JP3206944B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device using a so-called SOI substrate in which a semiconductor crystal layer is formed on an insulating substrate. More specifically, a semiconductor crystal of the semiconductor substrate is seeded on an insulating film formed on the semiconductor substrate, and a semiconductor crystal layer is formed in an island shape by epitaxial growth.
A circuit is formed on the semiconductor crystal layer of
The present invention relates to a semiconductor device having a three-dimensional structure by growing a conductor crystal layer .

[0002] In this specification, SOI is used in the meaning of a semiconductor crystal layer on an insulating film, and is not limited to a silicon semiconductor on an insulating film, but is broadly used to include a semiconductor.

[0003]

2. Description of the Related Art S in which a semiconductor crystal layer is formed on an insulating substrate
One method of manufacturing an OI substrate is to form an opening in an insulating film formed on a semiconductor substrate and epitaxially grow a semiconductor crystal layer on the insulating film using the semiconductor crystal of the exposed semiconductor substrate as a seed.

FIG. 10 is a sectional view of a conventional SOI substrate epitaxially grown by this method. In the method of manufacturing the SOI substrate, an insulating film 22 is formed on a semiconductor substrate 21, and a part of the insulating film 22 is removed to form an opening 23. Next, when a semiconductor crystal exposed through the opening 23 is used as a seed to grow an epitaxial layer of the same kind or different kind from the semiconductor crystal, a semiconductor crystal layer 24 is formed in the opening 23 first. When the epitaxial growth is further continued, epitaxial growth is performed laterally on the insulating film 22, and the semiconductor crystal layer 24 grows on the insulating film 2.

[0005]

However, a method for obtaining an SOI substrate by a conventional lateral epitaxial growth method is as follows.
When the semiconductor crystal layer is epitaxially grown on the insulating film, the growth proceeds not only in the lateral direction but also in the vertical direction on the insulating film, so that the portion where the opening is formed is formed thick as shown in FIG. In addition, there is a problem that the thickness of the crystal layer becomes uneven. Therefore, a semiconductor crystal layer having a uniform thickness and a large area cannot be obtained.

Further, in the conventional semiconductor device, since the separation between elements is mainly performed by the pn junction, a parasitic capacitance is generated.
There are problems that hinder high-speed operation and cause a problem of latch-up.

In view of such a situation, the present invention provides an S-type semiconductor device having a semiconductor crystal layer having a flat surface and a periphery separated by an insulating film.
By forming an OI substrate , the semiconductor crystal layer
Further, a semiconductor layer can be grown via an insulating film.
Thus, it is an object to provide a semiconductor device having a three-dimensional structure .

[0008]

SUMMARY OF THE INVENTION A three-dimensional structure according to the present invention
The semiconductor device, by (a) SOI substrate of the following methods
Forming a first insulating film on the semiconductor substrate;
Forming an opening of the dummy layer is formed on the first opening and the first insulating film, said first opening and the plane
Forming a second opening at a location that is spatially separated ; forming a second insulating film over the second opening and the dummy layer;
Forming a third opening at a location adjacent to the second opening in a plane, forming the cavity by etching away the dummy layer from the third opening, and forming the cavity in the cavity. A step of epitaxially growing a semiconductor crystal layer using the semiconductor substrate as a seed; a step of removing the semiconductor crystal layer formed in the first opening to form a fourth opening;
Forming a third insulating film in the opening of (a), and removing the insulating film on the semiconductor crystal layer (b) the semiconductor of the SOI substrate
A semiconductor circuit is formed on the crystal layer, and (c) the semiconductor circuit
On the passivation film on the surface of the semiconductor layer on which
The formation of semiconductor crystal layers and semiconductor circuits
That is more semiconductor circuit a plurality of stages are formed.

[0009]

According to the present invention, a cavity is previously formed in an insulating film at a place where a semiconductor crystal layer is formed on the insulating film,
In order to epitaxially grow the semiconductor crystal layer in the cavity, the upper surface, which is the vertical growth of the epitaxial growth layer, is regulated by the insulating film and formed flat.

A dummy layer for forming a cavity is CV
Since the film can be formed by the method D, sputtering, or the like, the film thickness is easily controlled, and the epitaxial growth is performed in the cavity portion whose film thickness is sufficiently controlled, the thickness of the epitaxial growth layer can be formed very accurately.

Further, since the opening formed by removing the upper part of the seed portion of the semiconductor crystal layer is filled with the insulating film, the periphery and the bottom surface of the semiconductor crystal layer can be completely separated by the insulator. .

As a result, the SOI obtained by this method
When a semiconductor device is formed using a substrate, each element can be formed in each island-shaped semiconductor region, each element can be completely electrically isolated, and the occurrence of parasitic capacitance can be prevented. Therefore easily achieve high-speed operation, when applicable to high frequency device co
In addition, a high-performance semiconductor device having a three-dimensional structure can be obtained.
You .

[0013]

Next, the present invention will be described in detail with reference to the drawings. Figure 1-9 shows an embodiment of the present invention half
It is process explanatory drawing which shows the method of manufacturing the SOI substrate part of a conductor device .

First, as shown in the step of FIG. 1, a first opening 3 is formed by removing a part of a first insulating film formed on a semiconductor substrate. As a specific example, the (100) plane silicon substrate 1 was thermally oxidized at a substrate temperature of about 1000 ° C. to form a 100 nm-thick first silicon oxide film 2 as a first insulating film. Next, a part of the first silicon oxide film 2 was removed by an ordinary photoresist process to form a first opening 3 and a part of the silicon substrate 1 was exposed.

Next, as shown in the step of FIG. 2, after forming a dummy layer on the entire surface of the first insulating film, a part of the dummy layer around the seed portion (first opening) is removed. The second opening 5 is formed. As a specific example, the silicon substrate 1 having the first opening 3 formed in the previous process is put into a reaction furnace, the substrate temperature is set to 400 ° C., a silane (SiH ₄ ) gas is introduced, and plasma CVD is performed for 60 minutes. A silicon layer 4 was deposited on the entire surface of the silicon substrate 1 to a thickness of 200 nm. Next, the surface of the amorphous silicon layer 4 is made flat by etching back, and a part of the amorphous silicon layer 4 adjacent to the first opening is etched by a reactive ion etching (hereinafter, referred to as RIE) method in a photoresist step. Selective etching using carbon fluoride (CF ₄ ) gas and chlorine (Cl ₂ ) gas to form a second opening 5,
The first silicon oxide film 2 was exposed.

Next, as shown in the step of FIG. 3, after forming a second insulating film on the entire surface of the dummy layer, part of the second insulating film around the second opening is removed. 3 opening 7
To form As a specific example, a silane (SiH ₄ ) gas and a nitrogen oxide (N ₂ O) gas are introduced and a gas phase reaction is performed at 800 ° C. to form a second silicon oxide film 6 as a second insulating film.
Was deposited at 400 nm. At this time, the second silicon oxide film 6
Is also formed inside the second opening 5, so that the first silicon oxide film 2 and the second silicon oxide film 6 are connected. Thereafter, a portion of the second silicon oxide film 6 adjacent to the second opening and corresponding to an end portion of the amorphous silicon layer 4 is removed by corrosion to form a third opening 7 to form the amorphous silicon layer. Part 4 was exposed. The third opening 7 is located at a distance from the first opening as a seed portion.
It was formed at a place of μm.

Next, as shown in FIG.
Then, the dummy layer 4 is etched away to form a cavity 8 for epitaxially growing a semiconductor crystal layer described later. As a specific example, when hydrogen chloride gas was introduced into the reaction furnace at room temperature, only the amorphous silicon layer 4 was etched and removed sequentially from the third opening 7 to form a cavity 8. The silicon semiconductor substrate 1 side of the cavity 8 coincided with the first opening 3 described above, and the silicon semiconductor substrate 1 was exposed.

Next, as shown in FIG. 5, the semiconductor substrate exposed by the cavity 8 is used as a seed to epitaxially grow inside the cavity to form a semiconductor crystal layer. As a specific example, 0.15 sccm of disilane (Si ₂ H ₆ ) and acetylene (C ₂ H
₂ ) In addition to 0.15 sccm, a mixture of 3 slm of hydrogen (H ₂ ) gas as a carrier gas and 10 sccm of hydrogen chloride (HCl) gas as an etchant was used, and the substrate surface was heated at 1350 ° C. for 10 minutes. Was reacted. At this time, the vapor growth gas enters the inside of the cavity 8 through the third opening 7, and epitaxial growth is performed using the exposed surface of the silicon semiconductor substrate 1 in the cavity 8 as a seed, and a silicon carbide (SiC) crystal layer is formed in the cavity 8. 9 was formed. At this time, since the second silicon oxide film 6 above the cavity 8 regulates the vertical epitaxial growth, the upper part of the silicon carbide crystal layer 9 is made flat. Here, when epitaxial growth is performed by adjusting the flow ratio of the vapor growth gas, the epitaxial growth is not performed on the surface of the second silicon oxide film 6 but only from the silicon substrate. That is, during epitaxial growth, the second
Is deposited on the surface of the silicon oxide film 6, but because of poor adhesion, it is not etched and deposited by the hydrogen chloride gas in the mixed gas, and the portion grown from the silicon substrate is not etched with good adhesion. The growth proceeds. Therefore, the flow ratio of hydrogen chloride is determined to meet this purpose.

Next, as shown in FIGS. 6 and 7, the semiconductor crystal layer formed in the first opening is removed, and a fourth opening 12 is formed. As a specific example, silane (Si
H ₄ ) gas and nitrogen oxide (N ₂ O) gas are introduced to 75
A gas phase reaction is performed at 0 to 850 ° C. to form a silicon oxide film 10 of 1 μm.
Deposited. Next, a portion of the silicon oxide film 10 above the seed portion (the first opening 3) is etched and removed by a photoresist process to form an opening 11 to form a portion on the seed portion (the first opening 3). The silicon carbide crystal layer 9 was exposed (see FIG. 6).

Next, as shown in FIG. 7, carbon fluoride (CF) is used as an etchant (used gas) by RIE.
₄ ) The whole surface was removed by ion etching using oxygen (O ₂ ) to form a fourth opening 12. Thereby, silicon carbide crystal layer 9 on the seed portion is removed, and semiconductor substrate 1 is exposed.
And completely separated. During the etching by the RIE method, the silicon oxide film 10 is also etched.

Next, as shown in FIGS. 8 and 9, after a third insulating film is formed in the fourth opening 12, the insulating film on the surface of the semiconductor crystal layer 9 is removed to form a semiconductor substrate. As a specific example, a silane (SiH ₄ ) gas and a nitrogen oxide (N ₂ O) gas are introduced by a CVD method, and the substrate temperature is 750 to 80.
Under a condition of 0 ° C., a third silicon oxide film 13 was deposited to a thickness of 100 nm to cover the surface.

Thereafter, wet etching was performed by using a mask (above the seed portion) in a photoresist process to remove the silicon oxide films 10 and 13 on the surface of the semiconductor crystal layer 9 to expose the semiconductor crystal layer. At this time, by leaving the third silicon oxide film 13 around the silicon carbide crystal layer 9 as it is, it can be used for element isolation in the vertical and horizontal directions.

As described above, a flat semiconductor crystal layer is obtained on the insulating film as shown in FIG. 9, and the formation of the SOI substrate in which the semiconductor region is separated into islands by the insulator is completed. Note that the thickness of the semiconductor crystal layer is determined by the thickness of the amorphous semiconductor layer, and the thickness of the amorphous semiconductor layer is relatively easily controlled, so that the thickness of the semiconductor crystal layer can be relatively easily controlled.

In the above embodiment, an example has been described in which amorphous silicon is deposited as a dummy layer to form a cavity and the amorphous silicon is corroded and removed after forming an insulating film. However, this method is not limited to amorphous silicon.

That is, any material can be used as long as it is easy to deposit and can remove only this layer without corroding the insulating film or semiconductor substrate later. Instead, another amorphous semiconductor layer such as an amorphous silicon carbide layer, a silicon nitride film, an aluminum film, or the like can be used. In the case of an aluminum film, steps must be left at the time of film formation, the insulating film on the aluminum film must be able to be formed at a low temperature, and the seed portion must not be damaged. There are problems, but they can be used satisfactorily if these are overcome.

When a silicon nitride film is used, silane (SiH ₄ ) gas and ammonia (N
A flat layer can be formed by gas phase reaction at 350 ° C. by introducing H ₃ ) gas, and hot phosphoric acid is used to remove corrosion by using hot phosphoric acid without corroding other insulating films. Only the film can be removed by corrosion.

When a nitride film is used as an insulating film,
A silicon oxide film can also be used as a material for forming a cavity.

Further, in the above-mentioned specific embodiment, the example in which silicon carbide is used as the semiconductor crystal layer has been described. However, other semiconductor crystal layers such as silicon can be similarly formed.

A semiconductor device incorporating an integrated circuit can be obtained by using a SOI substrate in which a semiconductor region is formed in an island shape by the above-described method and forming a semiconductor circuit in the semiconductor region by a normal process. In this case, since each element is completely separated by an insulator, no parasitic capacitance occurs between the elements or between the element and the substrate, and no latch-up problem occurs.

Further, by flattening the passivation film on the surface of the semiconductor device manufactured as described above and growing a semiconductor crystal layer by the same method as described above, a semiconductor circuit can be formed on the second floor portion. By repeating this method further, a plurality of stages can be formed, a semiconductor device having a three-dimensional structure can be obtained, and higher integration of elements can be achieved.

In this case, by forming a step of a silicon crystal layer and a step of a silicon carbide crystal layer in each step, a semiconductor having a composite three-dimensional structure having elements utilizing characteristics of the respective semiconductor crystal layers is formed. A device can also be formed.

[0032]

As described above, according to the present invention,
A cavity is formed by a second insulating film on an insulating film of a semiconductor substrate, and a semiconductor crystal layer is epitaxially grown in the cavity. Therefore, vertical epitaxial growth is restricted by the upper wall of the cavity, and lateral epitaxial growth is performed. A semiconductor crystal layer having a flat upper surface can be formed on an insulating film, and a highly accurate circuit can be formed.

Further, according to the present invention, since an amorphous semiconductor layer, a silicon nitride film, or the like is formed and formed into a cavity to form a cavity, it is relatively easy to control the thickness of the cavity, and the film is formed on the insulating film. There is an effect that a semiconductor crystal layer having an accurate thickness can be formed.

Further, since the semiconductor crystal layer above the seed portion is removed and an insulating film is formed in the opening, the element formation region of the semiconductor crystal layer is completely electrically connected to other semiconductor regions and the semiconductor substrate. It is possible to prevent the occurrence of the parasitic capacitance and the latch-up problem, to speed up the device operation, and to improve the performance as a high-frequency device.

[Brief description of the drawings]

FIG. 1 illustrates an S used in a semiconductor device according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 2 illustrates an S used in a semiconductor device according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 3 illustrates a semiconductor device according to an embodiment of the present invention;
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 4 is a diagram illustrating a semiconductor device according to an embodiment of the present invention;
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 5 illustrates an S used in a semiconductor device according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 6 illustrates an S used in a semiconductor device according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 7 illustrates a semiconductor device according to an embodiment of the present invention;
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 8 illustrates an S used in a semiconductor device according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 9 shows S used in a semiconductor device according to an embodiment of the present invention.
It is a final process explanatory view which shows the manufacturing process of the manufacturing method of an OI board.

FIG. 10 is an explanatory sectional view of an SOI substrate manufactured by a conventional epitaxial growth method.

Claims (3)

(57) [Claims] (1) An SOI substrate is formed by the following method.
Made is, a first insulating film formed on a semiconductor substrate, forming a first opening, a dummy layer is formed on the first opening and the first insulating film, said first Planely separated from the opening
Place in a step of forming a second opening, the second insulating film is formed on the second opening and the dummy layer, the second
Seed forming a third opening in the opening and the planar contiguous location, the steps of the dummy layer from the third opening to form a cavity is etched away, the semiconductor substrate in the cavity the semiconductor crystal layer formed epitaxially growing, a step of forming a fourth opening to remove the semiconductor crystal layer formed on the first opening, a third insulating film on the fourth opening as, wherein comprising a step of removing the insulating film on the semiconductor crystal layer method (b) a semiconductor circuit on a semiconductor crystal layer of the SOI substrate form
Made is, (c) path of the surface of said semiconductor layer which semiconductor circuits are formed
A semiconductor crystal layer and a semiconductor layer are further formed on the passivation film.
The formation of a circuit leads to the formation of multiple stages of semiconductor circuits.
Semiconductor device having a three-dimensional structure . 2. The three-dimensional semiconductor device according to claim 1, wherein said semiconductor crystal layer is a silicon crystal layer or a silicon carbide crystal layer. 3. A semiconductor device having a three-dimensional structure of the multi-stage semiconductor crystal layer formed by mixing the stepped stage between the silicon carbide crystal layer of the silicon crystal layer according to claim 1 or 2 wherein.