JP2000208855A - Method and device for mounting optical semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mounting on a base substrate with high precision without being influenced by a melting condition of solder by melting solder under a condition where an optical semiconductor element is held with a chuck. SOLUTION: An optical semiconductor element 1 is positioned over a base substrate 3 and solder 2, and the optical semiconductor element 1 is applied as load, to an optical semiconductor element chuck 14 holding the optical semiconductor element 1, pressed against the base substrate 3 with uniform load with the solder 2 in between. Light is projected as heating light from a heating emission lens 31 provided below the base substrate 3, and transmitted through a base heating aperture 23 formed of quartz glass and a base absorption part 21, and supplied to the base substrate 3, to melt solder 2. As a result, a method for mounting onto the base substrate 3 with high precision without being influenced by a melting condition of the solder 2 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an optical semiconductor device, and more particularly to a method for bonding an optical semiconductor device used in an optical communication field or the like to a base substrate.

[0002]

2. Description of the Related Art In recent years, cost reduction has been desired in the field of optical communication in order to expand information service networks. Above all, in order to construct an optical communication system at low cost, there is a problem of reducing the cost of an optical module that converts an optical signal and an electric signal. In order to achieve this object, an optical module that can integrate optical components with high precision by a simple mounting method on the same substrate is required.

Optical components such as semiconductor laser diodes, edge-illuminated semiconductor light receiving elements, and optical switches are generally
Light enters and exits in a direction parallel to the plane of the substrate. In particular,
Optical semiconductor devices typified by edge-illuminated semiconductor laser diodes and semiconductor light-receiving devices are optical modules in which the positional relationship between the incoming and outgoing positions of light from optical devices and the light-emitting surface and light-receiving surface of the optical semiconductor device is assembled. Greatly affects the input and output of Therefore, conventionally, the solder bump method (Japanese Unexamined Patent Publication No.
No. 49) or a thin-film solder reflow method (JP-A-9-542).
No. 29), the optical semiconductor element was fixed on the substrate by controlling the position of the optical semiconductor element before the solder was melted.

[0004]

In the prior art described above, when mounting an edge-illuminated type optical semiconductor element on an optical module, the solder is melted under no load, so that the thickness of the solder layer after solder melting and the components to be mounted are reduced. Is difficult to control.
In addition, when the solder is melted in an unconstrained state, component movement occurs due to the self-alignment effect of the solder. However, depending on the cleavage accuracy when the optical component is chipped from the wafer, the self-alignment effect may deteriorate the accuracy. It works, and the displacement at that time cannot be ignored.

SUMMARY OF THE INVENTION It is an object of the present invention to restrain the position of an optical element when mounting an optical semiconductor element on a base substrate, even if the solder used for connection is molten, to thereby achieve the thickness and posture of the solder. And a method and apparatus for controlling the horizontal position and the vertical direction with high accuracy.

[0006]

According to the present invention, in order to solve the above-mentioned problems, in mounting an optical semiconductor device as an optical component and a base substrate, the solder is melted while holding the optical semiconductor device with a chuck. Accordingly, it is an object of the present invention to realize a highly accurate mounting method on a base substrate which is not affected by the molten state of the solder. Therefore, an optical semiconductor element chuck provided with a window for grasping the optical semiconductor element and observing its position from above, a load detector capable of accurately detecting a load applied to the optical semiconductor element chuck, and an optical semiconductor element are mounted. An optical device fixing section for fixing an optical device as a target, a heating device for melting solder between the optical semiconductor element and the optical device to fix them, and a position observation for observing a relative position between the optical semiconductor element and the optical device. Part, an optical semiconductor element,
Provided is an apparatus including a position adjustment unit that adjusts a positional relationship between optical devices.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for mounting an optical semiconductor device according to the present invention and an apparatus using the mounting method will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of an embodiment of the present invention. Optical semiconductor element chuck 14 that moves up and down
Is an optical semiconductor element adsorption section 11 made of quartz glass (linear expansion coefficient: 1.0 × 10 ⁻⁶ K ⁻¹ , thermal conductivity: 10 W / m · K);
An optical semiconductor element observation window 13 through which the position of the optical semiconductor element 1 can be observed from above is provided, and a space between the optical semiconductor element adsorption portion 11 and the optical semiconductor element observation window 13 is formed inside the optical semiconductor element adsorption hole 12 through the optical semiconductor element adsorption hole 12. By sucking air and lowering the internal air pressure below the atmospheric pressure, the optical semiconductor element 1 as one of the optical components can be adsorbed.

The base substrate suction table 24 for fixing the base substrate 3 is provided on the base substrate 3 on which the optical semiconductor element 1 is mounted.
And a heating light 34 from the heating light emitting lens 31.
There is provided a base heating window 23 for transmitting light.

The solder 2 for connecting the optical semiconductor element 1 and the base substrate 3 is vapor-deposited on the connection side of the optical semiconductor element 1 or the base substrate 3 or a pellet is provided between the optical semiconductor element 1 and the base substrate 3. The solder 2 is supplied by mechanically sandwiching the solder 2. Next, a method of fixing the optical semiconductor element 1 and the base substrate 3 with the solder 2 will be described step by step according to actual steps.

The optical semiconductor device 1 positioned on the base substrate 3 and the solder 2 applies the load at the time of mounting to the optical semiconductor device chuck 14 holding the optical semiconductor device 1 so that the solder 2 is mounted. Through the base substrate 3 with a constant load. The heat energy for melting the solder 2 is emitted as heating light 34 from a heating emission lens 31 provided below the base substrate 3, and passes through a base heating window 23 and a base suction part 21 made of quartz glass, It is supplied to the base substrate 3.

Here, the heating light 3 applied to the base substrate 3
Reference numeral 4 denotes that the material of the base substrate 3 is made of a material having a low reflectance of the wavelength of the supplied heating light 34, so that the light energy is effectively changed to heat energy, and the base substrate 3 is effectively heated. can do. The thermal energy that has heated the base substrate 3 is transferred to the optical semiconductor element 1, the optical semiconductor element suction section 11 and the base suction section 21 simultaneously with the heat transfer to the solder 2, which is the purpose of melting, and the position shift due to thermal expansion occurs. Cause.

Therefore, the optical semiconductor element adsorption section 11 and the base adsorption section 21 are provided with an optical semiconductor element adsorption hole 12 and a base adsorption hole 22 for fixing the optical semiconductor element 1 and the base substrate 3 at the respective center positions. Thus, the amount of heat due to the heat transfer is evenly spread to the optical semiconductor element suction part 11 and the base suction part 22, and the positional deviation due to thermal expansion can be reduced.

However, due to variations in conditions such as contact and heating, a slight temperature difference also remains in the adsorption portion, and the temperature difference causes a difference in thermal expansion, and a positional shift between the optical semiconductor element 1 and the base substrate 3. Cause.

Therefore, when a temperature difference occurs in the member, the optical semiconductor element suction unit 11 is used to keep the amount of positional deviation within the tolerance within tolerance (main required accuracy of optical parts ± 1 μm).
The base adsorbing portion 21 is made of a material having a linear expansion coefficient of 20 × 10 ⁻⁶ K ⁻¹ or less (for example, quartz glass, Pyrex, etc.) and the dimension is 10 mm × 10 mm or less. Is set, the positional deviation amount at the suction position when a temperature difference of 5 K occurs in the same member can be expressed by the following equation.

[0016]

20 × 10 ⁻⁶ (K ⁻¹ ) × 5 (K) × 5 (mm) = 0.0005 mm = 0.5 μm (Equation 1) of the optical semiconductor element suction unit 11 and the base suction unit 21 Considering the relative distance as the amount of displacement during mounting

[0017]

(Equation 2) 0.5 μm × 2 = 1 μm (Equation 2) This value is, for example, the base substrate 3 on which the fiber is mounted.
Even when the optical semiconductor element 1 is mounted thereon, the fiber and the optical semiconductor element 1 can be mounted with low coupling loss.

The heat energy applied to the optical semiconductor element 1 is transferred to the optical semiconductor element adsorption section 11 and the base adsorption section 21.
The temperature of the solder 2 depends on the amount of heat transfer. Therefore, by forming the optical semiconductor element adsorption section 11 and the base adsorption section 21 from a material having a thermal conductivity of 2 W / m · K or less, the amount of heat transferred to the optical semiconductor element adsorption section 11 and the base adsorption section 21 is reduced by the total heat quantity. 20% or less of
A change in the amount of heat transfer due to a contact thermal resistance or the like can be reduced, and stable connection between the optical semiconductor element 1 and the base substrate 3 can be ensured.

(Embodiment 2) FIG. 2 shows an example of an apparatus for mounting the optical semiconductor element 1 using the mounting method of Embodiment 1. The mounting apparatus vacuum-adsorbs the base substrate 3 to a base substrate adsorption table 24 having an adsorption portion made of quartz glass. At this time, the position of the base substrate 3 is adjusted so that the mounting position of the optical semiconductor element 1 on the base substrate 3 coincides with the center of the vacuum suction hole 22. Also, the optical semiconductor element 1 that is adsorbed by the optical semiconductor element chuck 14 is also vacuum-adsorbed so that the center position of the optical semiconductor element 1 and the relative position of the optical semiconductor element adsorption hole 12 coincide with each other. The semiconductor element is transported from the semiconductor element transfer section 44 to the space above the base substrate 3.

Optical semiconductor device 1 moved onto base substrate 3
Above the optical semiconductor element mounting position of the base substrate 3
It descends to μm and stops. The position of the optical semiconductor element 1 and the base substrate 3 is determined by setting the positioning marker previously attached to the optical semiconductor element 1 and the base substrate 3 to a low output.
Reference light including infrared light from the base substrate 3 is irradiated to the lower portion of the base substrate 3 by the fiber 32 and the heating light emitting lens 31,
The light passes through the base substrate 3 made of i or quartz, the optical semiconductor element 1 made of InP or the like, and is observed by the optical system 41 installed above the optical semiconductor element 1.

An image including the positioning markers of the optical semiconductor device 1 and the base substrate 3 is converted into position data by an image processing section 42 and sent to a host computer 43. The host computer 43 measures the relative position between the optical semiconductor element 1 and the base substrate 3 based on the transmitted position data, operates the base fine movement unit 26 to a normal mounting position, and positions the optical semiconductor element 1 and the base substrate 3. Do. By lowering the optical semiconductor element chuck 14, the positioned optical semiconductor element 1 is pressed against the base substrate 3 sandwiching the solder 2 to a load required for mounting.

Next, the solder 2 sandwiched between the optical semiconductor element 1 and the base substrate 3 is heated by the heating light 34 emitted from the heating light emitting lens 31 via the fiber 32 from the optical heating device 33 to the back surface of the base substrate 3. Is heated and melted by the heat transfer. Here, the thermal expansion in the thickness direction generated in the base substrate 3 by heating the base substrate 3 is such that the load displacement generated in the optical semiconductor element chuck 14 is monitored by the load meter 18 and the host computer 43 and always shows the same value. , It is possible to realize mounting with a constant load, that is, a stable solder height.

After the solder is melted, the optical heating device 33 is stopped, and the supply of the heating light 34 is stopped, so that the solder 2 is cooled, and the optical semiconductor element 1 and the base substrate 3 at a constant solder height are cooled. Measure the connection. After the cooled optical semiconductor element 1 is mounted on the base substrate 3, the vacuum suction of the optical semiconductor element chuck 14 is stopped, the optical semiconductor element chuck 14 is evacuated, and then removed from the base substrate suction table 34.

When a plurality of optical semiconductor elements 1 are mounted on the same base substrate, the first mounted optical semiconductor element 1 is replaced with a solder 2 having the highest melting temperature among the plurality of mounted optical semiconductor elements. By using the solder 2 having a lower melting temperature as the mounting order becomes later, it becomes possible to mount a plurality of optical semiconductor elements 1 on the same substrate.

(Embodiment 3) FIG. 3 shows an embodiment 3 in which a plurality of optical semiconductor elements 1 are mounted by the same solder. When a plurality of optical semiconductor elements 1 are mounted with the same solder 2 on the base substrate 3 made of a material having a high thermal conductivity, the optical semiconductor elements 1 are mounted in advance on the base adsorption portion 21 having a low thermal conductivity as in the first embodiment. It is difficult to newly mount the optical semiconductor element 1 without melting the solder 2 of the optical semiconductor element 4.

Therefore, in order to provide a temperature difference on the base substrate 3, a heat radiating material 26 made of a material having high thermal conductivity is provided on the lower surface other than the optical semiconductor element 1 to be heated, and heat energy is released to the heat radiating material 26. Thus, a large temperature difference can be provided in the base substrate 3.

(Embodiment 4) The positions of a plurality of optical semiconductor elements 1 to be mounted on one base substrate 3 are close to each other, and a necessary temperature distribution on the base substrate 3 by the heat radiating material of Embodiment 3 cannot be created. When the composition of the solder 2 to be mounted cannot be changed, a plurality of optical semiconductor elements can be mounted by the structure shown in FIG.

A preheater 16 is built in the optical semiconductor element chuck 14 which holds the optical semiconductor element 1 to be mounted, and the heat is preheated only to the optical semiconductor element 1 which is in contact with the heat conductor 17. Thus, it is possible to cause a temperature difference between the optical semiconductor element 4 not adsorbed and the optical semiconductor element 1 adsorbed on the optical semiconductor element chuck 14.

The absolute condition of the preheating here is the melting temperature of the solder or lower (for example, a temperature of 280 ° C. or lower in the case of AuSn eutectic solder). After that, by heating the base substrate 3 with the light from the heating light emitting lens 31, only the pre-heated optical semiconductor element 1 can be selected, and the solder 2 of the optical semiconductor element 1 can be melted. .

[0030]

According to the present invention, the optical semiconductor element can be positioned on the base substrate with high precision, and high optical coupling can be easily achieved without using an optical lens or the like. Therefore, by using the method and the apparatus of the present invention, it is possible to manufacture a low-cost optical module and an optical transmission device without taking a complicated mounting process.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an optical semiconductor device according to a first embodiment of the present invention.

FIG. 2 is an overall structural cross-sectional view showing an apparatus for actually manufacturing an optical semiconductor element according to a second embodiment of the present invention.

FIG. 3 is a sectional structural view of an optical semiconductor device according to a third embodiment of the present invention.

FIG. 4 is a sectional structural view of an optical semiconductor device according to a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical semiconductor element, 2 ... Solder, 3 ... Base board, 4 ... Mounted optical semiconductor element, 11 ... Optical semiconductor element adsorption part, 12
... Optical semiconductor element suction holes, 13 ... Optical semiconductor element observation window, 1
4 ... Optical semiconductor element chuck, 15 ... Vacuum pump, 16 ...
Preheating heater, 17: thermal conductor, 18: load cell, 21
... Base suction part, 22 ... Base suction hole, 23 ... Base heating window, 24 ... Base substrate suction table, 25 ... Base heat radiation part,
26: base fine movement part, 31: heating light emitting lens, 32 ...
Fiber, 33: light heating device, 34: heating light, 41: optical system, 42: image processing unit, 43: host computer,
44 ... Optical semiconductor element transfer section.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazumi Kawamoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Manufacturing Research Laboratory, Hitachi, Ltd. (72) Hiroyuki Ota 216, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Information and Communication Business (72) Inventor Shigefumi Kito 216 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in Hitachi, Ltd. Information and Communication Business 5F073 BA09 EA29 FA22 FA23

Claims (8)

[Claims] In a surface mounting step of fixing an optical semiconductor element on a base substrate, the optical semiconductor element to be connected and the base substrate are heated at a mounting temperature of 2 W / m · K or less.
It is sandwiched from above and below by a low-expansion heat-insulating material having a characteristic of a linear expansion coefficient of 20 × 10 ⁻⁶ K ⁻¹ or less, and the optical semiconductor element and the base substrate are heated by an indirect heating device, and the solder between the optical semiconductor element and the base substrate is heated. A method of mounting an optical semiconductor element, wherein the optical semiconductor element and the base substrate are connected by melting the optical semiconductor element. 2. The method for mounting an optical semiconductor device according to claim 1, wherein the low-expansion heat insulating material is quartz glass. 3. The method for mounting an optical semiconductor device according to claim 1, wherein the low expansion heat insulating material is Pyrex glass. 4. A method according to claim 1, wherein the indirect heating device is a heating device using a xenon short arc lamp. 5. The method of mounting an optical semiconductor device according to claim 1, wherein the indirect heating device according to claim 1 is a heating device using laser light. 6. A heat conductor for releasing a part of a given amount of heat to provide a temperature difference in the base substrate in a part of the low-expansion heat insulating material in contact with the base substrate according to claim 1. Mounting method of an optical semiconductor element. 7. A method for mounting an optical semiconductor device, wherein two types of heating devices, the indirect heating device according to claim 1 and a preheating device for directly heating the optical semiconductor device, are provided in the same device. 8. An optical semiconductor device made of the low-expansion heat insulating material according to claim 1, a jig for gripping upper and lower portions of the base substrate, an indirect heating device for indirectly heating the optical semiconductor device and the base substrate, An optical semiconductor device mounting device, comprising: a positioning device that adjusts a relative position between an optical semiconductor device and a base substrate; and a detection device that detects a relative position between the optical semiconductor device and the base substrate.