JP2608443B2 - Method for manufacturing semiconductor wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method for manufacturing a semiconductor wafer having a multilayer structure suitable for incorporating a three-dimensional integrated circuit device. A first wafer having an insulating film formed on its surface and a second having a silicon carbide film and an insulating film formed in order on a silicon substrate surface for the purpose of easily obtaining a good semiconductor wafer. Bonding the wafers so that the insulating films face each other, and then removing the silicon substrate in the second wafer to expose the silicon carbide film, and then the silicon carbide film A third wafer having the same structure as the second wafer is bonded to the surface of the third wafer so as to face the insulating film, and then the silicon substrate in the third wafer is removed to form a silicon carbide layer through the insulating film. And forming a multilayer structure of the base film.

[Industrial applications]

The present invention relates to a method for manufacturing a semiconductor wafer having a multilayer structure suitable for incorporating a three-dimensional integrated circuit device.

[Conventional technology]

Conventionally, research and development have been carried out by creating a semiconductor wafer in which single-crystal semiconductor layers and insulating layers are alternately stacked, and incorporating an integrated circuit device into each single-crystal semiconductor layer in the wafer to form a three-dimensional integrated circuit device. I have been.

The semiconductor wafer used in this case is to form a polycrystalline silicon layer on an insulating film, and then melt and recrystallize the polycrystalline silicon layer by laser annealing to form a single crystal layer. A structure having a multilayer structure by repeating is known.

[Problems to be solved by the invention]

According to the conventional technique, it is extremely difficult to form a high-quality single crystal layer over the entire surface of the wafer, and it has not yet reached a practical level.

The present invention makes it possible to easily obtain a semiconductor wafer having a large-area multilayer structure and excellent characteristics by extremely simple means.

[Means for solving the problem]

In the method for manufacturing a semiconductor wafer according to the present invention, a silicon carbide film (for example, a silicon wafer (for example, silicon dioxide film 2)) is formed on the surface of a first wafer having an insulating film (for example, silicon dioxide film 2) formed thereon. A step of bonding a second wafer on which a silicon carbide film 5) and an insulating film (for example, a silicon dioxide film 6) are sequentially formed so that the insulating films face each other; and then, in the second wafer, Removing the silicon substrate to expose the silicon carbide film, and then attaching an insulating film side of a third wafer having the same structure as that of the second wafer to a surface of the silicon carbide film so as to face each other. And removing the silicon substrate from the third wafer to form a multilayer structure of a silicon carbide film via an insulating film.

[Action]

By adopting the above-mentioned means, a semiconductor wafer having a multilayer structure having a large area and good characteristics can be easily formed by applying the completed technology, and silicon carbide has an energy band compared to silicon. -Since the gap is wide, a semiconductor device having good heat resistance can be manufactured.

〔Example〕

FIGS. 1 to 5 show cutaway side views of a main part of a wafer at important points in a process for explaining an embodiment of the present invention, and will be described with reference to these drawings.

See Fig. 1. (1) Chemical vapor deposition:
By applying the CVD method, the surface is flat,
On a ceramic substrate 1 having a thickness of, for example, 600 [μm], a silicon dioxide (SiO ₂ ) film 2 is grown to a thickness of, for example, about 4000 [Å].

Incidentally, the ceramic substrate 1 is hardly etched with a silicon etch solution, and can be replaced with a substrate of high heat resistant material, for example, the whole surface of silicon nitride (Si ₃ N
₄ ) A silicon substrate coated with a film may be used.

(2) By continuing to apply the CVD method, boron
Phosphorus silicate glass (boron phosp harus silicate gla
ss: BPSG) The film 3 is grown to a thickness of, for example, about 1000 [Å].

The wafer prepared as described above is referred to as a first wafer.

See Fig. 2. (3) Low pressure gas phase epitaxial growth (low pressure)
By applying a vapor phase epitaxy (low pressure VPE) method, a thickness of, for example, 2000
[Å] A silicon carbide (SiC) film 5 of a degree is grown.

(4) By continuously applying the CVD method, an SiO ₂ film 6 having a thickness of, for example, about 4000 [Å] and a thickness of, for example, 1000 [Å] are obtained.
BPSG films 7 are sequentially grown.

The wafer prepared as described above is referred to as a second wafer.

See FIG. 3. (5) The first wafer surface, that is, the surface of the BPSG film 3,
Abut the second wafer surface, that is, the surface of the BPSG film 7;
The first wafer and the second wafer are bonded by performing a heat treatment to perform a fusion bonding of the BPSG films 3 and 7.

The heat treatment temperature in this case varies depending on the concentration of the impurities contained in the BPSG films 3 and 7;
The temperature is appropriately selected within the range of 000 [° C.].

What is important here is that the BPSG films 3 and 7 release part of the phosphorus (P) and boron (B) contained therein into the SiO ₂ films 2 and 6 during the heat treatment. Due to this, the melting point becomes high, and it was easily melted at a low temperature by the heat treatment, but after the lamination process, it did not melt unless the temperature was further increased than at that time. This is very advantageous when performing a multi-layer bonding process or performing various heat treatments for fabricating a semiconductor device later.

See FIG. 4. (6) The silicon substrate 4 is removed by immersion in a silicon etching solution such as KOH or HF + HNO ₃ to expose the SiC film 5.

In this case, it goes without saying that the ceramic substrate 1 remains without being etched.

See FIG. 5 (7) Thereafter, the SiO ₂ film 6 side of a third wafer having the same structure as that of the above-described second wafer is bonded to the surface of the SiC film 5 so as to face each other, and is bonded to the third wafer. By removing the silicon substrate 4 in the BPSG film 7 and the SiO ₂
The SiC film 5 is formed in multiple layers via the film 6. By repeating such steps, a semiconductor wafer having a required number of layers and a multilayer structure can be obtained.

Before the step of forming the second-layer SiC film 5, it is optional to perform necessary processing on the first-layer SiC film 5 or to form various elements and parts thereof. Also, after the required multilayer structure is completed, for example, at a temperature of 1000
If a heat treatment of about [° C.] to about 1150 ° C. is performed, boron and phosphorus in the BPSG films 3 and 7 are further diffused into the SiO ₂ films 2 and 6 and averaged to increase the melting point. It is in a favorable state for the process.

FIGS. 6 to 10 show side views of essential parts of a wafer at process steps for explaining another embodiment, which will be described below with reference to these figures.

See FIG. 6. (1) By applying the CVD method, an SiO ₂ film 2 is grown to a thickness of, for example, about 1000 [Å] on the same ceramic substrate 1 as that employed in the previous embodiment.

It is to be noted that the constituent material of the substrate 1 is not limited to ceramic as described above, and that this wafer is used as the first wafer in the same manner as in the above embodiment.

See FIG. 7 (2) By applying the source pressure VPE method, a SiC film 5 having a thickness of, for example, about 2000 [Å] is grown on the silicon substrate 4.

(3) The SiO ₂ film 6 having a thickness of, for example, about 1000 [Å] is grown by continuously applying the CVD method.

Of course, the wafer created in this way is the second wafer.

See FIG. 8 (4) The surface of the first wafer, that is, the surface of the SiO ₂ film 2,
The surface of the second wafer, that is, the surface of the SiO ₂ film 6 is subjected to a hydrophilic treatment and then abutted. In a dry nitrogen (N ₂ ) atmosphere, the temperature is set to, for example, about 1000 ° C., and the time is set to, for example, Half an hour〕
The first wafer and the second wafer are bonded to each other by performing a heat treatment to a degree.

The bonding between the first wafer and the second wafer thus bonded is very strong and does not peel off.

See FIG. 9 (5) The silicon substrate 4 is removed by immersion in a silicon etching solution such as KOH or HF + HNO ₃ to expose the SiC film 5.

See FIG. 10 (7) Thereafter, the SiO ₂ film 6 side of the third wafer having the same structure as the above-described second wafer is bonded to the surface of the SiC film 5 so as to face each other, and the third wafer is bonded to the third wafer. by removing in the silicon substrate 4, as shown, through the SiO ₂ film 6
The SiC film 5 is formed in multiple layers. By repeating such steps, a semiconductor wafer having a required number of layers and a multilayer structure can be obtained.

〔The invention's effect〕

In the method of manufacturing a semiconductor wafer according to the present invention, a first wafer having an insulating film formed on a surface thereof and a second wafer having a silicon carbide film and an insulating film formed in order on a silicon substrate surface are formed. Affixing, removing the silicon substrate in the second wafer to expose the silicon carbide film, and insulating the third wafer having the same structure as the second wafer on the surface of the silicon carbide film After laminating the film sides facing each other, the silicon substrate in the third wafer is removed, and this is repeated to obtain a multilayer structure of a silicon carbide film via an insulating film.

By adopting the above-described structure, a semiconductor wafer having a large area and a multilayer structure having good characteristics can be easily formed by applying the completed technology, and silicon carbide has an energy band compared to silicon. -Since the gap is wide, a semiconductor device having good heat resistance can be manufactured.

[Brief description of the drawings]

FIGS. 1 to 5 are cutaway side views of a main part of a wafer in important parts of a process for explaining an embodiment of the present invention, and FIGS.
The drawings respectively show a cross-sectional side view of a main part of a wafer at a process point for explaining another embodiment. In the figure, 1 is a ceramic substrate, 2 is a SiO ₂ film, 3 is BP
SG film, 4 is a silicon substrate, 5 is a SiC film, 6 is a SiO ₂ film, 7
Indicates a BPSG film, respectively.

Claims (1)

(57) [Claims] 1. A first wafer having an insulating film formed on a surface thereof and a second wafer having a silicon carbide film and an insulating film formed on a silicon substrate surface in this order so that the insulating films face each other. Combining, then, removing the silicon substrate in the second wafer to expose the silicon carbide film, and then forming the same structure as the second wafer on the surface of the silicon carbide film. Forming a multilayer structure of a silicon carbide film with an insulating film interposed therebetween by removing the silicon substrate in the third wafer after bonding the insulating film side of the third wafer so as to face each other. A method for manufacturing a semiconductor wafer, comprising: