JPH08153863A - Manufacture of soi laminated semiconductor substrate - Google Patents

Abstract

PURPOSE: To obtain uniform film thickness of a SOI film by a method wherein the main surface of a second semiconductor silicon wafer is closely adhered to the main surface of a first semiconductor silicon wafer to perform heat treatment, the second semiconductor silicon wafer is ground and is polished until oxide films are exposed and after the exposed oxide films are removed, the surface of the first semiconductor silicon wafer is flattened. CONSTITUTION: Oxide films 3 and 4 are respectively formed on the main surfaces of both of first and second semiconductor silicon wafers 1 and 2. Then, the main surface of the wafer 2 is made to closely adhere to the main surface of the wafer 1, a heat treatment is performed to form respectively polycrystalline silicon films 7 on the main surfaces of both of the wafers 1 and 2 and insular oxide films 7a are single-crystallized 9. The wafer 2 is ground and is polished until damage does not reach these single-crystallized 9 insular oxide films 7a and moreover, after the exposed films 7a are removed, the surface of the wafer 1 is flattened to obtain a SOI film 10. Thereby, an irregularity in the film thickness of the film 10 is small and the more uniformly formed film thickness of the SOI film can be realized.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thin film SOI manufactured by directly adhering two semiconductor silicon wafers.
The present invention relates to a method for manufacturing a laminated semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, a thin film SOI (silicon on insulator) formed by a polish stop method after a first silicon wafer and a second silicon wafer are bonded together with a dielectric layer interposed therebetween.
or) laminated semiconductor substrates are known.

The conventional SOI laminated semiconductor substrate 4 is formed in the order shown in FIGS. 3 (a) to 3 (f), for example. 3A to 3F are cross-sectional views showing the order of manufacturing steps.

First, as shown in FIG. 3A, the surface of the mirror-polished first silicon wafer 11 is oxidized to form an oxide film 12 having a thickness of about 0.5 μm. A cleaning process is performed on the bonding surfaces of both 11 and the second silicon wafer 13.

Next, as shown in FIG. 3 (b), the first silicon wafer 11 and the second silicon wafer 13 are brought into close contact with each other at room temperature and heat-treated at a temperature of 800 ° C. or higher to both silicon wafer 11 and silicon. The oxide film (dielectric layer) 12 is interposed between the wafers 13 and bonded.

Further, as shown in FIG. 3C, a diamond blade having a blade thickness of about 1 mm is applied to the first silicon wafer 11 along the dicing line, for example, 1
The 7.5 mm square grooves 14 are formed in a lattice shape with a depth such that the first silicon wafer 11 is left by about 10 μm.

Next, as shown in FIG. 3D, the bottom surface 14 of the groove 14 is reached until the oxide film 12 existing between the first silicon wafer 11 and the second silicon wafer 13 is reached.
a is etched with, for example, KOH.

Then, as shown in FIG. 3E, a thin film of a material having a polishing rate slower than that of a silicon wafer under the same conditions, for example, an oxide film 15 of 0.2 μm is formed on the groove bottom surface 14a.
Form about m.

Finally, as shown in FIG. 3 (f), the surface of the first silicon wafer 11 is aligned with the upper surface of the oxide film layer 15 formed on the groove bottom surface 14a by grinding and polishing, and the active region layer 16 is formed. By forming it, the SOI laminated semiconductor substrate 17 having a uniform silicon layer thickness is manufactured.

[0010]

However, in the SOI laminated semiconductor substrate manufactured by the conventional manufacturing method, it is possible to adjust the thickness (film thickness) of the active region layer by the thickness of the oxide film. However, when a more uniform SOI film thickness is required, there is a problem of overpolishing, and it is difficult to satisfy the above requirement. That is, in FIG. 3F, there is a problem that the active region layer 16 is overpolished by grinding and polishing.

In addition to the polish stop method, SO
The etch stop method is known as a technique for making the I film thickness uniform, but this method has a problem in that the processing cost increases because various processing steps are required.

Further, although a local plasma etching method or the like has been proposed, this method also has a problem that the processing cost increases.

Therefore, according to the present invention, there is little variation in the SOI film thickness, it is possible to obtain a more uniform SOI film thickness, there is no fear of overpolishing, and the processing cost can be reduced. The purpose is to obtain a method for manufacturing a substrate.

[0014]

The present invention comprises at least two aspects.
In a method for manufacturing an SOI laminated semiconductor substrate, which is manufactured by directly adhering one semiconductor silicon wafer, oxide films are formed on both main surfaces of a first semiconductor silicon wafer and a second semiconductor silicon wafer whose main surfaces are mirror-polished. Then, polycrystalline silicon or amorphous silicon is formed on the main surface of the first semiconductor silicon wafer or the second semiconductor silicon wafer, and the main surface of the first semiconductor silicon wafer and the main surface of the second semiconductor silicon wafer are adhered to each other. Of the second semiconductor silicon wafer, and then grinding and polishing the second semiconductor silicon wafer until the oxide film is exposed, further removing the exposed oxide film, and then planarizing the surface of the SOI laminated semiconductor substrate. It is a manufacturing method.

Further, according to the present invention, the oxide film of the first semiconductor silicon wafer is 200 Å or more, the oxide film thickness of the second semiconductor silicon wafer and the polycrystalline silicon or amorphous silicon surface is 100 Å or less, The surface roughness (center line average roughness, 250 μm square) of crystalline silicon or amorphous silicon is set to 10 Å or less, or the polycrystalline silicon or amorphous silicon is doped with impurities (P, Sb, As, B).

Further, according to the present invention, the heat treatment after the adhesion is 800
The amine-based solution is used for polishing at a temperature of not less than 0 ° C. or for polishing to expose the oxide film.

[0017]

Therefore, according to the present invention, the thin oxide film interposed between the second semiconductor silicon wafer and the polycrystalline silicon or amorphous silicon layer is locally blurred due to the heat treatment, and the polycrystalline silicon or amorphous The silicon layer is monocrystallized, and an island-shaped oxide film layer is present on the monocrystallized silicon layer. Therefore, when grinding and polishing the second semiconductor silicon wafer, by using an amine-based solution that does not react with the oxide film as the polishing liquid, polishing can be stopped at the island-shaped oxide film layer, and the island-shaped oxide film thickness is removed. Then, the SOI laminated semiconductor substrate can be easily obtained.

As described above, according to the present invention, the SOI film thickness can be determined by the thickness of polycrystalline silicon or amorphous silicon, and the S0I laminated semiconductor substrate of about 0.1 μm can be manufactured at low cost.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an SOI laminated semiconductor substrate according to the present invention will be described below with reference to the drawings.

1A to 1F show S in this embodiment.
It is sectional drawing which shows the manufacturing process sequence of an OI laminated semiconductor substrate. In the figure, 1 is a first silicon wafer, 2 is a second silicon wafer.
It is a silicon wafer.

To manufacture an SOI laminated semiconductor substrate, first, as shown in FIG. 1 (a), a second silicon wafer 2 is used.
Then, cleaning such as SC1 and SC2 cleaning or thermal oxidation is performed to form an oxide film 4 such as a natural oxide film or a thermal oxide film having a thickness of about 100 Å or less. The reason why the oxide film 4 is set to about 100 Å or less is
This is because, as will be described later, when the oxide film becomes too thick, the oxide film remains as a layer, and polycrystalline silicon or amorphous silicon is not single-crystallized.

Further, an oxide film 3 having a thickness of 200 Å or more is formed on the first silicon wafer 1 by thermal oxidation or CVD, for example, 100.
Form 0Å. The reason why it is set to 200 Å or more is that it is suitable for manufacturing an SOI laminated semiconductor substrate.

Next, as shown in FIG. 1B, polycrystalline silicon or amorphous silicon 7 is formed on the surface of the first silicon wafer 1 having an oxide film formed thereon by, for example, 0.2 μm by the CVD method. The formed thickness is determined by the final target SOI layer thickness. It should be noted that impurities (P, S
b, As, B) may be doped to adjust the resistance.

When the surface roughness (center line average roughness, 250 μm square) of the surface after forming the polycrystalline silicon or the amorphous silicon 7 or the surface after doping is larger than 10 Å, no adhesion may occur. From the viewpoint of adhesiveness, it is necessary to polish the surface of polycrystalline silicon or amorphous silicon to 10 Å or less.

The surface of polycrystalline silicon or amorphous silicon 7 is washed by SC1, SC2 or the like, or thermally oxidized to form a natural oxide film or a thermal oxide film of 100 Å or less. However, even if there is no oxide film, there is no problem because the oxide film is formed on the second silicon wafer surface. The oxide film may be formed on either one of the surfaces.

Next, as shown in FIG. 1 (c), the first
The silicon wafer 1 and the surface of the second silicon wafer 2 are brought into close contact with each other, and at 800 ° C. or higher, for example, 1200 ° C., 4
Perform heat treatment for an hour. As a result, the oxide film 4 between the second silicon wafer 2 and the polycrystalline silicon or the amorphous silicon 7 is locally shaken, recrystallization proceeds from the interface of the second silicon wafer 2, and polycrystalline silicon or amorphous silicon Is converted into a single crystal 9.

In this case, as described above, if the oxide film between the polycrystalline silicon and the amorphous silicon is thick, the oxide film will exist as a layer and will not be single crystallized.

As a result, as shown in FIG. 1 (d), 100 to 200 Å distributed in an island shape on the layer converted into single crystal 9.
There is a degree of oxide film 7a.

Next, as shown in FIG. 1 (e), the second silicon wafer 2 is ground until the island-shaped oxide film 7a is not damaged, and then the second silicon wafer 2 is treated with an amine-based solution which hardly reacts with the oxide film 7a. The silicon layer (second silicon wafer 2) is removed by polishing to expose the island-shaped oxide film 7a.

Next, as shown in FIG. 1 (f), SiO2
0.1μ using a weak alkaline slurry whose main component is
When the island-shaped oxide film 7a is removed by m polishing, the buried oxide film thickness is 1000Å and the SOI film thickness 10 is 0.1 μm.
The SOI laminated semiconductor substrate can be obtained.

Another embodiment according to the present invention will be described with reference to the drawings.

2A to 2F are sectional views showing the sequence of steps for manufacturing an SOI laminated semiconductor substrate in another embodiment of the present invention.

First, as shown in FIG. 2A, the second silicon wafer 2 is subjected to cleaning such as SC1 and SC2 cleaning or thermal oxidization or the like to form an oxide film 6 such as a natural oxide film or a thermal oxide film of about 100 Å or less. To form.

Further, an oxide film 5 of 200 Å or more is formed on the first silicon wafer 1 by thermal oxidation or CVD, for example, 1000 Å as in the previous example.

Next, as shown in FIG. 2B, polycrystalline silicon or amorphous silicon 8 is formed on the surface of the second silicon wafer 2 having an oxide film formed thereon by, for example, 0.2 μm by the CVD method. As described above, the formed thickness is determined by the final target SOI layer thickness. The polycrystalline silicon or amorphous silicon 8 may be doped with impurities (P, Sb, As, B) to adjust the resistance.

On the surface of polycrystalline silicon or amorphous silicon, cleaning such as SC1 or SC2 method or thermal oxidation is performed to form a natural oxide film or thermal oxide film of 100 Å or less. However, even if there is no oxide film, there is no problem because the oxide film is formed on the second silicon wafer surface. The oxide film may be formed on either one of the surfaces.

Next, as shown in FIG. 2C, the first
The silicon wafer 1 and the surface of the second silicon wafer 2 are brought into close contact with each other, and at 800 ° C. or higher, for example, 1200 ° C., 4
Perform heat treatment for an hour. As a result, the oxide film 6 between the second silicon wafer 2 and the polycrystalline silicon or the amorphous silicon 8 is locally broken, and the single crystal 9 is formed along the crystal of the second silicon wafer 2.

As a result, as shown in FIG. 1 (d), 100 to 200 Å distributed in an island shape on the single crystal 9 layer.
There is a degree of oxide film 7a.

Next, as shown in FIG. 2 (e), the second silicon wafer 2 is ground until the island-shaped oxide film 8a is not damaged, and then the second silicon wafer 2 is treated with an amine solution which hardly reacts with the oxide film 8a. Polishing is performed to remove the silicon layer (second silicon wafer 2) and expose the island-shaped oxide film 8a.

Next, as shown in FIG. 2 (f), SiO2
0.1μ using a weak alkaline slurry whose main component is
When the island-shaped oxide film 8a is removed by m polishing, the buried oxide film thickness is 1000Å and the SOI film 10 thickness is 0.1.
A μm SOI laminated semiconductor substrate is obtained.

[0041]

As described above, according to the present invention,
By polycrystallizing a polycrystalline silicon or amorphous silicon film through a thin oxide film and performing selective polishing, an SOI laminated semiconductor substrate with a small variation in the SOI layer thickness can be obtained, and a high quality MOS can be produced.

Further, since the present invention does not have the problem of overpolishing as in the prior art, the processing cost can be reduced.

[Brief description of drawings]

1A to 1F are cross-sectional views showing a manufacturing process of an SOI laminated semiconductor substrate according to the present invention.

2A to 2F are S according to another embodiment of the present invention.
It is sectional drawing which shows the manufacturing process of an OI laminated semiconductor substrate.

3A to 3F are cross-sectional views showing a manufacturing process of a conventional SOI laminated semiconductor substrate.

[Explanation of symbols]

 1 First Silicon Wafer 2 Second Silicon Wafer 3 Oxide Film 4 Oxide Film 5 Oxide Film 6 Oxide Film 7 Polycrystalline Silicon or Amorphous Silicon 8 Polycrystalline Silicon or Amorphous Silicon 9 Single Crystal 10 SOI Film 11 First Silicon Wafer 12 Dielectric (Oxide film) 13 Second silicon wafer 17 SOI laminated semiconductor substrate

Claims (6)

[Claims] 1. A method for manufacturing an SOI laminated semiconductor substrate, which is manufactured by directly adhering at least two semiconductor silicon wafers, wherein both the first semiconductor silicon wafer and the second semiconductor silicon wafer whose principal surfaces are mirror-polished. An oxide film is formed on the main surface, polycrystalline silicon or amorphous silicon is formed on the main surface of the first semiconductor silicon wafer or the second semiconductor silicon wafer, and the main surface of the first semiconductor silicon wafer and the second semiconductor silicon wafer are formed. The second semiconductor silicon wafer was ground and polished until the oxide film was exposed, the exposed oxide film was removed, and the surface was flattened. A method for manufacturing an SOI laminated semiconductor substrate, comprising: 2. The oxide film of the first semiconductor silicon wafer is 200 Å or more, and the oxide film thickness of the second semiconductor silicon wafer and the polycrystalline silicon or amorphous silicon surface is 100 Å or less. A method for manufacturing an SOI laminated semiconductor substrate as described above. 3. The surface roughness (center line average roughness, 250 μm square) of polycrystalline silicon or amorphous silicon is 10
The method for manufacturing an SOI laminated semiconductor substrate according to claim 1, wherein: 4. The method for manufacturing an SOI laminated semiconductor substrate according to claim 1, wherein polycrystalline silicon or amorphous silicon is doped with impurities (P, Sb, As, B). 5. The method for manufacturing an SOI laminated semiconductor substrate according to claim 1, wherein the heat treatment after adhesion is performed at 800 ° C. or higher. 6. The method for manufacturing an SOI laminated semiconductor substrate according to claim 1, wherein the polishing for exposing the oxide film is performed with an amine-based solution.