JPH0573331B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a GaAs/Si laminate in which gallium arsenide (GaAs) is laminated on a silicon (Si) substrate,
The present invention relates to a method for growing GaAs on a silicon substrate.

(Prior art) With the diversification and demand for faster speed of electronic equipment,
Compound semiconductor devices are attracting attention as electronic devices that can meet this demand.

As such compound semiconductor devices, those using so-called − group compound semiconductors are well known, and in particular those using compounds of gallium (Ga) and arsenic (As) are silicon (hereinafter simply referred to as Si). Compared to conventional semiconductor devices mainly composed of It is attracting attention because of its

However, the currently available GaAs single crystal is small in size compared to a Si substrate, that is, its diameter is small, which has been a major hindrance in producing large devices. Furthermore, since GaAs substrates are more expensive than silicon, consideration must be given to reducing device costs.

For this reason, various attempts have been made in the past to grow an epitaxial layer of GaAs on a substrate other than a GaAs substrate, such as a silicon substrate, to obtain a large and inexpensive substrate equivalent to a GaAs substrate.

An example of such an attempt is the
There are methods for growing compound semiconductors proposed in No. 62-028114 and Japanese Patent Application No. 62-069165.

The growth methods according to these proposals will be briefly explained below with reference to FIGS. 3A and 3B. Furthermore, the third
Figures A and B are manufacturing process diagrams schematically showing the growth methods according to both proposals.

According to these methods, an insulating film such as a SiN film shown at 13 is laminated on the back surface of a silicon substrate shown at 11 at a relatively low temperature (FIG. 3A). Next, this silicon substrate 11 with an insulating film is annealed at a high temperature, and the silicon substrate 11 is intentionally warped by utilizing the difference in thermal expansion coefficient between the silicon substrate and the insulating film (FIG. 3B). Next, GaAs is grown on the surface of the silicon substrate 11 with the insulating film 13 stacked or removed. At this time, silicon substrate 1
1 is due to the difference between the coefficient of thermal expansion of GaAs and the coefficient of thermal expansion of silicon, which causes a force that causes warping in the opposite direction to the conventional warping, and as a result, warping of the substrate becomes a practical problem. We were able to reduce it to a minimum.

(Problem to be Solved by the Invention) However, although the above-mentioned conventional methods are certainly effective in reducing warpage of silicon substrates,
There was a problem that the stress within the GaAs layer could not be alleviated.

In fact, by the method described above, a diameter of 2
When a GaAs layer is grown on an inch (1 inch is about 2.54 cm, hereinafter the same) silicon substrate, cracks will occur in the GaAs layer when the grown film thickness becomes about 5 μm. Therefore, in the conventional method,
It was not possible to further increase the thickness of the GaAs growth layer.

The present invention was made in view of the above points, and therefore, an object of the present invention is to provide a laminate in which a GaAs layer is laminated on a silicon base (for example, a silicon substrate), in which the stress in the GaAs layer is extremely high. small
It is an object of the present invention to provide a GaAs/Si laminate and a GaAs growth method that can easily obtain such a laminate.

(Means for solving the problem) In order to achieve this purpose, this invention
According to the GaAs/Si laminate, an insulating film is partially provided on the surface of a silicon (Si) base, and the layers grow from the exposed area of the silicon base and are connected with each other while leaving a void on the insulating film. It is characterized by comprising a GaAs layer that has become a single growth layer.

Further, according to the GaAs growth method of the present invention in which a GaAs layer is grown on a silicon (Si) substrate, there are a step of depositing an insulating film on the silicon substrate, and a step of removing a predetermined region of this insulating film and performing the above-described steps. A process of partially exposing the silicon base and depositing GaAs on the exposed area of the silicon base described above.
The cross-sectional area of this GaAs growth layer taken parallel to the exposed surface of the silicon base described above is grown so that it expands as the growth layer grows, and the layers are connected with each other while leaving a void on the insulating film. The method is characterized in that it includes a step of forming two growth layers.

Here, the silicon base refers to, for example, a silicon substrate or an epitaxially grown layer of silicon, and may also be the entire surface or a part of the surface of the epitaxial layer on the surface of the silicon substrate.

Furthermore, in carrying out the above-described GaAs growth method, it is preferable to determine a predetermined region in which the insulating film is to remain, taking into account the crystal orientation of the silicon substrate. Furthermore, it is preferable to grow a GaAs layer on a silicon substrate on which an insulating film remains in a predetermined region using MOCVD (metal organic chemical vapor deposition).

(Function) According to the GaAs/Si laminate of the present invention, GaAs
The layer contacts the silicon (Si) base only in areas exposed from the insulating film on the silicon base. Therefore, since the area of the GaAs layer in contact with the silicon base is reduced, the stress in the GaAs layer caused by the difference between the thermal expansion coefficient of Si and the thermal expansion coefficient of GaAs is reduced. Furthermore, due to the existence of emptiness
Since the GaAs layer does not contact the insulating film, this also reduces stress in the GaAs layer.

Furthermore, according to the GaAs growth method of this invention,
The GaAs layer does not substantially grow on the insulating film. Then, it grows on the exposed areas of the silicon substrate.
The GaAs growth layer grows so that the cross-sectional area parallel to the exposed surface of the silicon base expands, so as the growth progresses, it grows on the adjacent exposed area.
One GaAs growth layer is formed by connecting GaAs comrades and leaving empty spaces on the insulating film.

Also, the insulating film is removed taking into consideration the crystal direction of the silicon base, that is, the insulating film is left taking into account the crystal direction, and the insulating film is removed on the silicon base including this insulating film.
When GaAs is grown using the MOCVD method, this
The GaAs growth layer grows easily so that the cross-sectional area of the GaAs growth layer, taken parallel to the exposed surface of the silicon base described above, expands.

(Example) Hereinafter, with reference to the drawings, GaAs/Si of the present invention will be described.
An example of a stacked body and an example of a method for growing GaAs will be explained respectively. However, the drawings used in the explanation are merely shown schematically to the extent that the invention can be understood, and therefore, the dimensions, shapes, and arrangement relationships of the constituent components in the drawings are limited to only the illustrated examples. However, it is clear that various modifications or changes may be made. Further, in each figure, similar components are designated by the same reference numerals.

Explanation of GaAs/Si laminate First, for an example of a GaAs/Si laminate, a silicon base is used as a silicon substrate, and the entire surface of this substrate is
An example will be explained using a GaAs/Si laminated substrate including a GaAs layer. FIG. 1A is a plan view showing an example of the GaAs/Si multilayer substrate, and FIG. 1B is an enlarged view of a part of the multilayer substrate indicated by P in FIG. 1A.
FIG.

In both figures, 21 indicates a silicon (Si) substrate. This silicon substrate 21 has an insulating film partially shown at 23 on its surface. In this embodiment, the term "partially provided with an insulating film" refers to a state in which a large number of striped insulating films 23 are provided in parallel at regular intervals on the surface of the silicon substrate 21.
Furthermore, in this case, the stripe direction of the insulating film 23 is parallel to the orientation flat indicated by 21a formed on the silicon substrate 21. The silicon substrate 21 is exposed at a portion where the insulating film 23 is not present, and the exposed area is shown as 21 in FIG. 1B.
It is shown with b.

Moreover, this silicon substrate 21 including an insulating film 23
A GaAs layer 25 is grown from a region 21b exposed from the insulating film 23 of the silicon substrate 21 and has a void on the insulating film 23.
This gap is shown at 25a in FIG. 1B.

According to the structure of the GaAs/Si laminated substrate configured as described above, the GaAs layer 25 contacts the silicon substrate 21 only at the exposed region 21b, and does not substantially contact the insulating film 23.

Note that the insulating film 23 provided on the silicon substrate 21
The shape, arrangement direction, and arrangement position are not limited to the above example, and can be changed depending on the design of the GaAs/Si multilayer substrate.

In addition, in the above example, GaAs is deposited on the entire surface of the silicon substrate.
The explanation is given using a GaAs/Si substrate with a layer of GaAs/Si as an example.
It is clear that the present invention is also applicable to structures that include. Furthermore, it is of course applicable even if the silicon base is an epitaxially grown layer of silicon.

Explanation of method for growing GaAs Next, an embodiment of the method of the present invention for growing GaAs on a silicon substrate will be described using an example in which a silicon substrate is used as a silicon substrate and a GaAs layer is grown on the entire surface of this substrate. . However, it should be understood that the numerical conditions, names of chemicals used, names of devices, etc. described in the following examples are merely examples, and these may be changed depending on the design.

FIGS. 2A to 2D are manufacturing process diagrams of the example,
Figure 2A
is a plan view, Figure 2B is an enlarged plan view of the part indicated by R in Figure 2A, and Figure 2C is a plan view.
and D are shown as cross-sectional views (details will be described later), respectively.

First, in this embodiment, a silicon substrate with a diameter of 2 inches is prepared. For example, a SiN film as an insulating film is deposited on this silicon substrate shown at 21 at a temperature of about 300°C by plasma CVD.
Form to a film thickness of 500 Å.

Next, a predetermined region of this SiN film is removed by photolithography to partially expose the silicon substrate 21. In this case, the removal of the SiN film is
The width of the SiN film (indicated by W ₁ in FIG. 2B) is about 2 μm, and it is formed into stripes, and the stripe direction is along the orientation flat 21a of the silicon substrate 21.
The striped SiN films should be parallel to the direction of
W (indicated by ₂ ) are opened so that they remain parallel. The silicon substrate 21 is exposed from the insulating film 23 in this space portion 21b.

Next, on the exposed region 21b of the silicon substrate 21,
Selective growth is performed to grow GaAs so that the cross-sectional area of the GaAs growth layer taken parallel to the exposed surface 21b of the silicon substrate expands as the growth layer grows. In this example, this selective growth is
The MCVD method, which is a MOCVD method (metal-organic chemical vapor deposition method) and uses a two-step growth method, is used as described below.

Hydrogen (H ₂ ) gas is used as the carrier gas,
Arsine (AsH ₃ ) and trimethyl gallium (hereinafter sometimes abbreviated as TMG) are used as reaction gases, respectively.

The above-mentioned silicon substrate 2 partially provided with a SiN film
1 at a predetermined position in the reactor of the MOCVD apparatus. Next, the temperature inside the reactor is raised to 900 to 980° C. in an atmosphere of both H ₂ and AsH ₃ gases, and the substrate surface is cleaned at this temperature for 5 minutes. Next, after lowering the temperature inside the reactor to approximately 400°C, TMG was introduced into the reactor and deposited on this substrate.
A GaAs buffer layer is grown to a thickness of about 100 Å.
After that, the introduction of TMG was stopped, the growth of GaAs was temporarily interrupted, and the temperature inside the reactor was raised to approximately 650℃, and then TMG was reintroduced into the reactor to form the second layer.
Perform GaAs growth.

Figure 2 C and D for an overview of the growth process of GaAs
Explain with reference to. Note that these figures are for GaAs/
2 is a cross-sectional view of the Si laminated substrate cut in a direction perpendicular to the stripe direction of the SiN film 23. FIG.

In the growth using the MOCVD method mentioned above,
The GaAs layer selectively grows on the region 21b exposed from the insulating film of the silicon substrate 21, and
As the layer grows, the cross-sectional area parallel to the surface of the silicon exposed region of the growth layer expands, so that the growth maintains an inverted mesa shape in FIG. 2C. Accordingly
As GaAs is grown to a larger thickness, it grows on adjacent exposed areas of the silicon substrate.
As shown in FIG. 2D, the GaAs layers are connected to form a single growth layer with voids 25a formed on the SiN film 23. As the growth of GaAs continues, the thickness of the grown layer increases while the voids are maintained since no reactant gas is supplied to the voids 25a.

As a result, the surface of the silicon (Si) substrate 21 is partially provided with the SiN film 23, and the silicon substrate 21 including the SiN film 23 is partially provided with the silicon substrate 23.
It grows from the region 21b exposed from the SiN film 23 of No. 1 and has a void 25b on the SiN film 23.
A GaAs/Si laminate including a GaAs layer 25 could be obtained.

Even when GaAs was grown to a thickness of about 5 μm using the above-described growth method, no cracks were observed in the GaAs layer.

Note that the method for growing a GaAs layer according to the present invention is not limited to the above-mentioned example, and various modifications can be made, for example, as described below.

For example, a vanadium-doped GaAs layer is grown on a silicon substrate to form a semi-insulating GaAs layer, and a non-doped GaAs layer is grown on top of this to form an SOI to form a three-dimensional circuit element. (Semiconductor on Insulator) structure can also be configured.

Also, GaAs is deposited on a part of the silicon substrate.
If the silicon base is an epitaxial growth layer of silicon and the layer is grown on this layer,
It is clear that the growth method of the present invention can also be used when growing a GaAs layer.

In addition, the insulating film is not limited to SiN film,
It can be any suitable insulator suitable for selective growth such as SiO ₂ .

Furthermore, the means for growing GaAs is not limited to the MOCVD method, and other growth methods such as the Hydrode-VPE method may also be used.

Further, the SiN film and the deposition method are not limited to the plasma CVD method, but may be a chemical vapor deposition method other than plasma, a low-temperature sputtering method, or other deposition method.

(Effects of the invention) As is clear from the above explanation, the effects of this invention are
According to the GaAs/Si stack, the contact area of the GaAs layer with the silicon base is reduced, which results from the difference between the coefficient of thermal expansion of Si and that of GaAs.
Stress in the GaAs layer is reduced. Furthermore, since the GaAs layer does not come into contact with the insulating film due to the presence of the void, the stress in the GaAs layer is also reduced by this.

For this reason, it is a laminate in which GaAs layers are stacked on a silicon base (for example, a silicon substrate).
A GaAs/Si laminate with extremely low stress in the GaAs layer can be obtained.

Furthermore, according to the GaAs growth method of this invention,
The GaAs layer does not substantially grow on the insulating film. Furthermore, it grows on exposed areas of the silicon substrate.
The GaAs growth layer grows so that the cross-sectional area parallel to the exposed surface of the silicon base expands, so as the growth progresses, GaAs comrades growing on adjacent exposed areas leave voids on the insulating film. They connect together and form a single growth layer. As a result,
The stress in the GaAs layer is reduced, and in fact the GaAs layer is 5 μm thick.
No cracks were observed even after the plants were grown to a certain extent.

For this reason, the stress in the GaAs layer is low.
A method for growing GaAs that can form a Si stack can be provided.

[Brief explanation of the drawing]

1A and B are diagrams for explaining the GaAs/Si laminate of the present invention, FIGS. 2A to D are manufacturing process diagrams for explaining the GaAs growth method of the present invention, and FIGS. 3A and B 1 is a manufacturing process diagram for explaining a conventional GaAs growth method. 21...Silicon base (silicon substrate), 21
a... Orientation flat, 21b...
Region exposed from the silicon-based insulating film, 23...
...Insulating film, 25...GaAs layer, 25a...Void.

Claims (1)

[Claims] 1. Partially provided with an insulating film on the surface of a silicon (Si) base, and grown from an exposed region of the silicon base,
A GaAs/Si laminate comprising GaAs layers that are connected to form a single growth layer with a void left on the insulating film. 2. When growing a GaAs compound semiconductor on a silicon (Si) base, there are two steps: depositing an insulating film on the silicon base, and removing a predetermined region of the insulating film to partially expose the silicon base. and GaAs on the exposed area of the silicon base.
The GaAs grown layer is grown so that its cross-sectional area parallel to the exposed surface of the silicon base expands as the grown layer grows, leaving a void above the insulating film and forming a single layer connected to each other. A method for growing GaAs, comprising the step of forming a growth layer. 3. The method according to claim 2, wherein the predetermined region is determined in consideration of a crystal direction of a silicon base.
How to grow GaAs.