JPH09260539A - Sub-mounter and semiconductor device as well as manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the temperature rise of a chip element to be mounted, by forming an electronic element, and besides, raising heat radiation property. SOLUTION: An electronic element 5 is made in the section other than the chip element mounting position at the chip element mounting face of a silicon semiconductor substrate 1, and high heat conductive matter 2 higher in thermal conductivity than the silicon semiconductor substrate 1 is charged without space in the recess 16 provided in the position opposite to the chip element mounting position of the silicon semiconductor substrate 1 at the opposite face of the silicon substrate 1 from the chip element mounting face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submount device used for mounting a chip element such as a semiconductor laser chip, a semiconductor device in which the chip element is mounted on the submount device, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A semiconductor laser chip is a compact disk (CD) because it is small, operates at low voltage, and is highly efficient.
It is indispensable for optical sources such as optical discs and optical communication.
The volume of the oscillation region of this semiconductor laser chip is 0.1μ
Since it is very small, m × 5 μm × 250 μm, and a current of several tens mA needs to flow in this region, heat dissipation measures are very important. Moreover, since the threshold current value of the semiconductor laser chip increases as the temperature rises, if heat dissipation is poor, the temperature of the semiconductor laser chip rises, and as a result, the threshold current value increases and heat generation further increases. The positive feedback will stop the oscillation. Also,
It is generally estimated that when the temperature of the semiconductor laser chip rises by 10 degrees, the life of the semiconductor laser chip becomes half, and it is important to lower the temperature of the semiconductor laser chip as much as possible in order to extend the reliability.

FIG. 4 is a perspective view of a conventional semiconductor device in which a semiconductor laser chip is mounted on a silicon semiconductor substrate and mounted on a base. In FIG. 4, 11 is a base, 1
Reference numeral 2 is a lead provided so as to penetrate the base 11, 10 is a heat sink standing on one surface of the base 11, 8 is a silicon semiconductor substrate fixed to the heat sink 10, and 9 is a compound semiconductor mounted on the silicon semiconductor substrate 8. Are semiconductor laser chips, 5 are electronic elements such as photodiodes and transistors provided on the silicon semiconductor substrate 8, and 3 are
Is an electrode provided on the silicon semiconductor substrate 8 and 4 is a solder deposited on the electrode 3 to obtain an electrical connection to the semiconductor laser chip 9.

In a semiconductor device having a semiconductor laser chip as shown in FIG. 4, from the viewpoint of heat dissipation,
It is preferable that the oscillation region of the semiconductor laser chip, which is a chip element, is brought into contact with a material having as high thermal conductivity as possible, for example, a metal such as silver or copper, diamond, boron nitride, or silicon carbide. However, in reality, as shown in FIG. 4, a structure in which the semiconductor laser chip 9 is mounted on the silicon semiconductor substrate 8 is often used. This is called a submount device.

Thus, the reason why the silicon semiconductor substrate 8 is used as a submount device is that electronic elements such as photodiodes and transistors are made on the silicon semiconductor substrate 8 and the semiconductor laser chip 9 is mounted on the silicon semiconductor substrate 8. This makes hybrid integration possible. In this case, the heat generated in the oscillation region of the semiconductor laser chip 9 is transmitted through the silicon semiconductor substrate 8 and radiated. Another advantage of mounting on the silicon semiconductor substrate 8 is that silicon is a semiconductor, the difference in thermal expansion coefficient between silicon and the semiconductor laser chip 9 is small, and when mounting the semiconductor laser chip 9, Semiconductor laser chip 9 with different thermal expansion coefficient
It is possible to reduce the distortion of.

[0006]

In the above-mentioned conventional example, in order to manufacture an electronic element and to reduce the distortion of the chip element due to the difference in thermal expansion coefficient, the silicon semiconductor substrate 8 is used.
Although it is used as a submount device, since the thermal conductivity of silicon is 1/2 to 1/3 that of metals such as silver and copper, boron nitride, and silicon carbide, heat dissipation is poor and the chip element Temperature rises. Therefore, when the maximum temperature that can be operated is limited or the submount device is used to mount a semiconductor laser chip with poor temperature characteristics,
The temperature of the semiconductor laser chip may rise considerably, the threshold current of the semiconductor laser chip may rise, and the life may be significantly shortened. On the other hand, if another material having good thermal conductivity is used instead of silicon as the submount device 8 in the semiconductor device of FIG. 4, an electronic element cannot be manufactured or the chip element is distorted due to a difference in thermal expansion coefficient. Occurs and the characteristics of the chip element deteriorate. Further, even if an electronic element is not manufactured, there is a case where a substrate having a small difference in thermal expansion coefficient must be used as the submount device in order to alleviate distortion of the chip element due to the difference in thermal expansion coefficient.

A first object of the present invention is to provide a submount device capable of enhancing the heat dissipation even when the original thermal conductivity is low and suppressing the temperature rise of the mounted chip element to be small, and a method for manufacturing the submount device. Is to provide.
A second object of the present invention is to provide a submount device capable of forming an electronic element, improving heat dissipation even when the original thermal conductivity is low, and suppressing a temperature rise of a chip element to be mounted. It is to provide the manufacturing method.

A third object of the present invention is to form an electronic element, improve the heat dissipation even when the original thermal conductivity is low, and suppress the temperature rise of the mounted chip element. A semiconductor device and a method for manufacturing the same are provided.

[0009]

According to another aspect of the present invention, there is provided a submount device, wherein a substrate is provided in a recess provided at a position opposite to a chip element mounting position of the substrate on a surface opposite to the chip element mounting surface of the substrate. It is filled with high thermal conductivity material with high thermal conductivity. According to this configuration, the position opposite to the chip element mounting position of the substrate on the surface opposite to the chip element mounting surface of the substrate is replaced with the high thermal conductivity substance having higher thermal conductivity than the substrate, and thus the original thermal conductivity Even when the temperature is low, the heat dissipation characteristics are improved, the heat generated from the mounted chip element can be effectively released, and the temperature rise of the chip element can be suppressed.

A submount device according to a second aspect is the submount device according to the first aspect, wherein the substrate is a silicon semiconductor substrate, and the high thermal conductivity material is a metal such as silver, copper, aluminum or gold, or diamond, It is an electrically insulating substance such as boron nitride, silicon carbide or aluminum nitride. According to this configuration, the same operation as the submount device according to claim 1 is performed.

According to another aspect of the submount device of the present invention, an electronic element is formed on the chip element mounting surface of the semiconductor substrate, and the electronic element is opposed to the chip element mounting position of the semiconductor substrate on the surface of the semiconductor substrate opposite to the chip element mounting surface. A high thermal conductivity material having a higher thermal conductivity than that of the semiconductor substrate is filled in the concave portion provided at the position. According to this configuration, the position of the surface of the semiconductor substrate opposite to the chip element mounting surface is opposed to the chip element mounting position of the semiconductor substrate is replaced with a high thermal conductivity material having a higher thermal conductivity than the semiconductor substrate. Even if the thermal conductivity is low, the heat dissipation characteristics are improved, the heat generated from the mounted chip element can be effectively released, and the temperature rise of the chip element can be suppressed to a small level. Moreover, since the electronic element is formed on the semiconductor substrate, the chip element and the electronic element can be hybridly integrated.

A submount device according to a fourth aspect is the submount device according to the third aspect, wherein the concave portion provided on the surface of the semiconductor substrate opposite to the chip element mounting surface is made to face the electronic element formation position. I have to. According to this configuration, when the electronic element generates a large amount of heat, it becomes possible to effectively release the heat generated from the electronic element,
It is possible to prevent the heat generated by the electronic element from adversely affecting the chip element.

The submount device according to claim 5 is the submount device according to claim 3 or 4, wherein
The semiconductor substrate is a silicon semiconductor substrate, and the high thermal conductivity material is a metal such as silver, copper, aluminum or gold, or an electrically insulating material such as diamond, boron nitride, silicon carbide or aluminum nitride. According to this configuration, the same operation as the submount device according to claim 3 or 4 is exerted.

According to a sixth aspect of the present invention, in a semiconductor device, an electronic element is formed on a chip element mounting surface of a semiconductor substrate, and the electronic element is formed on a surface of the semiconductor substrate opposite to the chip element mounting surface. A high thermal conductivity substance having a higher thermal conductivity than the semiconductor substrate is filled in the recess provided in the
The chip element is mounted at the chip element mounting position on the chip element mounting surface of the semiconductor substrate.

According to this structure, the position of the surface of the semiconductor substrate opposite to the chip element mounting surface opposite to the chip element mounting position of the semiconductor substrate is replaced with the high thermal conductivity material having a higher thermal conductivity than the semiconductor substrate. Even when the original thermal conductivity is low, the heat dissipation characteristics are improved, the heat generated from the mounted chip element can be effectively released, and the temperature rise of the chip element can be suppressed to a small level. Moreover, since the electronic element is formed on the semiconductor substrate, the chip element and the electronic element can be hybridly integrated.

According to a seventh aspect of the present invention, in the semiconductor device according to the sixth aspect, the concave portion provided on the surface of the semiconductor substrate opposite to the chip element mounting surface is made to face the electronic element formation position. There is. With this configuration, when the electronic element generates a large amount of heat, it is possible to effectively release the heat generated from the electronic element, and it is possible to prevent the heat generated by the electronic element from adversely affecting the chip element.

The semiconductor device according to claim 8 is the semiconductor device according to claim 6 or 7, wherein the semiconductor substrate is a silicon semiconductor substrate, and the high thermal conductivity material is silver, copper,
It is a metal such as aluminum or gold, or an electrically insulating substance such as diamond, boron nitride, silicon carbide or aluminum nitride. According to this structure, the semiconductor device operates similarly to the semiconductor device according to claim 6 or 7.

A semiconductor device according to a ninth aspect is the semiconductor device according to the sixth aspect.
In the semiconductor device according to claim 7 or 8, the chip element is a semiconductor laser chip and the electronic element is a photodiode. According to this structure, the semiconductor device operates in the same manner as the semiconductor device according to claim 6, claim 7, or claim 8.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a submount device, wherein a recess is provided on a surface of the substrate opposite to the chip element mounting surface, at a position facing the chip element mounting position of the substrate, and the recess is provided with heat from the substrate. Fill with high thermal conductivity material with high conductivity. According to this method, the position opposite to the chip element mounting position of the substrate on the surface opposite to the chip element mounting surface of the substrate is replaced with a high thermal conductivity material having a higher thermal conductivity than the substrate, so that the submount device is originally designed. Even if the thermal conductivity of the sub-mount is low, the heat dissipation characteristics of the submount device can be improved, the heat generated from the mounted chip element can be effectively released, and the temperature rise of the chip element can be suppressed to a small level. it can.

In the method of manufacturing a submount device according to claim 11, the chip element mounting surface of the semiconductor substrate is formed after the electronic element is formed on the chip element mounting surface of the semiconductor substrate by a process such as thermal oxidation, impurity diffusion, and metal deposition. A recess is provided on the surface on the opposite side to the chip element mounting position of the semiconductor substrate, and a high thermal conductivity substance having a higher thermal conductivity than that of the semiconductor substrate is filled in the recess.

According to this method, the position opposite to the chip element mounting position of the semiconductor substrate on the surface of the semiconductor substrate opposite to the chip element mounting surface is replaced with the high thermal conductivity substance having a higher thermal conductivity than the semiconductor substrate. , Even if the original heat conductivity of the submount device is low, the heat dissipation characteristics of the submount device are enhanced, and the heat generated from the chip element can be effectively released, and the temperature of the mounted chip element can be improved. The rise can be kept small. Further, since the electronic element is formed on the semiconductor substrate,
The chip element and the electronic element can be integrated in a hybrid.

According to a twelfth aspect of the present invention, in the submount device, after the electronic element is formed on the chip element mounting surface of the semiconductor substrate by a process such as thermal oxidation, impurity diffusion, and metal deposition, the side opposite to the chip element mounting surface of the semiconductor substrate. A recess is provided at a position facing the chip element mounting position of the semiconductor substrate on the surface of
A high thermal conductivity substance having a higher thermal conductivity than that of the semiconductor substrate is filled in the recess, and then the chip element is mounted at the chip element mounting position on the chip element mounting surface of the semiconductor substrate.

According to this method, the position of the surface of the semiconductor substrate opposite to the chip element mounting surface facing the chip element mounting position of the semiconductor substrate is replaced with the high thermal conductivity material having a higher thermal conductivity than the semiconductor substrate. Even if the original thermal conductivity of the semiconductor device is low, the heat dissipation characteristics of the semiconductor device can be improved, and the heat generated from the mounted chip element can be effectively released, and the temperature rise of the chip element can be prevented. It can be kept low. Moreover, since the electronic element is formed on the semiconductor substrate, the chip element and the electronic element can be hybridly integrated.

Table 1 shows the thermal conductivity of each substance. A substance having a thermal conductivity that is at least twice that of silicon is used immediately below a chip element such as a semiconductor laser chip, that is, on the side opposite to the chip element mounting surface of a semiconductor substrate. It is apparent that the heat conductivity of the mounting portion of the chip element is increased and the heat dissipation characteristics can be improved by arranging the surface of the semiconductor substrate at a position facing the mounting position of the chip element on the surface.

[0025]

[Table 1]

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG. FIG. 1A is a perspective view of the submount device according to the embodiment of the present invention, and FIG. 1B is a sectional view taken along the line AA ′ of FIG.
In this submount device, as shown in FIG. 1A, an electronic element 5 such as a photodiode or a transistor is formed on a silicon semiconductor substrate 1, and a semiconductor laser chip (not shown), which is a chip element, is mounted. An electrode 3 is formed at a mounting position (chip element mounting position on the chip element mounting surface), and patterned solder 4 is adhered thereon. It should be noted that a semiconductor laser chip mounted on a submount device (see FIG. 4) is called a semiconductor device.

The details of this submount device are as shown in FIG.
On the surface (chip element mounting surface) on which the semiconductor laser chip is mounted, the SiO ₂ film 6 is formed, the electrode 3 is formed thereon, and the solder 4 is further deposited thereon. On the other hand, there is, for example, a groove-shaped recess 16 on the surface of the silicon semiconductor substrate 1 opposite to the surface on which the semiconductor laser chip is mounted (chip element mounting surface). It is filled so that the surface becomes flat. Then, the electrode 7 is formed on the flattened surface. The recess 16 is provided at a position opposite to the surface (chip element mounting surface) on which the semiconductor laser chip is mounted and opposite to the semiconductor laser chip mounting position (chip element mounting position). The recess 16 is also provided at a position facing the position where the electronic element 5 is formed, and the heat can be effectively released even when the electronic element 5 generates a large amount of heat such as a transistor. As a result, it is possible to prevent the heat generation of the electronic element 5 from adversely affecting the semiconductor laser chip.

Next, a method of manufacturing this submount device will be described with reference to FIGS. 2 (a) to 2 (f). First,
The SiO ₂ film 14, the impurity diffusion region 13, and the metal electrode 15 by vapor deposition are formed on the silicon semiconductor substrate 1 by thermal oxidation to manufacture an electronic device or the like (FIGS. 2A and 2B). Next, the silicon semiconductor substrate 1 is polished to a predetermined thickness. Its thickness is 150 μm to 200 μm. The thinner the thickness of the silicon semiconductor substrate 1 is, the more advantageous it is for heat dissipation, but the silicon semiconductor substrate 1 becomes fragile and difficult to handle.

After polishing the silicon semiconductor substrate 1, a groove-shaped recess 16 is formed by etching. There are a chemical etching method and a dry etching method. If the remaining thickness of the silicon at the bottom of the recess 16 is as small as possible, the heat dissipation will be better, but the strength will be weakened and there is a risk of damage during the following process.
0 μm is left (FIG. 2 (c)).

After forming the concave portion 16, the high thermal conductivity substance 2 having a good thermal conductivity is filled into the concave portion 16. As the method therefor, thermal spraying, vacuum vapor deposition, vapor phase deposition method (C
VD method) and plating method. When metal is filled, thermal spraying, vapor deposition or plating is used, but in order to deposit only in the concave portion 16, a metal mask is used for thermal spraying or vapor deposition.
For plating, a mask may be used with a resist. In the case of plating, it is necessary to deposit a metal film in advance by vapor deposition.
A CVD method may be used to fill the insulator. CVD
Filling with diamond by the method is optimal for heat dissipation (FIG. 2 (d)). Fill the surface so that it is flat,
Electrodes 7 and solders 17 are formed to further mount the submount device on a package or the like (FIG. 2 (e),
(F)). The semiconductor laser chip is mounted after the submount device is completed, and the semiconductor device is completed.

FIG. 3 shows the current-light output characteristics of the semiconductor laser chip under the high temperature environment of 80 ° C. in the case of using the submount device of the embodiment of the present invention and the case of using the conventional submount device. Shows the difference. The curve A is the embodiment and the curve B is the conventional example. Copper was used as the material for filling the recesses. In the laser chip using the conventional submount device, the optical output is saturated at about 20 mW, whereas in the semiconductor laser chip using the submount device according to the embodiment of the present invention, an optical output close to 30 mW is obtained. You can see that it is being done.

In the above embodiment, the submount device is the silicon semiconductor substrate and the electronic element such as the photodiode is formed on the surface thereof. However, the electronic element need not be particularly formed. The present invention can be applied to a device in which a chip element is simply mounted on a substrate. Further, the chip element to be mounted on the submount device is not limited to the semiconductor laser chip, and any element can be mounted as long as the element generates a large amount of heat and the desired effect can be obtained. Further, if it is not necessary to build an electronic element in the submount device, it is not necessary to use a semiconductor substrate as a substrate, and the present invention can be applied to any substrate such as a ceramic substrate. Further, the electronic element is not limited to the photodiode or the transistor, and any element may be used. Further, if it is not necessary to expose the electronic element on the surface of the submount device, the chip element may be placed on the electronic element in a stacked manner.

[0033]

According to the present invention, the heat dissipation of the submount device can be improved, and the temperature rise of the chip element mounted on the submount device can be suppressed low. If this submount device is used for mounting the semiconductor laser chip, the semiconductor laser chip and the electronic element can be integrated in a hybrid, and the heat dissipation of the semiconductor laser chip is also excellent. In addition, even when integrated with a heat-generating electronic element such as a transistor, adverse effects on the semiconductor laser chip can be reduced. In particular, when the operating temperature is high or when the temperature characteristics of the semiconductor laser chip are not so good, a great effect is exerted on the reliability.

[Brief description of drawings]

FIG. 1A is a perspective view of a submount device according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA ′ of FIG.

2A to 2D are cross-sectional views in order of the processes, showing the manufacturing process of the submount device according to the embodiment of the invention.

FIG. 3 is a current-light output characteristic diagram of the semiconductor laser chip in the embodiment of the present invention and the conventional example.

FIG. 4 is a perspective view of a semiconductor device in which a semiconductor laser chip is mounted on a conventional submount device.

[Explanation of symbols]

1 Silicon Semiconductor Substrate 2 High Thermal Conductivity Material 3 Electrode 4 Solder 5 Electronic Element 6 SiO ₂ Film 7 Electrode 8 Silicon Semiconductor Substrate 9 Semiconductor Laser Chip 10 Heat Sink 11 Base 12 Lead 13 Impurity Diffusion Area 14 SiO ₂ Film 15 Electrode 16 Recess 17 Solder

Claims (12)

[Claims] 1. A high thermal conductivity substance having a higher thermal conductivity than that of the substrate is filled in a concave portion provided on a surface of the substrate opposite to the chip element mounting surface at a position facing the chip element mounting position of the substrate. A submount device characterized in that 2. The substrate is a silicon semiconductor substrate, and the high thermal conductivity material is a metal such as silver, copper, aluminum or gold, or an electrically insulating material such as diamond, boron nitride, silicon carbide or aluminum nitride. 1. The submount device according to 1. 3. An electronic element is formed on a chip element mounting surface of a semiconductor substrate, and a concave portion is provided on a surface of the semiconductor substrate opposite to the chip element mounting surface, at a position facing a chip element mounting position of the semiconductor substrate. A submount device characterized in that a high thermal conductivity substance having a higher thermal conductivity than that of the semiconductor substrate is filled therein. 4. The submount device according to claim 3, wherein the concave portion provided on the surface of the semiconductor substrate opposite to the surface on which the chip element is mounted is made to face the formation position of the electronic element. 5. The semiconductor substrate is a silicon semiconductor substrate, and the high thermal conductivity material is a metal such as silver, copper, aluminum or gold, or an electrically insulating material such as diamond, boron nitride, silicon carbide or aluminum nitride. The submount device according to claim 3 or 4. 6. An electronic element is formed on a chip element mounting surface of a semiconductor substrate, and a concave portion is provided on a surface of the semiconductor substrate opposite to the chip element mounting surface, at a position facing the chip element mounting position of the semiconductor substrate. A semiconductor device in which a high thermal conductivity substance having a higher thermal conductivity than that of the semiconductor substrate is filled therein, and a chip element is mounted at a chip element mounting position on a chip element mounting surface of the semiconductor substrate. 7. The semiconductor device according to claim 6, wherein the concave portion provided on the surface of the semiconductor substrate opposite to the surface on which the chip element is mounted is made to face the formation position of the electronic element. 8. The semiconductor substrate is a silicon semiconductor substrate, and the high thermal conductivity material is a metal such as silver, copper, aluminum or gold, or an electrically insulating material such as diamond, boron nitride, silicon carbide or aluminum nitride. The semiconductor device according to claim 6 or 7. 9. The semiconductor device according to claim 6, wherein the chip element is a semiconductor laser chip and the electronic element is a photodiode. 10. A high thermal conductivity substance having a thermal conductivity higher than that of the substrate in the concave portion at a position facing a chip element mounting position of the substrate on a surface of the substrate opposite to the chip element mounting surface. A method for manufacturing a submount device, comprising: 11. An electronic element is formed on a chip element mounting surface of a semiconductor substrate by a process such as thermal oxidation, impurity diffusion, and metal deposition, and then the semiconductor substrate on the surface opposite to the chip element mounting surface of the semiconductor substrate. A method for manufacturing a submount device, characterized in that a recess is provided at a position facing a chip element mounting position, and the recess is filled with a high thermal conductivity substance having a higher thermal conductivity than that of the semiconductor substrate. 12. After forming an electronic element on the chip element mounting surface of the semiconductor substrate by a process such as thermal oxidation, impurity diffusion, metal deposition, etc., the semiconductor substrate on the surface opposite to the chip element mounting surface of the semiconductor substrate. A concave portion is provided at a position facing the chip element mounting position, and the concave portion is filled with a high thermal conductivity substance having a higher thermal conductivity than the semiconductor substrate, and then at the chip element mounting position on the chip element mounting surface of the semiconductor substrate. A method of manufacturing a semiconductor device, comprising mounting a chip element.