 2 and the metal piece 6 may easily become misaligned. (3 (As mentioned in (1) above, the submount 1 is small at 1 μm in length and 0.5 μm in width, so
It is difficult to mechanically fix the m-shaped chip 2 and the gold piece 6. In addition, as mentioned in (2) above, the work of fixing the submount 1 to the stem 3 also requires that the entire submount 1 be held in place because the tip 2 and the gold piece 6 on the submount 1 are in a state where they are easy to move. It is also difficult to use an automatic machine to fix it to the stem 3, and these connection operations have to be done manually, which is poor workability. [Object of the Invention] An object of the present invention is to reduce the submount capacitance in a light emitting semiconductor device in which a semiconductor laser element is fixed to a stem via an insulating submount. Another object of the present invention is to provide a manufacturing method that is easy to manufacture and easy to automatically assemble in the manufacturing of a light emitting semiconductor device in which a semiconductor laser element is fixed to a stem via an insulating submount. The aim is to reduce costs. The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings. [Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows. By adopting a structure in which only the semiconductor laser element is placed and fixed on the insulating submount, the submount can be made smaller, and the capacitance can be reduced. In addition, the insulating submount has a high melting point of '4. A semiconductor laser element having a low melting point solder material applied to the lower surface thereof is fixed to the stem via a ferrule 2, and then fixed to a submount by applying heat to the low melting point solder material, and Since only the semiconductor laser element is fixed to the submount, the submount and the semiconductor laser element can be mechanically fixed in sequence. [Example 1] Fig. 2 is a perspective view showing a semiconductor laser element mounting structure according to an embodiment of the present invention, and Figs. 3(a) and 3(b) are explanatory diagrams similarly showing a manufacturing method of the semiconductor laser element mounting structure. It is. First, the semiconductor laser element mounting structure will be explained. As shown in FIG. 2, the upper surface of a rectangular plate-shaped stem 3 made of a metal with high thermal conductivity, such as copper (Cu), is coated with a high melting point brazing material 4, such as Au-8n (melting point: 380°C). A submount 1 made of a silicon car is fixed. Further, this submount 1 has a metal layer 5 formed by sequentially depositing Cr and Au to a thickness of about several tens of micrometers to about 1 μm over the entire upper surface (principal surface). On top of this is a low melting point brazing material 6, such as solder (Pb-8n; melting point 180°C).
), a semiconductor laser element (chip) 2 having Au-based electrodes on its upper and lower surfaces is fixed. Chip 2 (Ma 2nd
As shown by the two-dot chain line in the figure, the optical waveguide 11 is fixed in a so-called junction-up state so that it is located above, that is, on the side that is in contact with the main surface of the submount (on the opposite side).・In addition, the stem 3 has a mounting hole 10.
There are two. Next, a method for manufacturing such a chip mounting structure will be described from 1 to 1 with reference to FIGS. 3(a) and 3(b). As shown in figure (a), prepare stem 3 of CLI.
After that, a submount 1 made of SiC is prepared, and this submount is held on the stem 3 by vacuum suction using a vacuum suction tool 12. The submount 1 has a length of 1 μm and a width of 05 μm, and a metal film 5 is formed on the upper surface (principal surface) by sequentially depositing Cr and Au. Further, on the lower surface, a [6 melting point brazing material 4 made of All-Sn is preliminarily applied. Therefore, the submount 1 is positioned and fixed to the stem 3 by temporarily soaking in this high melting point brazing material 4. Next, a chip 2 having length and width of 300 and 400 μm is held by a vacuum suction tool 13 and positioned and supplied to a sub mount 1'' by a vacuum suction tool 13. The thousand knobs 2 each have Au-based electrodes on the upper and lower surfaces. Further, on the surface far from the optical waveguide 11, a low melting point brazing material (melting point 180°C) made of Pb-8n is applied in advance.
6 is adhered thereto, the chip 2 is fixed to the submount 1 by temporarily melting this low melting point brazing material 6. In addition,
The metal layer 5 on the submount 1 is provided over the entire area of the submount 1, forming a chip attachment part and also forming a wire attachment part used for wire attachment, which will be described later. Further, the metal layer 5 and the low melting point brazing material 6 are formed by vapor deposition when the chip 2 is to be formed. Such a chip mounting structure is shipped in this state and assembled into a desired package by the user. Then, wires 8 and 9 are connected to the metal layer 5 and the top surface of the chip 2, respectively. Further, the optical axis is aligned using the optical waveguide 11 that appears floating on the chinograph surface as a guide so that the tip of the optical fiber supported by the pancage faces the optical waveguide end of the chinograph 2. [Effects] (1) Since only the chip 2 is mounted on the submount 1 and only the wire 8 is fixed, the submount 1 can be made smaller than the structure shown in FIG. As a result, the capacity of the submount 1 is also reduced, making it possible to modulate long wavelength communication at high speed. (21 The submount 1 is fixed to the stem 3 with a high melting point brazing material 4, and the 1000 knob 2 is fixed to the submount 1 with a low melting point brazing material 6. Also, the fixation is also done with the stem 3 country submount) The chip 2 is fixed to the submount 1 after the chip 2 is fixed to the submount 1. Therefore, the chip 2 is
The chip 2 is not heated above 00'C and thermal deterioration of the chip 2 does not occur. (3) There is only one submount 1 and one thousand knob 2, and submount bonding and chip bonding are generally used for semiconductor device assembly because there are no other obstacles around the bonding when they are fixed. It is also possible to fix the device using a chip bonder or to automatically assemble it. (4) Since the submount 1 is made of SiC with high thermal conductivity, it effectively transfers the heat generated by the chip 2 to the stem 3.
to communicate. Therefore, the chip 2 is placed in the submount 1 with the junction up, which is above the optical waveguide 11.
It can be fixed to Therefore, the optical waveguide can be observed when aligning the optical axis with the optical fiber, which makes it possible to perform the optical axis alignment work accurately and in a short time. (5) The lower electrode of the chip 2 is taken out by the metal layer 5 and the wire 8 connected to the metal layer 5. Therefore, unlike the structure shown in FIG. 1, there is no need for a gold piece serving as a relay body, and the number of parts can be reduced. (6) In the structure shown in Fig. 1, the chip 2 and gold piece 7 are fixed to the submount 1, and then the submount 1 is fixed to the stem 3. It is necessary to heat a large submount or a submount to which a chip and a gold piece are fixed, and the heating time is long. In contrast, in the present invention, when fixing the submount 1 to the stem 3, the submount 1 and the stem 3 are heated, and the submount 1 of the chip 2 is heated.
Since the heating is the heating of the chip 2 and the submount 1, the heat capacity becomes small and the heating time can be shortened. Note that in this embodiment, the metal layer 5 is attached to the submount 1
It is also possible to have a pattern consisting of a chip attachment part, a wire attachment part, and a connecting part connecting these parts, rather than covering the entire main surface. [Embodiment 2] FIG. 4 shows a semiconductor device for optical communication according to another embodiment of the present invention.
(Laser diode device with optical fiber) is a partially cutaway plan view, Figure 5 is a cross-sectional view of the bath 5 taken along the ■-v line in Figure 4, and Figure 6 is also incorporated into an optical communication system. It is a schematic diagram showing an example. This laser diode device is assembled based on a stem 3 of a rectangular plate. That is, the stem 3 is formed by cutting one side of a rectangular metal plate to form a ring-shaped sealing wall 14 in the center, and by hollowing out the inside of the ring-shaped sealing wall 14 more deeply and forming a pedestal part in the center of the bottom surface. It forms 15. Then, on this pedestal part 15, Au
A laser diode chip (chip) 2 is fixed by a Pb-8n solder onto a submount 1 made of SiC having the same structure as in the previous embodiment and fixed by a Pb-3n solder. Furthermore, guide holes 16 and 17 are provided at both ends of the stem 3, respectively, and extend toward the output surface of the laser beam 2. A fiber guide 19 in which an optical fiber 18 is inserted and fixed in the center is fitted into one of the guide holes 16 and fixed to the stem 3 with silver solder 20. The tip of the optical fiber 18 faces one exit surface of the chip 2, and is configured to introduce laser light into the optical fiber 18. At this time, the tip of the optical fiber 18 is fixed to the pedestal part 15 of the stem 3 with a fixing material 21 such as resin or salter, and the light intake efficiency (optical coupling efficiency) to the optical fiber 18 is determined by tightening, temperature characteristics, and a vibration cylinder. ) is taken care not to fluctuate. In addition, in the case of a single mode fiber in which the core diameter of the optical fiber 18 is about 8 μmφ, in order to obtain a desired optical coupling efficiency that can withstand use, the relative optical axis alignment accuracy of the tip of the optical fiber 18 with respect to the chip 2 is, for example, as follows. Must be within ±0.2 to 0.3 μm. On the other hand, a monitor fiber 22 is inserted and fixed into the other guide hole 17. This monitor fiber 2
The tip of the chip 2 faces the other output surface of the chip 2, and is adapted to monitor the light intensity of the laser beam. Further, two leads 23 and 24 are arranged on the stem 3. A wire 9 with one end fixed to the upper electrode of the chip 2 is fixed to the inner end of one lead 23, and a wire 8 with one end fixed to the metal layer of the submount 1 is fixed to the inner end of the other lead 24. has been done. In addition, both leads 8°9 are stem 3
It penetrates the peripheral wall of the stem 3 and is fixed to the stem 3 via an insulator such as glass. Further, a plate-shaped cap 25 is airtightly attached to the upper surface of the ring-shaped sealing wall 14 by a boom weld, thereby airtightly sealing the chip 2 and the like. When such a laser diode device 26 is mounted on various types of equipment, it is fixed to a mounting plate with screws using the mounting holes 10 provided at the four corners of the stem 3. for example,
As an example of this implementation, there is an example of incorporating it into an optical communication system as shown in FIG. That is, the laser diode device 26 is fixed on a thermoelectric cooling device 29 fixed on the substrate 28 of the optical communication device 27. Also, this board 28
A laser drive circuit 30 for driving and controlling the laser diode device 26 is provided. Photo sensor 31 to monitor laser light intensity. A Peltier control circuit 32 is incorporated which controls the thermoelectric cooling device 29 so that the chip 2 always operates at a constant temperature. Further, the photosensor 31 inputs monitor information of the laser light intensity to the laser drive circuit 3o. Such an optical communication device 27 receives an analog signal 34 as a digital signal 35 via a modulator 33, and sends the optical signal to a receiver 36 using an optical fiber 18 as a transmission medium. In the receiver 36, the optical signal is converted into an electrical signal by a photoelectric conversion device 37 such as a silicon photodiode, and the signal is amplified by an amplifier circuit 38. Thereafter, the digital signal 34 is sent to a demodulator 39 to receive communication information as an analog signal 34. [Effects] (1) Sentsubu 2 is fixed to stem 3 via Submount 1 in the state of a junction amplifier. Therefore, when aligning the optical axis with the optical fiber 18, the optical axis can be aligned using the optical waveguide 11 visible on the chip surface as a guide, resulting in highly efficient optical axis alignment. High accuracy can be achieved. Therefore, more reliable communication is possible in the optical communication system. (2) For the reason mentioned in (1) above, since the light absorption efficiency of the optical fiber can be improved, information can be transmitted further than before with the same output (lengthening of the transmission path). (3) Since only the chip 2 is fixed on the submount 1, the submount 1 can be made smaller. As a result, capacity can be reduced and long wavelength communication can be modulated at both speeds. (4) The chip 2 is fixed to the submount 1 which is fixed to the stem 3 via a high melting point brazing material via a low melting point brazing material. For this reason, the chip 2 is not exposed to high heat exceeding 200''(1') during assembly, so no thermal deterioration of the chip occurs. 2 on the submount 1 one by one, automatic assembly becomes possible.The invention made by the present inventor has been specifically explained above based on the embodiments, but the present invention is based on the above embodiments. It goes without saying that the present invention is not limited to the above, and that various changes can be made without departing from the gist thereof. Although the present invention has been described with reference to the field of optical communication technology, the present invention is not limited thereto, and can be applied, for example, to a mounting technique for a thousand knobs having electrodes on at least the front and back surfaces.

[Brief explanation of drawings]

FIG. 1 is a front view showing a semiconductor laser device mounting structure already developed by the applicant, FIG. 2 is a perspective view showing a semiconductor laser device mounting structure according to an embodiment of the present invention, FIG. 3(a), b) is an explanatory diagram showing the manufacturing method of the semiconductor laser element mounting structure, FIG. 4 is a partially cutaway plan view of a semiconductor device for optical communication according to another embodiment, and FIG. FIG. 6 is a sectional view of the bath 5 taken along the V-V line, and FIG. 6 is a schematic diagram showing an example of incorporating the same into an optical communication system. 1. Sub mount, 2. Semiconductor laser element (chip), 3. Stem, 4. Solder material, 5. Metal layer, 6..
・Brazing material, 7... Gold piece, 8, 9... Wire, 10...
Mounting hole, 11... Optical waveguide, 12.13... Vacuum suction upper part, 14... Ring-shaped sealing wall, 15... Pedestal part, 1
6,1.7... Guide hole, 18... Optical fiber,
19...Fiber guide, 20...Silver wire, 21.
・Fixing material, 22...Monitor fiber, 23.24
...Lead, 25...Cap, 26...Laser diode device, 27...Optical communication device, 28...Substrate, 29...Thermoelectric cooling device, 30...Laser drive circuit, 31... ... Photosensor, 32 ... Peltier control circuit, 33 ... Modulator, 34 ... Analog signal,
35...Digital signal, 36...Receiver, 37...
Photoelectric equipment, 38...Amplification circuit, 39...Demodulator.

Claims (1)

[Scope of Claims] 1. A light emitting semiconductor device comprising a light emitting semiconductor element and a support supporting the light emitting semiconductor element, wherein the light emitting semiconductor element is fixed to a part of the main surface of the support. . A light emitting semiconductor device, characterized in that a metal wire is bonded in direct contact with the other part of the main surface of the support. 2. The light emitting semiconductor device according to claim 1, wherein the support is made of an electrically insulating material, and the light emitting semiconductor element is a semiconductor laser element. 3. A step of fixing a support for supporting the light emitting semiconductor element to the stem via a high melting point solder; a step of fixing the light emitting semiconductor element to a part of the main surface of the support via a low melting point solder; 1. A method for manufacturing a light emitting semiconductor device, comprising the step of bonding a metal wire to the other portion of the main surface of the support.