JPH08213578A - Soi substrate and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To provide a technology enabling the prevention of the uneven rotation of an SOI substrate in processing with rotation of the substrate. CONSTITUTION: An SOI substrate 1 is composed of a completely circuit Si single crystal substrate 2 and an incompletely circular Si single crystal layer 4 having a main orientation flat 5 which is formed on that substrate 2 through an oxide film 3. Thus, the imcompletely circular layer 4 is supported on the completely circular substrate 2, this causing the center of gravity of the substrate 1 to coincide with the geographic symmetric center and hence in a processing with rotation of the substrate the uneven rotation of the SOI substrate 1 can be prevented during rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOI substrate and a method for manufacturing the same, and more particularly to the field of forming a desired element region in a semiconductor single crystal layer formed on a supporting substrate via an insulator. Regarding effective technology.

[0002]

2. Description of the Related Art For example, diffusion into a semiconductor single crystal layer such as a silicon single crystal formed on an insulator such as an oxide film,
As a technique for forming a desired element region by an impurity doping method such as ion implantation, SOI (Semico
The technique of "nducer on in-sulator" is known.

For example, "Latest Illustrated Semiconductor Guide", published by Seibundo Shinkosha Co., Ltd., October 2, 1989, P
98 to P99, a sapphire substrate is used as an insulator, a semiconductor single crystal layer made of a silicon single crystal is formed on the sapphire substrate by an epitaxial method, and a p-type semiconductor device is formed on the semiconductor single crystal layer. C-MOS consisting of MOS and n-MOS (C
equipment-ary Metal Oxide
SOS (Silicon On Sapphir) formed by a Semiconductor (Inductor) inverter.
e) Technology is described.

Since the SOI technique including such an SOS forms an element region in a semiconductor single crystal layer formed on an insulator, compared with the conventional technique of directly forming an element region on a semiconductor substrate, The advantage that the parasitic capacitance (stray capacitance) can be reduced is obtained.

SOI used in such SOI technology
An orientation flat for detecting the position of the semiconductor single crystal layer is formed on the substrate. This orientation flat shows the crystal orientation in the plane of the substrate, the main orientation flat used for positioning the substrate such as mask alignment in the process of device manufacturing, and the sub orientation for identifying the crystal orientation and conductivity type. There is an orientation flat. Usually, only the main orientation flat is formed.

When the SOI substrate has the main orientation flat or the sub-orientation flat as described above, the SOI substrate becomes asymmetric because the shape of the SOI substrate is not a non-round shape.

Further, an orientation notch is known as one having a function similar to that of the orientation flat.

For example, "Nikkei Microdevice", October 1989, P105-P110, published by Nikkei BP, describes a technique relating to such orientation flats and orientation notches.

[0009]

When a desired element region is formed in the semiconductor single crystal layer of the SOI substrate as described above, C
Although many process processing steps such as a VD film forming step are performed,
Since the SOI substrate has a non-round shape due to the formation of the orientation flat,
There is a problem that unevenness of rotation occurs in the SOI substrate in a process step involving the rotation of the substrate.

For example, in the CVD film forming process, the reaction is performed while rotating the SOI substrate while being supported by the susceptor in the reaction chamber. However, since the SOI substrate has a non-round shape, its center of gravity is geometric. Since it deviates from the center of symmetry, uneven rotation occurs during rotation. As a result, variations in the formed film thickness occur.

Such rotation unevenness becomes more remarkable as the size of the SOI substrate becomes larger (the diameter is about 150 mm or more). Therefore, considering that the demand for larger diameters will increase in the future, it is necessary to prevent uneven rotation in the process steps.

An object of the present invention is to provide a technique capable of preventing uneven rotation occurring in an SOI substrate during rotation in a process step involving the rotation of the substrate.

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.

[0014]

Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

(1) The SOI substrate of the present invention is an SOI substrate in which a semiconductor single crystal layer is formed on a supporting substrate with an insulator interposed therebetween, wherein the supporting substrate is a semiconductor substrate having a perfect circular shape, and The single crystal layer is a non-round circular single crystal semiconductor single crystal layer.

(2) The method for manufacturing an SOI substrate of the present invention is
A step of preparing a perfectly circular semiconductor substrate and a non-round semiconductor single crystal substrate in which a main orientation flat is formed in advance and an oxide film is formed on both surfaces, and the round semiconductor substrate and the non-round circle The method includes the steps of integrally bonding the shaped semiconductor single crystal substrates through an oxide film, and processing the non-round circular semiconductor single crystal substrate to a desired thickness.

(3) Another method of manufacturing an SOI substrate according to the present invention comprises the steps of preparing a perfect circular semiconductor single crystal substrate and forming an oxide film at a desired internal depth of the semiconductor single crystal substrate. Dividing the semiconductor single crystal substrate into a thin first single crystal layer and a thick second single crystal layer; masking a portion of the surface of the first single crystal layer other than a desired portion; Removing the unmasked desired portion of the single crystal layer to form a main orientation flat.

[0018]

According to the above-mentioned means (1), the SO of the present invention is
The I substrate is an SOI substrate in which a semiconductor single crystal layer is formed on a support substrate via an insulator, and the support substrate is a semiconductor substrate having a perfect circular shape, and the semiconductor single crystal layer is a non-perfect circular shape. Since the single crystal semiconductor is composed of a single crystal layer, it is possible to prevent uneven rotation occurring in the SOI substrate during rotation in a process step involving rotation of the substrate.

According to the above-described means (2), the method for manufacturing an SOI substrate of the present invention is a semiconductor substrate having a perfect circular shape, and a non-true semiconductor substrate in which a main orientation flat is previously formed and an oxide film is formed on both surfaces. A step of preparing a circular semiconductor single crystal substrate, a step of integrally bonding the perfectly circular semiconductor substrate and the non-round semiconductor single crystal substrate through an oxide film, and the non-round semiconductor Since the step of processing the single crystal substrate to a desired thickness is included, it is possible to prevent the rotation unevenness that occurs in the SOI substrate during the rotation in the process processing step involving the rotation of the substrate.

According to the above-mentioned means (3), another SOI substrate manufacturing method of the present invention comprises a step of preparing a semiconductor semiconductor crystal substrate having a perfect circular shape and a desired internal depth of the semiconductor single crystal substrate. And forming an oxide film to divide the semiconductor single crystal substrate into a thin first single crystal layer and a thick second single crystal layer, and masking a portion other than a desired portion of the surface of the first single crystal layer. And a step of removing a desired portion of the first single crystal layer which is not masked to form a main orientation flat. Therefore, in the process step involving the rotation of the substrate, the SOI during rotation is included. It is possible to prevent uneven rotation of the substrate.

Hereinafter, the present invention will be described in detail with reference to the drawings together with embodiments.

In all the drawings for explaining the embodiments, parts having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

[0023]

1A and 1B show an SOI substrate according to an embodiment of the present invention. FIG. 1A is a plan view and FIG. 1B is a sectional view taken along line AA of FIG. The SOI substrate 1 of the present embodiment is formed by a perfect circular silicon single crystal substrate 2 which is a supporting substrate, an oxide film 3 which is an insulator on the silicon single crystal substrate 2, and a main orientation on the side surface. It is composed of a non-round circular silicon single crystal layer 4 which is a semiconductor single crystal layer on which a flat 5 is formed.

Here, the silicon single crystal substrate 2 is, for example,
It has a diameter of 200 mm (8 inches), a thickness of 725 μm, and a plane orientation (100). The oxide film 3 has a thickness of, for example, 0.5 μm, and the silicon single crystal layer 4 has a thickness of, for example, 1 μm.
˜2 μm. Further, the main orientation flat 5 is formed, for example, at the position of the plane orientation (110). The position where this main orientation flat 5 is formed is the plane orientation (100) of the silicon single crystal layer 4.
A plane orientation suitable for is selected. The position where this main orientation flat 5 is formed is generally
The plane orientation indicated by (0, 1 bar, 1 bar) is selected.

Next, a method of manufacturing the SOI substrate 1 of this embodiment will be described in the order of steps with reference to FIGS.

First, as shown in FIG. 2, for example, a diameter of 20
0 mm (8 inches), thickness 725 μm, plane orientation (10
A perfect circular silicon single crystal substrate 2 having 0) is prepared. This silicon single crystal substrate 2 becomes a base substrate.
(A) is a plan view and (b) is a sectional view taken along line AA of (a). Similarly, as shown in FIG.
mm, thickness 725 μm, plane orientation (100), main orientation flat 5 is formed, and non-circular silicon single crystal substrate having oxide film 3 having a thickness of 0.5 μm formed on both sides, for example. (Bond substrate) 6 is prepared. This silicon single crystal substrate 6 will be a semiconductor region for forming an element region of a device which will be required later.

This non-round silicon single crystal substrate 6
As shown in FIG. 7, the main orientation flat 5 was processed in advance in the state of the silicon single crystal ingot 7, and then, as shown in FIG. 3A, it was processed into a wafer so as to have a plane orientation (100). Then, as shown in FIG. 3B, a thermal oxidation process is performed to form an oxide film 3 on both surfaces of the oxide film 3 for manufacturing.

Next, as shown in FIG. 4, the non-round circular silicon single crystal substrate 6 of FIG. 3 is placed on the round circular silicon single crystal substrate 2 of FIG. ℃ ~ 11
Heat treatment is performed at 00 ° C. for 2-3 hours in an atmosphere containing oxygen or nitrogen. As a result, both are chemically bonded through the oxide film 3 and are completely integrated.

Then, as shown in FIG. 5, the surface side of the silicon single crystal substrate 6 is polished by, for example, a surface grinder to polish it to a thickness of several 10 μm. The broken line shows the position before polishing. By reducing the thickness,
The silicon single crystal substrate 6 is changed to a silicon single crystal layer 8.

Next, as shown in FIG. 6, the surface side of the silicon single crystal layer 8 is further mirror-polished by a mechanical / chemical polishing method so that the silicon single crystal layer 8 has a desired thickness, for example. Mirror polishing treatment is performed until it becomes 1 to 2 μm.

As described above, the SOI as shown in FIG.
The substrate 1 is completed. The SOI substrate 1 thus manufactured is subjected to process treatment such as diffusion and ion implantation on the silicon single crystal layer 8 to form a desired element region as described later. Be seen.

In the process of FIG. 4, when the silicon single crystal substrate 6 on which the main orientation flat 5 is formed in advance is bonded to the silicon single crystal substrate 2, the main orientation flat 5 is subjected to a specific crystal of the silicon single crystal substrate 2. When it is necessary to match the orientations, as shown in FIG. 8, an orientation notch 9 is formed in advance in the silicon single crystal substrate 2, and the silicon single crystal substrate 6 is bonded based on this orientation notch 9. It should be done. Further, a sub-orientation flat is formed on the silicon single crystal substrate 6 if necessary. The method of forming this sub-orientation flat is
It can be performed in the same manner as the method of forming the main orientation flat 5 as described above.

Next, an example of another method of manufacturing the SOI substrate 1 of this embodiment will be described with reference to FIGS. 9 to 14. In this manufacturing method, one silicon single crystal substrate is used as a starting material in advance, and various process treatments are gradually applied to this silicon single crystal substrate to finally obtain a non-perfect circular shape. It is characterized in that the silicon single crystal layer is formed on a perfectly circular silicon single crystal substrate.

First, as shown in FIG. 9, for example, a diameter of 20
0 mm (8 inches), thickness 725 μm, plane orientation (10
0), and by forming an oxide film 11 to a desired internal depth in advance, a perfect circular silicon which is divided into a thin first silicon single crystal layer 13 and a thick second silicon single crystal layer 14. A single crystal substrate 12 is prepared. The first silicon single crystal layer 13 becomes a semiconductor region for forming an element region, and the second silicon single crystal layer 14 becomes a base substrate. The oxide film 11 has a thickness of 0.4 μm, for example.
The silicon single crystal layer 13 has a thickness of 0.2 μm, for example, and the second silicon single crystal layer 14 has a thickness of approximately 725 μm. (A) is a plan view, (b) is A of (a)
It is -A sectional drawing.

This silicon single crystal substrate 12 is shown in FIG.
As shown in (a), oxygen ions are introduced from the surface of the silicon single crystal substrate 12 obtained by wafer processing,
For example, acceleration energy: 180 KeV, dose: 2.
After being implanted under the condition of 0 × 10 ¹⁸ / cm ^2, the treatment is performed in a nitrogen atmosphere at about 1280 ° C. for 6 hours.
As shown in (b), the oxide film 11 is formed on the silicon single crystal substrate 12
It is manufactured by forming it to the inner depth of. So-called SIMOX
(Separation-by-implanted-
The silicon single crystal substrate 12 is formed by the oxygen) technique.

Next, as shown in FIG. 10, the adhesive tape 15 is covered on the portion to be removed with the line forming the main orientation flat on the surface of the silicon single crystal layer 13 of the silicon single crystal substrate 12 as a boundary.

Subsequently, as shown in FIG. 11, a photoresist 16 is applied to the surface of the silicon single crystal layer 12 including the adhesive tape 15.

Next, as shown in FIG. 12, the adhesive tape 1
By peeling 5 away, the photoresist 16 on this is removed at the same time. As a result, the photoresist 16 is masked except for the portion where the main orientation flat is to be formed.

Then, as shown in FIG. 13, the silicon single crystal substrate 12 is immersed in a hydrofluoric acid / nitric acid type etching solution to partially remove the unmasked silicon single crystal layer 13 using the photoresist 16 as a mask. To remove
Form the main orientation flat 5. This step can be performed not only by wet etching but also by dry etching.

Next, as shown in FIG. 14, after removing the photoresist 16 with an organic solvent, the silicon single crystal substrate 12 is washed.

As described above, the SOI as shown in FIG.
The substrate 1 is completed. For the SOI substrate 1 manufactured in this way, the SO substrate obtained by the above-mentioned manufacturing method is used.
Similar to the case of the I substrate 1, the silicon single crystal layer 13 is subjected to process treatment such as diffusion and ion implantation to form a desired element region.

When it is necessary to match the main orientation flat 5 of the silicon single crystal layer 13 with a specific crystal orientation, the thick second silicon single crystal layer 14 in the silicon single crystal substrate 12 of FIG. 9 is previously formed. The orientation notch should be formed. Further, a sub-orientation flat may be formed on the silicon single crystal substrate 12 if necessary.

FIG. 15 shows the SOI obtained by this embodiment.
1 shows an example in which a C-MOS inverter having a silicon gate is formed as a device on a silicon single crystal layer 4 using a substrate 1. 18 is a p-MOS transistor, 19 is a P + type source region, 20 is a P + type drain region, 21 is a gate oxide film, 22 is an N type channel region, 2
3 is a source electrode, 24 is a drain electrode, 25 is a silicon gate metal, and 26 is a protective oxide film. A gate electrode is connected to the silicon gate metal 25 at a position not shown. On the other hand, 28 is an n-MOS transistor, 29 is an N + type source region, 30 is an N + type drain region, 31 is a gate oxide film, 32 is a P type channel region, 3
Reference numeral 3 is a source electrode, and 34 is a silicon gate metal. The drain electrode 24 and the protective oxide film 26 are common.

According to this embodiment, the following effects can be obtained.

(1) In the SOI substrate 1, a non-round circular silicon single crystal layer 4 in which a main orientation flat 5 is formed is formed on a true circular silicon single crystal substrate 2 via an oxide film 3. Since it is configured as described above, it is possible to prevent uneven rotation occurring in the SOI substrate at the time of rotation in a process step involving rotation.

That is, the non-round circular silicon single crystal layer 4 is supported by the round circular silicon single crystal substrate 2 so that the center of gravity of the SOI substrate 1 coincides with the geometric center of symmetry. Therefore, even in a process step involving the rotation of the substrate such as a CVD film forming step, the uneven rotation does not occur during the rotation, so that the film thickness does not vary. As a result, it becomes possible to sufficiently cope with the demand for a larger diameter in particular.

(2) Since the SOI substrate 1 can be easily manufactured by combining well-known process treatment techniques, the SOI substrate 1 can be mass-produced without increasing the cost.

As described above, the invention made by the present inventor is
Although the present invention has been specifically described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention.

For example, in the above-mentioned embodiment, the material of the supporting substrate, the semiconductor single crystal layer and the insulator has been described by taking a specific material as an example, but the material is not limited to this and equivalent materials can be used.

In the above embodiments, the values of the thickness, crystal orientation, etc. in the silicon single crystal substrate, the silicon single crystal layer, etc., or the conditions in various process treatment steps are merely examples. It can be changed as desired.

Further, the main orientation flat formed in the silicon single crystal layer forming the element region can achieve the purpose by itself, but a sub orientation flat may be formed if necessary.

In the above description, the invention made by the present inventor is the field of application which is the background of the invention.
Although the case where the technology is applied to the technology has been described, the invention is not limited thereto. The present invention is applicable at least under the condition that a desired element region is formed in a semiconductor single crystal layer formed on an insulator.

[0053]

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

Since the non-round semiconductor single crystal layer having the main orientation flat is formed on the perfect circular semiconductor substrate via the insulator to form the SOI substrate, a process involving rotation is performed. In the processing process,
It is possible to prevent uneven rotation occurring in the SOI substrate during rotation.

[Brief description of drawings]

1A and 1B show an SOI substrate according to an embodiment of the present invention, FIG. 1A is a plan view, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 shows one step of a method for manufacturing an SOI substrate according to an embodiment of the present invention, (a) is a plan view, (b) is (a).
FIG.

3A and 3B show another step of the method for manufacturing an SOI substrate according to the embodiment of the present invention, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line AA of FIG.

FIG. 4 is a cross-sectional view showing another step of the method for manufacturing the SOI substrate according to the example of the present invention.

FIG. 5 is a cross-sectional view showing another step of the method for manufacturing the SOI substrate according to the example of the present invention.

FIG. 6 is a cross-sectional view showing another step of the method for manufacturing an SOI substrate according to the example of the present invention.

FIG. 7 is a perspective view showing another step of the method for manufacturing the SOI substrate according to the embodiment of the present invention.

FIG. 8 is a plan view showing another step of the method for manufacturing the SOI substrate according to the embodiment of the present invention.

9A and 9B show a step of another method of manufacturing an SOI substrate according to an embodiment of the present invention, wherein FIG. 9A is a plan view and FIG. 9B is a sectional view taken along line AA of FIG. 9A.

FIG. 10 is a cross-sectional view showing another step of another method of manufacturing an SOI substrate according to the embodiment of the present invention.

FIG. 11 is a cross-sectional view showing another step of another method of manufacturing an SOI substrate according to the embodiment of the present invention.

FIG. 12 is a cross-sectional view showing another step of another method of manufacturing an SOI substrate according to the embodiment of the present invention.

FIG. 13 is a cross-sectional view showing another step of another method of manufacturing an SOI substrate according to the embodiment of the present invention.

FIG. 14 is a cross-sectional view showing another step of another method of manufacturing an SOI substrate according to the example of the present invention.

FIG. 15 illustrates a C-MO on an SOI substrate according to an embodiment of the present invention.
It is sectional drawing which shows the example which formed the S inverter.

[Explanation of symbols]

1 ... SOI substrate, 2, 12 ... True circular silicon single crystal substrate, 3, 11 ... Oxide film, 4 ... Silicon single crystal layer, 5 ...
Main orientation flat, 6 ... Non-circular silicon single crystal substrate, 7 ... Silicon single crystal ingot, 8 ...
Non-round circular silicon single crystal layer, 9 ... Orientation notch, 13 ... Thin silicon single crystal layer, 14 ... Thick silicon single crystal layer, 15 ... Adhesive tape, 16 ... Photoresist, 18 ... N-MOS transistor, 19 ... P + type source region, 20 ... P + type drain region, 21, 31 ... Gate oxide film, 22 ... N type channel region, 23, 33 ... Source electrode, 24 ... Drain electrode, 25, 34 ... Silicon gate metal, 26 ... Protection Oxide film, 28 ... N-MOS transistor, 29 ... N + type source region, 30 ... N + type drain region, 32 ... P type channel region.

Claims (7)

[Claims] 1. In an SOI substrate in which a semiconductor single crystal layer is formed on a supporting substrate via an insulator, the supporting substrate is a semiconductor substrate having a perfect circular shape, and the semiconductor single crystal layer has a non-perfect circular shape. 2. An SOI substrate comprising the semiconductor single crystal layer of. 2. The SOI substrate according to claim 1, wherein a main orientation flat is formed on the semiconductor single crystal layer. 3. The SOI substrate according to claim 1, wherein the semiconductor single crystal layer has a main orientation flat and a sub-orientation flat. 4. The SOI substrate according to claim 1, wherein an orientation notch is formed in the semiconductor substrate. 5. The semiconductor substrate and the semiconductor single crystal layer are both made of silicon.
The SOI substrate according to any one of 1. 6. A step of preparing a perfect circular semiconductor substrate and a non-perfect circular semiconductor single crystal substrate in which a main orientation flat is formed in advance and an oxide film is formed on both surfaces thereof, and the perfect circular semiconductor. A step of integrally bonding the substrate and the non-circular semiconductor single crystal substrate through an oxide film,
And a step of processing the non-circular semiconductor single crystal substrate into a desired thickness. 7. A step of preparing a semiconductor single crystal substrate having a perfect circular shape, and an oxide film is formed at a desired internal depth of the semiconductor single crystal substrate to form the semiconductor single crystal substrate as a thin first single crystal layer. Dividing into a thick second single crystal layer, masking a portion other than a desired portion of the surface of the first single crystal layer, and removing an unmasked desired portion of the first single crystal layer. And a step of forming a main orientation flat.