JP2004138971A - Package for optical waveguide type module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package with which the uniformity of the temperature of a chip in an optical waveguide type module, the reduction of the stress to be exerted on the chip and the reduction of the electric power consumption of a heating means for heating the chip can be achieved. <P>SOLUTION: The optical waveguide type module includes the chip 20 formed with a waveguide, an aluminum heater 24 for heating the chip, and a highly thermally-conductive material 26, such as a Cu-W alloy, interposed between the chip and the heater in such a manner that the heat of the heater is evenly distributed and conducted to the chip. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a package for an optical waveguide type module that supports a device having an optical waveguide formed on a substrate (hereinafter referred to as a chip), and more particularly, to an arrayed waveguide grating (AWG) optical wavelength multiplexing / demultiplexing. The present invention relates to a structure of a package for a circuit module.
[0002]
2. Description of the Related Art In an optical communication system using an optical fiber as a transmission medium, an optical wavelength division multiplexing (optical WDM) technique for multiplexing and transmitting a plurality of optical signals having different wavelengths to one optical fiber is adopted. The present invention relates to a package for an AWG optical multiplexer / demultiplexer module most widely used among such optical WDMs. The AWG optical multiplexer / demultiplexer module multiplexes and transmits a plurality of optical signals having different wavelengths to one fiber, and demultiplexes the multiplexed optical signal for each wavelength component.
[0003]
[Prior art]
Waveguide-type modules have been widely used with an increase in the amount of communication in optical communication. A package used to manufacture this type of optical waveguide module is a structure that conventionally supports a device (chip) in which a glass waveguide is formed on a substrate made of silicon or quartz on an inner wall of the package. In order to exhibit the optical characteristics determined at the time of design, it is necessary to satisfy the following conditions.
(1) Temperature uniformity of the chip. Particularly, in the optical circuit forming portion of the chip, temperature uniformity of about ± several degrees C or less is required.
(2) No stress is applied to the optical waveguide portion of the chip. The stress applied to the waveguide portion is required to be several MPa or less.
(3) Low power consumption. The temperature uniformity of the chip is realized by heating with a heater. In this case, the power consumption of the heater is required to be several W or less.
[0004]
Incidentally, the waveguide type optical multiplexer / demultiplexer disclosed in Patent Document 1 as a related prior art is intended to simplify the circuit configuration, improve the yield, and alleviate the tolerance of manufacturing slabs. The end face formation positions facing each other between the output waveguides connected to the waveguides, or the end face formation positions facing the input waveguides connected to the respective slab waveguides are shifted so as not to overlap with each other.
[0005]
Further, in the method of manufacturing a planar optical waveguide disclosed in Patent Document 2, a step of forming a lower coating layer on a substrate in order to obtain a more precise optical element with a uniform effective refractive index in the optical waveguide. Further, it has been proposed to increase the uniformity of the thickness of the optical waveguide by adding a step of polishing the surface in each step such as a step of forming a core layer.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-71977 [Patent Document 2]
JP-A-11-72637
[Problems to be solved by the invention]
According to the structure of the conventional package for an optical waveguide type module, it cannot be said that the uniformity of the temperature of the chip, the reduction of the stress applied to the chip, and the low power consumption of the heating means for heating the chip are not sufficient.
[0008]
Therefore, the present invention provides an optical waveguide module for an optical waveguide module that can achieve a uniform temperature of a chip, a reduction in stress applied to the chip, and a reduction in power consumption of a heating unit for heating the chip. The task is to provide a package.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, according to the present invention, a chip having a waveguide formed thereon, a heater for heating the chip, and a high heat interposed for uniformly distributing heat of the heater and transmitting the heat to the chip. A package for an optical waveguide module, comprising: a conductive material;
[0010]
The high thermal conductive material is interposed between the chip and the heater. In this case, the high heat conductive material is planar, one surface of the material is bonded to the chip via an adhesive, and the other surface of the material is bonded to the heater via an adhesive. The contact area of the high heat conductive material on the chip side is smaller than the area of the chip on the high heat conductive material side.
[0011]
The chip is a silicon chip having a glass waveguide formed on silicon, the heater is a heater made of alumina, and the high thermal conductive material is a Cu-W alloy.
[0012]
It is also possible to arrange the heater adjacent to the chip and connect the high thermal conductivity material to the side of the heater opposite to the chip.
[0013]
Further, according to the present invention, a chip on which a waveguide is formed, a heater for heating the chip, and a heater interposed between the chip and the heater for uniformly distributing heat of the heater to the chip. A package body supporting the core section; and a package body such that an air layer is defined between the heater and a bottom surface of the package body. Means for supporting the optical waveguide module.
[0014]
In this case, the means for supporting the core portion on the bottom surface of the package body includes legs provided between the heater and the bottom surface of the package body so as to reduce a contact area between the heater and the bottom surface of the package body. I do.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0016]
FIG. 1 shows an example of an optical multiplexing / demultiplexing system suitable for using the optical waveguide module package of the present invention. Reference numeral 1 denotes a light emitting unit which includes a plurality of laser diodes (LDs) and emits laser light signals having different wavelengths. Reference numeral 2 denotes a modulator that modulates an optical signal of each wavelength emitted by each laser diode (LD) and transmitted through an optical fiber. A multiplexing unit 3 multiplexes optical signals having different wavelengths emitted by a laser diode (LD) so that the signals can be transmitted through one optical fiber. Reference numeral 4 denotes an amplifier, which includes a coupler 4a, an isolator 4b, a filter 4c, an LD 4d for excitation, and the like. Reference numeral 5 denotes a demultiplexing unit, which demultiplexes optical signals of different wavelengths transmitted by one optical fiber into optical signals of respective wavelengths. Each optical signal that is split and transmitted by a plurality of optical fibers passes through a filter 6, a switch 7, and an attenuator (attenuator) 8, and is received by a light receiving element (photodiode) 9.
[0017]
FIG. 2 shows an arrayed waveguide grating (AWG) optical wavelength multiplexing / demultiplexing circuit (chip) 20 having a slab waveguide formed on a substrate. A plurality of glass waveguides 11 are formed in an array on a rectangular plate-shaped silicon or quartz substrate 10. Optical signals A having different wavelengths are respectively transmitted from optical fibers (not shown) and input to the plurality of waveguides 11 a on the substrate 10. The optical signal transmitted through each waveguide 11a is multiplexed by the grating 12 and multiplexed into two waveguides 11b and 11c. Further, the light is multiplexed by the grating 13 into one waveguide 11d. The multiplexed optical signal B is transmitted to an optical fiber (not shown).
[0018]
As described above, the package structure supporting this type of chip 20 is required to achieve temperature uniformity of the chip, not to apply stress to the optical waveguide portion of the chip, and to reduce power consumption. . In order to fulfill these requirements, an embodiment of the present invention will be described with reference to FIGS. In these figures, 20 is a chip, 22 is an adhesive, 24 is a heater made of alumina, and 26 is a high thermal conductive material.
[0019]
As a heater for ensuring the heat uniformity of the chip 20, a rectangular and flat alumina heater 24 is used. A commonly used tungsten (W) is used for the resistance circuit wired inside the heater 24. In this case, the heat uniformity, stress, and power consumption were all insufficient values for exhibiting optical characteristics.
[0020]
FIGS. 3 to 5 particularly show the thermal uniformity of the chip. FIG. 3 is a sectional view of a comparative example, FIG. 4 is a sectional view of a first embodiment, and FIG. 5 is a sectional view of a first embodiment. In the comparative example shown in FIG. 3, the heater 24 made of alumina is directly bonded to the chip 20 by the adhesive 22. As described above, the chip 20 has a slab waveguide formed on a substrate, and the substrate surface opposite to the waveguide forming surface of the chip 20 is directly bonded to an alumina heater 24 with an adhesive 22. .
[0021]
On the other hand, in the first embodiment shown in FIG. 4, a rectangular plate-like material (high thermal conductive material) 26 having high thermal conductivity is inserted between the chip 10 and the heater 24 made of alumina. That is, the adhesive 22 is bonded between the chip 10 and the high thermal conductive material 26 and between the high thermal conductive material 26 and the alumina heater 24. The flat material (high thermal conductivity material) 26 having high thermal conductivity is silicon, aluminum nitride, Cu—W alloy, Cu, or the like, and the thermal conductivity is preferably α> 150 W / m ° C. .
[0022]
As described above, by attaching the high heat conductive material 26 to the alumina heater 24, the heat capacity is increased and the heat on the heater side is totally equalized.
[0023]
In the second embodiment shown in FIG. 5, the high thermal conductive material 26 is not placed between the chip 20 and the alumina heater 24 as in the first embodiment, but on the opposite side of the alumina heater 24 from the chip 20. Are placed. That is, the heater 24 made of alumina is directly bonded to the chip 20 by the adhesive 22, and the high thermal conductive material 26 is attached to the back surface of the heater 24 made of alumina. Also in this case, the heat of the alumina heater 24 is equalized over the entire plane by the high thermal conductive material 26, so that the chip 20 can be evenly heated.
[0024]
FIGS. 6 and 7 show a structure in which stress is not particularly applied to the optical waveguide portion of the chip. FIG. 6 shows a comparative example, and FIG. 7 shows a third embodiment.
[0025]
In the comparative example shown in FIG. 6, a plate-shaped material (highly heat-conductive material) 26 having high heat conductivity is inserted between the chip 20 and the heater 24 made of alumina, and these are bonded to each other by the adhesive 22. However, the area of the rectangular joint surface of the chip 20, the area of the upper and lower surfaces of the rectangle of the high thermal conductive material 26, and the area of the alumina heater 24 on the rectangular joint surface side are substantially the same. And these three are joined to each other flush.
[0026]
On the other hand, in the third embodiment shown in FIG. 7, the area of the high heat conductive material 26 in the shape of a rectangular flat plate is relatively reduced. That is, the contact area of the high heat conductive material 26 on the chip 20 side is made smaller than the area of the chip 20 on the high heat conductive material 26 side.
[0027]
The stress originally applied to the chip 20 is generated when a material different from the coefficient of thermal expansion of the chip 20 is bonded to the chip 20. In this case, the generated stress increases as the difference between the coefficients of thermal expansion increases and as the contact area increases. However, the generated stress of the chip 20 is not determined solely by the relationship with the component to which the chip is bonded. Therefore, stress analysis including the peripheral portion of the chip and its contact area was performed, and the optimum configuration was examined. As a result, it has been found that it is not sufficient to simply use a component having a small thermal expansion coefficient difference with the chip 20 as a component to which the chip 20 is bonded. When a chip having a glass waveguide formed on silicon is used as a chip, and a heater made of alumina is used as a heater, the high thermal conductive material 26 inserted between the two has a coefficient of thermal expansion close to that of silicon. It has been found that the use of a Cu-W alloy having a relatively different coefficient of thermal expansion from silicon compared to the use of aluminum nitride results in a lower chip generated stress.
[0028]
Therefore, the contact area of the chip 20 is reduced from almost the entire area of the chip 20 to an area corresponding to the optical circuit forming portion C (FIG. 7) including the gratings 12 and 13 (FIG. 2) and the waveguide on the chip 20. The stress generated in the chip 20 is reduced.
[0029]
According to the simulation test, in the model after the contact area was reduced, the stress generated when aluminum nitride was changed to a Cu-W alloy as the high thermal conductive material was reduced to about 75%.
[0030]
On the other hand, when the contact area was reduced to about 1/3 and a Cu-W alloy was used as the high thermal conductive material 26, a simulation test showed that the generated stress was reduced to about 23%.
[0031]
Therefore, it is preferable to reduce the contact area from the entire area of the chip 20 to the formation area C of the optical circuit forming portion including the grating and the waveguide on the chip 20 and to use a Cu-W alloy as the high thermal conductive material 26. It turned out to be.
[0032]
FIGS. 8 and 9 are designed to reduce the power consumption of the heater 24 made of alumina. FIG. 8 shows a comparative example, and FIG. 9 shows a fourth embodiment. The structure including the chip 20 having the waveguide formed therein, the heater 24 made of alumina for heating the chip 20, and the high heat conductive material 26 interposed between the chip 20 and the heater 24 made of alumina is the third structure in FIG. This is the same as the embodiment. That is, the contact area between the chip 20 and the heater 24 made of alumina is made smaller than the area of the chip 20. The above part is referred to as a core part 30.
[0033]
In the comparative example shown in FIG. 8, in supporting and fixing the core portion 30 to the inner wall of the package 34, the core portion 30 is fixed to the inner wall surface 34a of the package 34 with the heater flange 32 interposed on the back surface of the heater 24 made of alumina. I was When the heater flange 32 was used, the volume of the air layer between the heater 24 made of alumina and the package inner wall surface 34a could not be sufficient, and a sufficient heat insulating effect could not be obtained.
[0034]
In order to reduce the power consumption of the alumina heater 24, it is necessary to enhance the heat insulating effect of the portion to be heated. Further, when selecting the material of the package structure and the components that support the core portion 30, it is preferable to change the direction to increase the thermal resistance around the heated portion.
[0035]
According to the fourth embodiment shown in FIG. 9, in order to support the core section 30 on the bottom surface of the package 34, the contact area with the inner wall 34a of the package 34 is reduced as much as possible, and the thermal resistance is high during that time. Preferably, an air layer 38 is interposed. For this reason, inner stays (projections or legs) 36 are provided at the four corners of the back surface of the heater 24 made of alumina, and an area (contact area) for interconnection between the back surface of the heater 24 made of alumina and the inner wall surface 34a of the package is provided. In other words, the space between the back surface of the heater 24 made of alumina and the inner wall surface 34a of the package 34 is secured to secure the capacity of the air layer 38 by limiting the inner stay portion only. . The air layer 38 has an effect of reducing power consumption of the heater 24 made of alumina by a heat insulating effect.
[0036]
According to the simulation test, the power consumption can be reduced to about 22% by securing the air layer 38 between the heater 24 made of alumina and the inner wall surface 34a of the package as described above. Further, by providing the protrusion 36 having a thickness (t) of 1 mm on the bottom surface of the package, a result was obtained in which an effect of reducing power consumption by about 20% to about 50% can be expected.
[0037]
Although the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, and various forms, modifications, and modifications may be made within the spirit and scope of the present invention. It is possible.
[0038]
【The invention's effect】
As described above, according to the present invention, in a package structure for supporting and fixing a chip having a waveguide formed on a substrate, temperature uniformity of the chip can be achieved, and stress is applied to the optical waveguide portion of the chip. Power consumption of the heater can be reduced.
[Brief description of the drawings]
FIG. 1 shows an example of an optical multiplexing / demultiplexing system suitable for using the optical waveguide module package of the present invention.
FIG. 2 shows an arrayed waveguide grating (AWG) optical wavelength multiplexing / demultiplexing circuit (chip) having a slab waveguide formed on a substrate.
FIG. 3 shows a comparative example for examining the thermal uniformity of a chip.
FIG. 4 shows a first embodiment of the present invention in which the temperature uniformity of a chip is considered.
FIG. 5 shows a second embodiment of the present invention in consideration of the heat uniformity of a chip.
FIG. 6 shows a comparative example for examining a reduction in stress of a chip.
FIG. 7 shows a third embodiment of the present invention in which stress reduction of a chip is considered.
FIG. 8 shows a comparative example in which reduction in power consumption of a heater is considered.
FIG. 9 shows a fourth embodiment of the present invention in which low power consumption of a heater is considered.
[Explanation of symbols]
Reference Signs List 20 chip 22 adhesive 24 heater 26 high heat conductive material 30 core 34 package 36 inner stay 38 air layer

Claims (7)

An optical waveguide type comprising: a chip on which a waveguide is formed; a heater for heating the chip; and a high thermal conductive material interposed for uniformly distributing the heat of the heater and transmitting the heat to the chip. Package for module. The optical waveguide module package according to claim 1, wherein the high thermal conductive material is interposed between the chip and the heater. The high heat conductive material is planar, and one surface of the material is bonded to the chip via an adhesive, and the other surface of the material is bonded to the heater via an adhesive. 3. The optical waveguide module package according to claim 2, wherein a contact area of the conductive material on the chip side is smaller than an area of the chip on the high thermal conductive material side. The chip according to any one of claims 1 to 3, wherein the chip is a silicon chip having a glass waveguide formed on silicon, the heater is a heater made of alumina, and the high thermal conductive material is a Cu-W alloy. The package for an optical waveguide module according to claim 1. The optical waveguide module package according to claim 1, wherein the heater is arranged adjacent to the chip, and the high thermal conductive material is connected to a side of the heater opposite to the chip. A chip on which a waveguide is formed, a heater for heating the chip, and a high thermal conductive material interposed between the chip and the heater to uniformly distribute heat of the heater to the chip, A core portion comprising:
A package body supporting the core portion;
Means for supporting the core portion on the package body such that an air layer is defined between the heater and the bottom surface of the package body;
A package for an optical waveguide module, comprising: The means for supporting the core portion on the bottom surface of the package body comprises legs provided between the heater and the bottom surface of the package body so as to reduce a contact area between the heater and the bottom surface of the package body. 4. The package for an optical waveguide module according to claim 1.

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