JPH08139296A - Semiconductor substrate and semiconductor integrated circuit device using the same - Google Patents

Abstract

PURPOSE: To provide a semiconductor substrate of an SOI structure and a semiconductor integrated circuit device using the same in which the life of a connector at a solder bump connection is increased. CONSTITUTION: A semiconductor integrated circuit device comprises an element forming substrate 1 of a silicon wafer formed with an element, and a support substrate 2 for supporting the substrate 1 by laminating it to the substrate via an oxide film 6 formed by oxidizing the substrate 1 to form a semiconductor substrate 4 of an SOI structure, wherein the substrate 4 is mounted in a flip-chip to a mounting substrate 5 via a solder bump 3. The thickness of the substrate 2 is much thicker than that of the substrate 1, and further the substrate 2 is formed of a material having thermal expansion coefficient substantially equal to that of the material for forming the substrate 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate mounting technique, and more particularly to an SOI (Silicon On Insulator) structure semiconductor substrate flip-chip mounted via solder bumps and a semiconductor integrated circuit device using the same. It is a thing.

[0002]

2. Description of the Related Art The techniques described below are for studying the present invention,
The present invention was studied by the present inventors upon completion, and its outline is as follows.

When flip-chip mounting a semiconductor substrate via a solder bump, the following two methods have been put into practical use in order to ensure the reliability of the connection portion of the solder bump.

The first method is to mount the semiconductor substrate by using a material having a coefficient of thermal expansion substantially equal to that of silicon, which is a material of an element forming substrate constituting the semiconductor substrate, such as mullite ceramic or aluminum nitride. To form a mounting board.

Still another method is to form the mounting board using a material having a thermal expansion coefficient substantially equal to that of a component mounting board on which electronic components and the like are mounted, and to mount the mounting board and the semiconductor substrate. The space between and is reinforced by resin.

Incidentally, another method described above, that is, a technique of reinforcing the space between the mounting substrate and the semiconductor substrate with a resin is disclosed in JP-A-60-63951.

[0007]

However, in the first method of the above-mentioned technique, high reliability can be obtained in connection between the semiconductor substrate and the mounting substrate, but it is often used as a material for the component mounting substrate. The glass epoxy resin
Since the coefficient of thermal expansion is large, there is a problem that the connection reliability between the mounting board (semiconductor integrated circuit device) and the component mounting board decreases.

Further, in the other one method described above, there remains a problem in the adhesiveness between the resin and the semiconductor substrate, and between the resin and the mounting substrate, and it is further necessary to fill the resin without a gap. To be done.

Further, since the semiconductor substrate is fixed by the resin or the like, there is a problem that the semiconductor substrate cannot be replaced when a defect occurs.

Therefore, an object of the present invention is to provide a semiconductor substrate having an SOI structure for extending the life of a connection portion in solder bump connection and a semiconductor integrated circuit device using the same.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0012]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, the semiconductor substrate according to the present invention comprises an element formation substrate on which elements are formed, and a support substrate that supports the element formation substrate by bonding it to the element formation substrate. Is much thicker than the thickness of the element forming substrate.

Further, in the semiconductor substrate, the element forming substrate and the supporting substrate are bonded together via an oxide film.

The support substrate of the semiconductor substrate is made of alumina.

The semiconductor integrated circuit device according to the present invention comprises the semiconductor substrate and a mounting substrate connected to electrodes on an element forming substrate forming the semiconductor substrate via solder bumps, and the supporting substrate is It is formed of a material having a coefficient of thermal expansion substantially equal to that of the material forming the mounting board.

[0017]

According to the above-mentioned means, the semiconductor substrate is composed of the element forming substrate on which the element is formed, and the supporting substrate for supporting the element forming substrate by being bonded to the element forming substrate directly or through the oxide film. The thickness of the supporting substrate is much thicker than the thickness of the element forming substrate, so that the thermal expansion coefficient and elastic coefficient of the semiconductor substrate after bonding the element forming substrate and the supporting substrate It is possible to make the physical characteristic value close to the physical characteristic value of the supporting substrate.

Further, since the supporting substrate in the semiconductor integrated circuit device is formed of a material having a thermal expansion coefficient substantially equal to that of the material forming the mounting substrate, the supporting substrate and the mounting substrate are separated from each other. It is possible to extend the service life of the connection portion in the solder bump connection.
Also, the reliability of the connecting portion can be improved.

Since the physical characteristic values such as the thermal expansion coefficient and the elastic coefficient of the semiconductor substrate after the element forming substrate and the supporting substrate are bonded together can be made close to the physical characteristic values of the supporting substrate, It is possible to select a material having desired mechanical properties as the material of the supporting substrate.

As a result, a material having a large coefficient of thermal expansion can be used as the material of the supporting substrate.

Further, since it is not necessary to reinforce the semiconductor substrate and the mounting substrate with resin or the like, it is possible to mount the semiconductor substrate on a bare chip.

By using alumina for the supporting substrate, since alumina is a high melting point material, it is possible to withstand high heat in the diffusion process at the time of manufacturing a semiconductor substrate, and also alumina is used for the mounting substrate. As a result, the life of the solder bump connecting portion can be extended, and the reliability of the connecting portion can be improved.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing an embodiment of the structure of a semiconductor substrate and a semiconductor integrated circuit device using the same according to the present invention.

First, the semiconductor substrate of the first embodiment is a semiconductor substrate having an SOI structure, and its configuration will be described. The element forming substrate 1 which is a silicon wafer on which elements are formed and the element forming substrate 1 are oxidized. And a support substrate 2 that supports the element formation substrate 1 by bonding the element formation substrate 1 through the oxide film 6 thus formed,
Furthermore, in the semiconductor substrate 4 of the first embodiment, the thickness of the support substrate 2 that is a constituent member thereof is much thicker than the thickness of the element formation substrate 1.

Here, the element forming substrate 1 is, for example, a silicon wafer having a thickness of about 1 to 5 μm, on which elements or circuits are formed, and the electrodes 1a are formed on the circuit.
Are provided, and the solder bumps 3 are connected to the electrodes 1a when the semiconductor substrate 4 is flip-chip mounted.

The support substrate 2 has a thickness of 400, for example.
It has a melting point of about 800 μm and is formed of alumina, which is a high melting point material having a melting point of about 2050 ° C., and is bonded to the element forming substrate 1 through the oxide film 6 to support the element forming substrate 1.

Therefore, the support substrate 2 is much thicker than the element forming substrate 1.

Here, a method of bonding the element forming substrate 1 which is a silicon wafer and the supporting substrate 2 will be described.

First, since the supporting substrate 2 is made of alumina which is a sintered material, its surface is very uneven when viewed microscopically. Therefore, the support substrate 2
The surface to be bonded to the oxide film 6 is polished, and the surface to be bonded is mirror-finished.

Thereafter, the element forming substrate 1 is oxidized to form an oxide film 6 (SiO ₂ ) on the element forming substrate 1.

Further, the space between the oxide film 6 and the supporting substrate 2 is placed in a vacuum state and pressure is applied, so that they can be bonded together.

This is because the alumina forming the support substrate 2 contains SiO ₂ as a binder (binder) at the time of sintering, and this Si and the S of the oxide film 6 (SiO ₂ ) are contained.
i is tied together and pasted together.

Next, the structure of the semiconductor integrated circuit device according to the first embodiment will be described. The semiconductor integrated circuit device comprises an element formation substrate 1 and a support substrate 2 supporting the element formation substrate 1 with an oxide film 6 interposed therebetween. SOI structure semiconductor substrate 4
Is a semiconductor integrated circuit device using a semiconductor substrate 4,
The mounting substrate 5 is connected to the electrodes 1a on the element forming substrate 1 via solder bumps 3.

That is, the semiconductor substrate 4 is flip-chip mounted on the mounting substrate 5 via the solder bumps 3.

An electrode 5a is provided on the mounting substrate 5, and the solder bump 3 is connected to this electrode 5a.

Here, the mounting board 5 is made of alumina, for example. As a result, since the supporting substrate 2 is also made of alumina, the supporting substrate 2 has a coefficient of thermal expansion substantially equal to that of the material forming the mounting substrate 5 (in the first embodiment, both are made of alumina. Therefore, the two materials have the same thermal expansion coefficient).

The operation and effect of the semiconductor substrate and the semiconductor integrated circuit device using the same according to the first embodiment will be described.

First, the element formation substrate 1 on which elements are formed
And a support substrate 2 that supports the element formation substrate 1 by being bonded to the element formation substrate 1 via an oxide film 6, and the thickness (about 400 to 800 μm) of the support substrate 2 is the element. Since it is much thicker than the thickness (about 1 to 5 μm) of the formation substrate 1, physical characteristics such as a thermal expansion coefficient and an elastic coefficient of the semiconductor substrate 4 after the element formation substrate 1 and the support substrate 2 are bonded to each other. The value can be brought close to the physical characteristic value of the supporting substrate 2.

Further, since the supporting substrate 2 in the semiconductor integrated circuit device is formed of a material (for example, alumina) having a thermal expansion coefficient substantially equal to that of the material forming the mounting substrate 5, the supporting substrate 2 And mounting board 5
It is possible to prolong the service life of the connection portion in the connection of the solder bump 3 with. Also, the reliability of the connecting portion can be improved.

Since the physical characteristic values such as the thermal expansion coefficient and the elastic coefficient of the semiconductor substrate 4 after the element forming substrate 1 and the supporting substrate 2 are bonded together can be made close to the physical characteristic values of the supporting substrate 2. It is possible to select a material having desired mechanical properties as the material of the support substrate 2.

As a result, a material having a large coefficient of thermal expansion can be used as the material of the support substrate 2, and as a result, it is not necessary to reinforce the semiconductor substrate 4 and the mounting substrate 5 with resin or the like, and The low-priced mounting board 5 can be used.

Further, since it is not necessary to reinforce the semiconductor substrate 4 and the mounting substrate 5 with resin or the like, the semiconductor substrate 4
Bare chip mounting can be enabled.

As a result, it is not necessary to fix the semiconductor substrate 4 with the resin or the like, so that when the defect occurs, the semiconductor substrate 4 is not formed.
Can be exchanged.

By using alumina for the support substrate 2, since alumina is a high melting point material, it is possible to withstand high heat in the diffusion process during the manufacture of semiconductor substrates.
Furthermore, by using alumina for the mounting board 5,
The life of the connection portion of the solder bump 3 can be extended, and the reliability of the connection portion can be improved.

(Embodiment 2) FIG. 2 is a sectional view showing an example of the structure of a semiconductor substrate and a semiconductor integrated circuit device using the same according to another embodiment of the present invention.

First, the semiconductor substrate of the second embodiment is a semiconductor substrate having an SOI structure similar to that of the semiconductor substrate described in the first embodiment, and its configuration will be described. It is a silicon wafer on which elements are formed. An element forming substrate 1,
The semiconductor substrate 4 of the second embodiment is composed of a supporting substrate 2 that supports the element forming substrate 1 by directly adhering it to the element forming substrate 1. Further, the semiconductor substrate 4 of the second embodiment also has a thickness of the supporting substrate 2 that is a component thereof. It is much thicker than the thickness of the formation substrate 1.

The other configurations of the semiconductor substrate 4 of the second embodiment and the functions of the respective constituent members are the same as those described in the first embodiment, and thus the duplicate description thereof will be omitted.

Here, the element forming substrate 1 and the supporting substrate 2
The method of pasting together with will be described.

First, since the supporting substrate 2 is made of alumina, which is a sintered material, its surface is very uneven when viewed microscopically. Therefore, the support substrate 2
The surface to be bonded to the element forming substrate 1 is polished, and the surface to be bonded is mirror-finished.

After that, the space between the element forming substrate 1 and the supporting substrate 2 is put into a vacuum state and pressure is applied, so that both can be bonded together.

This is because the alumina forming the support substrate 2 contains SiO ₂ as a binder (binder) at the time of sintering, so that this Si and the element forming substrate 1 which is a silicon wafer. It is tied and bonded to Si.

Next, the structure of the semiconductor integrated circuit device according to the second embodiment will be described. The semiconductor integrated circuit device uses a semiconductor substrate 4 having an SOI structure, which is composed of an element formation substrate 1 and a support substrate 2. The device is a semiconductor substrate 4, and solder bumps 3 are formed on the electrodes 1a on the element formation substrate 1.
And the mounting substrate 5 connected via the.

That is, the semiconductor substrate 4 is flip-chip mounted on the mounting substrate 5 via the solder bumps 3.

The other construction of the semiconductor integrated circuit device according to the second embodiment and the function of each constituent member are the same as those of the first embodiment.
Since it is the same as the one described above, the duplicated description will be omitted.

The operation and effect of the semiconductor substrate and the semiconductor integrated circuit device using the same according to the second embodiment will be described.

First, there is a semiconductor substrate 4 consisting of an element forming substrate 1 which is a silicon wafer on which elements are formed, and a supporting substrate 2 which directly adheres to the element forming substrate 1 to support the element forming substrate 1, Since the thickness of the supporting substrate 2 (about 400 to 800 μm) is much thicker than the thickness of the element forming substrate 1 (about 1 to 5 μm), the semiconductor after the element forming substrate 1 and the supporting substrate 2 are bonded together Physical characteristic values such as the thermal expansion coefficient and the elastic coefficient of the substrate 4 can be brought close to the physical characteristic values of the supporting substrate 2.

Further, since the supporting substrate 2 in the semiconductor integrated circuit device is formed of a material (for example, alumina) having a thermal expansion coefficient substantially equal to that of the material forming the mounting substrate 5, the supporting substrate 2 And mounting board 5
It is possible to prolong the service life of the connection portion in the connection of the solder bump 3 with. Also, the reliability of the connecting portion can be improved.

Since the other operations and effects of the semiconductor substrate of the second embodiment and the semiconductor integrated circuit device using the same are the same as those described in the first embodiment, duplicate description thereof will be omitted.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the semiconductor integrated circuit device described in the first and second embodiments, one semiconductor substrate is flip-chip mounted on the mounting substrate, but in the other embodiment of the present invention shown in FIG. As shown in a partial cross-sectional view of a semiconductor substrate and a semiconductor integrated circuit device using the semiconductor substrate, a plurality of semiconductor substrates 4 may be flip-chip mounted on a mounting substrate 5 via solder bumps 3, respectively. .

According to this, the semiconductor substrate 4 can be mounted at a high density in a processor unit such as a workstation or a personal computer.

[0063]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1). A semiconductor substrate comprising an element-forming substrate on which elements are formed and a supporting substrate that supports the element-forming substrate by being bonded to the element-forming substrate directly or via an oxide film, and the thickness of the supporting substrate is Since the element forming substrate is much thicker than the thickness of the element forming substrate, the physical characteristic values such as the thermal expansion coefficient and the elastic coefficient of the semiconductor substrate after the element forming substrate and the supporting substrate are bonded to each other are set to the physical values of the supporting substrate. It can be close to the characteristic value.

(2). Since the support substrate in the semiconductor integrated circuit device is formed of a material having a coefficient of thermal expansion substantially equal to that of the material forming the mounting substrate, connection in solder bump connection between the supporting substrate and the mounting substrate The life of the part can be extended.
In addition, the reliability of the connecting portion can be improved.

(3). Since the physical characteristic values such as the thermal expansion coefficient and elastic coefficient of the semiconductor substrate after adhering the element forming substrate and the supporting substrate can be made close to the physical characteristic values of the supporting substrate, the material of the supporting substrate is It will be possible to select a material with the desired mechanical properties.

(4). Since it becomes possible to select a material having desired mechanical properties as the material of the supporting substrate, it is possible to use a material having a large thermal expansion coefficient as the material of the supporting substrate, and as a result, the semiconductor substrate and the It is not necessary to reinforce with the mounting board with resin or the like, and a low-priced mounting board can be used.

(5). Since it is not necessary to reinforce with resin or the like between the semiconductor substrate and the mounting substrate, bare chip mounting of the semiconductor substrate can be enabled.

As a result, since it is not necessary to fix the semiconductor substrate with the resin or the like, it becomes possible to replace the semiconductor substrate when a defect occurs.

(6). By using alumina for the supporting substrate, alumina is a high melting point material, so it can withstand high heat in the diffusion process during semiconductor substrate manufacturing. Furthermore, by using alumina for the mounting substrate as well, solder bumps can be formed. It is possible to extend the service life of the connection part and further improve the reliability of the connection part.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the structure of a semiconductor substrate and a semiconductor integrated circuit device using the same according to the present invention.

FIG. 2 is a sectional view showing an example of the structure of a semiconductor substrate and a semiconductor integrated circuit device using the same according to another embodiment of the present invention.

FIG. 3 is a partial cross-sectional view showing an example of the structure of a semiconductor substrate and a semiconductor integrated circuit device using the same according to another embodiment of the present invention.

[Explanation of symbols]

 1 Element Forming Substrate 1a Electrode 2 Support Substrate 3 Solder Bump 4 Semiconductor Substrate 5 Mounting Substrate 5a Electrode 6 Oxide Film

Claims (4)

[Claims] 1. A semiconductor substrate having an SOI structure, comprising an element formation substrate on which elements are formed, and a support substrate that supports the element formation substrate by laminating it to the element formation substrate. A semiconductor substrate having a thickness much larger than that of the element forming substrate. 2. The semiconductor substrate according to claim 1, wherein the element formation substrate and the support substrate are bonded together via an oxide film. 3. The semiconductor substrate according to claim 1, wherein the supporting substrate is made of alumina. 4. A semiconductor integrated circuit device using the semiconductor substrate according to claim 1, 2 or 3, wherein solder bumps are provided on the semiconductor substrate and an electrode on an element forming substrate forming the semiconductor substrate. A semiconductor integrated circuit device comprising a connected mounting substrate, wherein the support substrate is formed of a material having a coefficient of thermal expansion substantially equal to a coefficient of thermal expansion of a material forming the mounting substrate.