JP2001093887A - Method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hollow in a substrate with satisfactory controllability. SOLUTION: This method comprises a thin film accumulating step for accumulating a thin film on a semiconductor substrate (a), a thin film opening step for forming an opening at the thin film, by removing one part of the thin film and exposing the semiconductor substrate (b), a groove forming step for forming a groove having an opening which is not larger than the opening at the semiconductor substrate by removing one part of the exposed semiconductor substrate (d), and a heat treatment step for carrying out heat treatment to the groove and closing the opening of the groove (e).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, and more particularly, to a method of forming a cavity in a substrate by using a thin film for suppressing surface diffusion of substrate atoms. The present invention relates to a technique for manufacturing with good controllability and greatly reducing labor and time required for manufacturing a cavity.

[0002]

2. Description of the Related Art With the rapid progress of semiconductor device manufacturing technology in recent years, MOS transistors have been rapidly miniaturized.
It has become possible to develop more compact and lightweight electronic devices. However, on the other hand, one of the problems that the short channel effect caused by the decrease in the distance between the source and the drain of the MOS transistor cannot be ignored. Since the short channel effect greatly affects the electrical characteristics of the semiconductor device, such as changing the threshold voltage of the semiconductor device, it is required to manufacture a semiconductor device in which the short channel effect is suppressed.

[0003] Against this background, recently, the source /
In order to make the impurity profile in the drain region shallower and to form a steep impurity profile to suppress the short channel effect, the semiconductor device is manufactured at a lower temperature than before, or impurity ion implantation is performed at a lower acceleration voltage. Various countermeasures have been taken.

[0004] Among these various countermeasures, recently, as disclosed in Japanese Patent Application Laid-Open No.
Forming a groove under the channel region of the transistor,
It has been clarified that the short channel effect can be suppressed by heat-treating the formed groove, closing the opening of the groove, and forming a cavity below the channel region. I am collecting.

[0005]

However, up to now, a method of manufacturing a semiconductor device in which a cavity is formed below a channel region to suppress a short channel effect has the following technical problems to be solved. is there.

First, generally, in order to effectively suppress the short channel effect, the cavity in the substrate and the channel region above the cavity in the substrate are controlled with good control, such as controlling the position of the cavity in the substrate in the depth direction. Although it is important to fabricate the semiconductor device, in the conventional method of manufacturing a semiconductor device, irregularities occur on the surface of the semiconductor device after the cavity is formed due to the variation in the depth of the groove formed when the cavity is formed. Resulting in.

Second, the conventional method for manufacturing a semiconductor device requires a great deal of labor and time to form a cavity, such as a long time required for heat treatment for closing a groove.
It has been difficult to efficiently manufacture a semiconductor device.

The present invention has been made in view of the above technical problems, and an object of the present invention is to manufacture a semiconductor device in which a cavity is formed in a substrate with good controllability and the labor and time required for forming the cavity are greatly reduced. It is to provide a method.

[0009]

Means for Solving the Problems In order to solve the above technical problems, the present inventors have deposited a thin film having an opening on a substrate to suppress surface diffusion of substrate atoms, After forming a groove such as a trench having the same size or smaller opening as the opening in the substrate, heat treatment is performed on the groove to form a cavity inside the substrate with good controllability, and the labor required for forming the cavity And that it is possible to significantly reduce time.

A first feature of the present invention based on the above idea is that in a method of manufacturing a semiconductor device having a cavity in a semiconductor substrate, a thin film deposition step of depositing a thin film on the semiconductor substrate, Forming a thin film opening by exposing the semiconductor substrate by removing a part of the semiconductor substrate, and removing an exposed part of the semiconductor substrate to have an opening equal to or smaller than the opening. A semiconductor device manufacturing method includes a groove forming step of forming a groove in a semiconductor substrate, and a heat treatment step of applying a heat treatment to the groove to close an opening of the groove.

According to the above structure, a thin film for suppressing surface diffusion of substrate atoms is deposited near the groove, and only the exposed region is deformed by surface diffusion without deforming the substrate in a region in contact with the thin film. The cavity can be formed inside the substrate with good controllability, and the labor and time required for producing the cavity can be greatly reduced.

It is preferable to perform the groove forming step after depositing the second thin film on at least the side wall of the opening of the thin film. Thus, a groove having an opening smaller than the opening of the groove can be easily formed, and the labor and time required for forming a cavity can be significantly reduced.

The area of the opening of the thin film is one of that of the groove.
It is desirable that it is not less than twice and not more than 9 times. Thereby, since the vicinity of the opening can be closed first during the heat treatment,
Even when the depth of the groove varies, it is possible to suppress the unevenness of the unevenness on the outermost surface of the substrate, and the flatness of the substrate surface is not deteriorated.

Further, the thin film is preferably a single-layer film or a laminated film. This allows the thin film to be physically large
Since there is no chemical change, the change in the shape of the groove can be controlled, and the cavity can be easily formed.

On the other hand, a second feature of the present invention is that in a semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, a cross-sectional area of a bottom of the semiconductor substrate is 1.2 times that of an opening. The present invention is directed to a semiconductor device manufacturing method including a groove forming step of forming an inversely tapered groove and a heat treatment step of applying heat treatment to the groove to close an opening of the groove.

According to the above configuration, the vicinity of the opening of the groove can be closed first during the heat treatment, so that the cavity can be formed in a shorter time.

According to a third feature of the present invention, in a semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, a groove forming step of forming a groove in the semiconductor substrate, at least a bottom or a groove of the groove is provided. A thin film deposition step of depositing a thin film on a lower side wall of the semiconductor device, and a heat treatment step of applying heat treatment to the groove to close an opening of the groove.

According to the above configuration, the shape change at the lower portion of the groove can be suppressed by the thin film, and the shape can be changed only near the opening of the groove, so that the cavity can be formed inside the substrate with good controllability. it can.

Here, it is desirable to use a silicon substrate as the semiconductor substrate and a silicon oxide film or silicon nitride film as the thin film.

A fourth feature of the present invention is a method of manufacturing a semiconductor device having a cavity in a semiconductor substrate, wherein a thin film having a melting point lower than the melting point of the semiconductor substrate is deposited on the semiconductor substrate. A semiconductor device manufacturing method comprising: a thin film deposition step; a groove forming step of forming a groove by removing a part of a thin film and a semiconductor substrate; and a heat treatment step of applying heat treatment to the groove to close an opening of the groove. It is in.

According to the above configuration, a cavity can be formed in the substrate in a shorter time.

In this case, the semiconductor substrate is preferably a silicon substrate, and the thin film is preferably a SiGe thin film.

The thickness of the thin film is preferably 10% or more of the size of the opening diameter of the groove.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device manufacturing method according to the present invention
It was invented based on the knowledge extracted by vigorous experiments. Therefore, before describing details of the semiconductor device manufacturing method according to the embodiment of the present invention, FIGS.
The contents of this experiment will be described with reference to FIG.

The inventors of the present invention propose a method of manufacturing a semiconductor device for forming a cavity with good controllability and greatly reducing the labor and time required for forming the cavity, and suppress the surface diffusion of substrate atoms on the substrate. For depositing a thin film having an opening, and having a groove such as a trench having the same size or smaller opening as the thin film opening in the substrate,
It was proposed that the grooves be subjected to heat treatment. Then, in order to narrow down the adequacy of the manufacturing method and the manufacturing conditions, (1) when the opening diameter of the thin film is equal to the opening diameter of the groove,
(2) For two cases where the opening diameter of the thin film is larger than the opening diameter of the groove, the substrate on which the thin film is deposited is modeled, and the movement of the substrate atoms is investigated using the surface diffusion equation.
The shape change of the groove was analyzed. The results of the analysis are shown below.

First, an analysis result in the case where the opening diameter of the thin film is equal to the opening diameter of the groove will be described.

FIG. 9 shows how the shape of the groove changes with the progress of the heat treatment when the opening diameter of the thin film is equal to the opening diameter of the groove.
Here, the ratio of the depth of the groove to the length of the opening diameter of the groove (hereinafter referred to as the aspect ratio) was set to 10.

From the figure, when the opening diameter of the thin film 90 is equal to the opening diameter of the groove, after the heat treatment time T = 6.0T0, constriction occurs at the lower part of the groove (FIG. 9B), and the heat treatment further proceeds. At time T = 10.5T0, constriction occurs at the upper part of the groove (FIG. 9C). FIG.
As shown in (d), when the depths of the grooves are different (x = d
1, d2, d3, d4), a cavity of almost the same size is formed at the bottom of the groove, and the time until the cavity is formed is about the same as 6.0T0 to 6.6T0. Was found. Note that T0 used in this specification indicates a unit of time, for example, a value of several seconds to several minutes. Further, T0 is a value that depends on the type of atmosphere, pressure, temperature, and surface diffusion coefficient at the time of heat treatment. Therefore, when the heat treatment conditions such as the type of atmosphere, pressure, and temperature are the same, a cavity is formed via T0. You can make a direct comparison of the time taken.

To summarize the above, as shown in FIG.
When the opening diameter of the thin film is the same as that of the groove, cavities can be formed in order from the bottom of the groove, and when the depth of the groove is not deep, one cavity is formed. It was found that it was possible. On the other hand, it has also been found that when there is a variation in the depth of the groove, the position of the constriction and the surface shape of the outermost surface vary, and in extreme cases, the number of cavities to be formed changes. In such a case,
Even if the substrate surface is flattened by a process such as depositing an epitaxial film on the substrate, it is expected that it is difficult to effectively suppress the short-channel effect because the positions of the cavities themselves have already varied. You. However, it can be said that the effect of suppressing the depression on the outermost surface of the substrate can be obtained to some extent.

Next, an analysis result in the case where the opening diameter of the thin film is larger than the opening diameter of the groove will be described.

FIGS. 11A and 11B show how the shape of the groove changes with the progress of the heat treatment when the opening diameter of the thin film is larger than the opening diameter of the groove. Here, it is assumed that the opening diameter Rm of the thin film and the opening diameter R0 of the groove have a relationship of Rm = 1.25R0.

As can be seen from the drawing, when the opening diameter of the thin film is made larger than the opening diameter of the groove, the groove is formed regardless of the depth of the groove before the heat treatment, unlike the case where the opening diameter of the thin film is equal to the opening diameter of the groove. It can be seen that it closes near the upper opening. Further, even when the opening diameters of the thin films are different (Rm = 2R0, 3R0, 5R0), the same tendency was confirmed as shown in FIG.

To summarize the above, when the opening diameter of the thin film is larger than the opening diameter of the groove, the groove can be closed near the opening of the groove and a cavity can be formed, so that the depth of the groove varies. Even in this case, it was found that the shape of the outermost surface of the substrate did not vary, and the position of the cavity itself did not vary significantly (see FIG. 12).

To summarize the above two analysis results, in order to form a cavity with good controllability and to greatly reduce the labor and time required for cavity production, (1) a thin film having an opening on a substrate Depositing, (2) forming a groove in the substrate having an opening of the same size or smaller than the opening of the thin film;
It became clear that it is better to make the opening diameter of the thin film larger than the opening diameter of the groove. The significance of making the opening diameter of the thin film larger than the opening diameter of the groove in (3) lies in exposing the corners of the substrate. By exposing the corners of the substrate, a change in the shape of the substrate occurs in the direction of reducing the non-uniformity of the curvature of the substrate in the vicinity of the opening of the groove, and there is an advantage that the opening of the groove is closed first. It is. On the other hand, when the opening diameter of the thin film is equal to the opening diameter of the groove, the curvature of the substrate near the opening of the groove becomes almost uniform, and the shape change in this vicinity is less likely to occur. It will not close. When the opening diameter of the thin film is equal to the opening diameter of the groove, the above advantages cannot be expected, but there are also advantages such as suppression of depression on the outermost surface of the substrate. Making the opening diameters of the grooves equal will also be effective.

Finally, the result of analyzing the time from the start of the heat treatment when the thin film material is placed near the opening of the groove to the closing of the groove is shown.

FIG. 13 shows the relationship of the time until the vicinity of the opening closes due to the change in the opening diameter of the thin film. Here, the aspect ratio was set to 10.

From the figure, it can be seen that the opening diameter Rm of the thin film is 5R0, 2R
It can be seen that the time until the opening of the groove closes becomes shorter as it becomes smaller as 0 or 1.25R0. Therefore, it can be said that the smaller the opening diameter of the thin film (closer to the opening diameter of the groove), the more efficiently the cavity can be formed. However, if the opening diameter of the thin film is too small, as described above, the driving force for the corners of the substrate to be rounded becomes small, and the opening of the substrate cannot be closed. It can be said that it is desirable to make the opening diameter about 1.1 times or more of the opening diameter.

The above is the knowledge obtained by computer experiments (or simulations or analysis using the surface diffusion equation) performed by the inventors. So, below,
With reference to FIGS. 1 to 8, a method of manufacturing a semiconductor device according to an embodiment of the present invention based on the knowledge obtained from the above experiment will be described in detail. Note that the following description will be made on the assumption that a silicon substrate is used as the “semiconductor substrate”, but the technical scope of the present invention is not limited to this. For example, a germanium substrate or the like, which is the same semiconductor, may be used.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 5 is a sectional process view showing the method for manufacturing a semiconductor device according to the embodiment.

In the method of manufacturing a semiconductor device according to the first embodiment of the present invention, (a) first, after forming the thin film 11 on the substrate 12,
A resist film 10 is formed on the thin film 11. Here thin film 1
The materials of (1) are (1) good adhesion to the substrate and do not react with the substrate, (2) the whole or a part of the thin film is difficult to be reduced by hydrogen, (3) flow, chemical change and volume change are difficult. 4) heat resistance, (5) high mechanical strength,
Use one that satisfies conditions such as As a material satisfying such conditions, for example, a single film layer of a silicon nitride film, a laminated film including a single film layer of a silicon nitride film, and the like can be considered.
Note that as the stacked film including the silicon nitride film, a stacked film having a two-layer structure in which a silicon nitride film is deposited on a silicon oxide film is preferably used.

(B) Next, using the resist film 10 as a mask, the region A of the thin film 11 is anisotropically etched and removed by a method such as reactive ion etching (hereinafter referred to as RIE).

(C) Subsequently, using the thin film 11 as a mask,
The region B of the substrate 12 is anisotropically etched by a method such as RIE, and at the same time, the resist film 1 is etched by ashing.
Remove 0. As a result, a groove can be formed in the substrate. In this specification, the term “groove” refers to a trench,
Alternatively, it means both elongated grooves such as space portions of a line and space pattern.

(D) Next, the vicinity C of the opening of the thin film 11 is retreated so that the opening diameter of the thin film 11 is larger than that of the groove. In the method for manufacturing a semiconductor device according to the first embodiment of the present invention, the opening diameter of the thin film is equal to the opening diameter of the groove being equal to 1.
When converted to an area of about 2 to 3.0, the thin film 11 is retreated so that the opening area of the mask is 1.4 to 9.0 times that of the groove. Here, when a thin film 11 having a two-layer structure in which a silicon nitride film is laminated on a silicon oxide film is used, the silicon oxide film and the silicon nitride film may be, for example, hydrofluoric acid and hot phosphoric acid, respectively. It is good to retreat using. Note that the retreat amount at that time is controlled by time control.

(E) Subsequently, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 13 inside the substrate.

(F) Finally, the thin film 11 on the substrate 13 is removed.

By the above-described series of processing steps, a cavity can be formed with good controllability, and the labor and time required for forming the cavity can be greatly reduced. On the other hand, when flattening the substrate surface on which the cavities are formed by the above-described processing, FIG.
As shown in the figure, first, an amorphous silicon layer is deposited and crystallized on a substrate, or after an epitaxial layer is deposited, a method such as chemical mechanical polishing is used to flatten the substrate surface. good.

When the thin film 11 is a laminated film,
As shown in FIG. 3, the opening diameter of the thin film 11 may be made larger than that of the groove by a method. (A) First, the thin film 32 is formed on the substrate 33, and then the thin film 31 is deposited on the thin film 32. Next, a resist film 30 is formed on the thin film 31.

(B) Next, using the resist film 30 as a mask, the thin film 31 and the thin film 3 are formed by a method such as RIE.
The region A of No. 2 is anisotropically etched and removed.

(C) Subsequently, using the thin film 31 and the thin film 32 as a mask, the region B of the substrate 33 is anisotropically etched by a method such as an RIE process to form a groove in the substrate, and at the same time, a register is formed by an ashing process or the like. The film 30 is removed.

(D) Next, the vicinity C of the opening of the thin film 32 is retracted so that the opening diameter of the thin film 32 is larger than that of the groove.

(E) Subsequently, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 34 inside the substrate.

(F) Finally, the thin films 31 and 32 on the substrate 33 are removed.

According to the above-described processing steps, physical and chemical changes such as etching of the substrate from above the thin film 31 and the thin film 32 can be suppressed, so that the semiconductor device manufacturing process can be executed with good controllability. It becomes possible.

The process for making the opening diameter of the thin film 11 larger than that of the groove may be performed by a method as shown in FIG. (A) First, the thin film 41 is formed on the substrate 42,
A resist film 40 is formed on the thin film 41.

(B) Next, after the thin film 41 is anisotropically etched by a method such as RIE using the resist film 40 as a mask, a side wall 43 is formed on the side of the thin film 41. After that, the resist film 40 is removed. The side wall 43 may be formed by, for example, forming a silicon nitride film on the entire surface of the substrate and then performing anisotropic etching on the silicon nitride film.

(C) Subsequently, using the thin film 41 and the side wall 43 as a mask, the region A of the substrate 42 is anisotropically etched by a method such as RIE to form a groove.

(D) Next, by removing the side wall 43, a thin film layer having an opening diameter larger than the opening diameter of the groove is formed. When a semiconductor material having a lower melting point than the substrate, such as SiGe, is used as the material of the side wall 43, this processing step can be omitted.

(E) Subsequently, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 44 inside the substrate.

(F) Finally, the thin film 41 on the substrate 42 is removed.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 5 is a sectional process view showing the method for manufacturing a semiconductor device according to the embodiment.

In the method for manufacturing a semiconductor device according to the second embodiment of the present invention, (a) first, a resist film 50 is formed on a substrate 51.

(B) Next, using the resist film 50 as a mask, the region A of the substrate 51 is anisotropically etched by a method such as RIE to form a groove. At this time, the groove is formed such that the lower portion of the groove has an inverted tapered shape having a larger cross-sectional area than the opening of the groove. Specifically, the maximum value of the cross-sectional area of the groove is set to be at least 1.2 times the area of the opening of the groove.

(C) Subsequently, the resist film 50 is removed by an ashing process or the like.

(D) Finally, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 52 inside the substrate 51.

According to the method of manufacturing a semiconductor device according to the second embodiment of the present invention, the cavity can be formed in a shorter time because the sectional area of the groove becomes smaller as approaching the opening. Furthermore, it is possible to flatten the substrate surface by performing the surface flattening process used in the semiconductor device manufacturing method according to the first embodiment of the present invention. A cavity can be formed with good controllability.

(Third Embodiment) FIG. 6 shows a third embodiment of the present invention.
FIG. 5 is a sectional process view showing the method for manufacturing a semiconductor device according to the embodiment.

In the method for manufacturing a semiconductor device according to the third embodiment of the present invention, (a) first, a resist film 60 is formed on a substrate 61.

(B) Next, using the resist film 60 as a mask, the region A of the substrate 61 is anisotropically etched by a method such as RIE to form a groove. Thereafter, the resist film 60 is removed by ashing or the like.

(C) Subsequently, a thin film 62 is deposited on the substrate surface. Here, it is desirable to use a silicon oxide film or a silicon nitride film as the thin film 62. It should be noted that when a silicon oxide film is used for the thin film 62, it is reduced during the heat treatment and the silicon oxide film may not remain in the cavity.

(D) Next, the region B of the thin film 62 is etched leaving the side wall of the groove.

(E) Subsequently, a second material 63 is deposited inside the groove. Here, it is desirable to use a photosensitive resin or the like as the second material 63.

(F) Subsequently, using the second material 63 as a mask, the thin film 62 (region C) on the side wall above the groove is removed.

(G) Next, the second material 63 is removed.

(H) Finally, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 63 inside the substrate 61.

According to the method of manufacturing a semiconductor device according to the third embodiment of the present invention, since the thin film 62 for suppressing surface diffusion of substrate atoms is formed below the groove, a change in shape at the lower part of the groove is suppressed. It is possible to cause a shape change only on the upper side of the groove, and it is possible to control the cavity forming process such as the shape of the cavity. Furthermore, it is possible to flatten the substrate surface by subjecting the substrate to the surface flattening treatment used in the semiconductor device manufacturing method according to the first embodiment of the present invention, and the opening diameter is smaller than that of the groove. If a large thin film is deposited on the substrate surface, a cavity can be formed at higher speed and with better controllability. The method for manufacturing a semiconductor device according to the third embodiment of the present invention will be most effective when the cavity to be formed is not spherical but vertically long.

Here, as an application example of the semiconductor device manufacturing method according to the third embodiment of the present invention, as shown in FIG.
The thin film 70 is formed only at the lower part of the groove or only at the lower part and under the side wall.
May be formed. In this case, the second material 72
By controlling the deposition amount of the thin film 70 on the side portion,
To control the height.

(Fourth Embodiment) FIG. 8 shows a fourth embodiment of the present invention.
FIG. 5 is a sectional process view showing the method for manufacturing a semiconductor device according to the embodiment.

In the method of manufacturing a semiconductor device according to the fourth embodiment of the present invention, (a) first, a mixed crystal 81 of Si and Ge, which is a thin film having a lower melting point than silicon, is formed on a substrate 82. Membrane, and
A resist film 80 is formed thereon.

(B) Next, using the resist film 80 as a mask, the SiGe film 81 and the region A of the substrate 82 are anisotropically etched by a method such as RIE to form a groove.

(C) Subsequently, the resist film 80 is removed by an ashing process or the like.

(D) Finally, the groove is subjected to a heat treatment in a non-oxidizing atmosphere to close the opening of the groove and form a cavity 83 inside the substrate 82.

According to the semiconductor device manufacturing method according to the fourth embodiment of the present invention, since the heat treatment is performed using a thin film having a lower melting point than the substrate, the cavity can be formed in a shorter time. Further, the surface of the substrate can be flattened by subjecting the substrate to the surface flattening process used in the semiconductor device manufacturing method according to the first embodiment of the present invention. If a larger thin film is deposited on the substrate surface, a cavity can be formed at a higher speed and with better controllability.

The thickness of the SiGe thin film is preferably set to 10% or more of the size of the opening diameter of the groove.

As described above, it is to be fully understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention must be limited only by the matters specifying the invention according to the claims that are reasonable from this disclosure.

[0085]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the thin film material for suppressing the surface diffusion of the substrate atoms is arranged near the opening of the groove to the entire substrate. Since the heat treatment is performed, the cavity can be formed inside the substrate with good controllability, and the labor and time required for producing the cavity can be greatly reduced.

According to the method of manufacturing a semiconductor device of the present invention, by exposing the corners of the substrate, the shape change of the substrate in the direction of reducing the non-uniformity of the curvature of the substrate in the vicinity of the opening of the groove is achieved. As a result, the merit that the opening of the groove is closed first is obtained, so that the cavity can be formed inside the substrate with good controllability, and the labor and time required for producing the cavity can be greatly reduced.

Further, according to the method of manufacturing a semiconductor device of the present invention, the cavity can be formed in a shorter time because the sectional area of the groove becomes smaller as approaching the opening.

Further, according to the method of manufacturing a semiconductor device of the present invention, since a thin film for suppressing surface diffusion of substrate atoms is formed on the side wall of the groove, a change in shape on the side wall of the groove is suppressed.
It is possible to cause a shape change only on the upper side of the groove, and it is possible to control the cavity forming process such as the shape of the cavity.

Further, according to the semiconductor device manufacturing method of the present invention, since the heat treatment is performed using a thin film having a lower melting point than the substrate, the cavity can be formed in a shorter time.

[Brief description of the drawings]

FIG. 1 is a sectional process view illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a sectional process view showing a substrate surface flattening process according to the embodiment of the present invention.

FIG. 3 is a sectional process view showing an application example of the semiconductor device manufacturing method according to the first embodiment of the present invention.

FIG. 4 is a sectional process view showing an application example of the semiconductor device manufacturing method according to the first embodiment of the present invention.

FIG. 5 is a sectional process view showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 6 is a sectional process view showing a method for manufacturing a semiconductor device according to a third embodiment of the present invention.

FIG. 7 is a sectional process view showing an application example of the semiconductor device manufacturing method according to the third embodiment of the present invention.

FIG. 8 is a sectional process view showing a method for manufacturing a semiconductor device according to a fourth embodiment of the present invention.

FIG. 9 is an experimental result showing a state of a shape change of a substrate due to heat treatment when an opening diameter of a thin film is equal to an opening diameter of a groove.

FIG. 10 is a schematic diagram showing how the shape of a substrate changes with heat treatment when the opening diameter of a thin film is equal to the opening diameter of a groove.

FIG. 11 is an experimental result showing a state of a shape change of a substrate due to a heat treatment when an opening diameter of a thin film is larger than an opening diameter of a groove.

FIG. 12 is a schematic view showing a state of a shape change of a substrate accompanying heat treatment when an opening diameter of a thin film is larger than an opening diameter of a groove.

FIG. 13 is a diagram showing the relationship between the opening diameter of the thin film and the time until the opening of the groove is closed.

[Explanation of symbols]

10, 30, 40, 50, 60, 80 Resist film 11, 22, 31, 32, 41, 62, 70, 90 Thin film 12, 20, 33, 42, 51, 61, 71, 82, 9
1 Substrate 13, 21, 34, 52, 64, 73, 83 Cavity 43 Sidewall material 63, 72 Second material 81 SiGe film 100, 103, 105 Thin film 101, 104, 106 Substrate 102, 107 Cavity

Claims (10)

[Claims] 1. A semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, the method comprising: depositing a thin film on the semiconductor substrate; removing a part of the thin film; Exposing the thin film to form an opening in the thin film, removing a portion of the exposed semiconductor substrate, and forming a groove having an opening that is the same as or smaller than the opening in the semiconductor substrate. A method of manufacturing a semiconductor device, comprising: a groove forming step; and a heat treatment step of applying a heat treatment to the groove to close an opening of the groove. 2. The method according to claim 1, wherein a groove forming step is performed after depositing a second thin film on at least a side wall of the opening of the thin film. 3. The method according to claim 1, wherein an area of the opening of the thin film is not less than 1 and not more than 9 times that of the groove. 4. The method according to claim 1, wherein the thin film is a single-layer film or a laminated film. 5. A semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, wherein the semiconductor substrate has a bottom cross-sectional area equal to that of an opening.
A method of manufacturing a semiconductor device, comprising: a groove forming step of forming a groove having an inverted taper shape that is twice or more; and a heat treatment step of applying a heat treatment to the groove to close an opening of the groove. 6. A semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, wherein: a groove forming step of forming a groove in the semiconductor substrate; and depositing a thin film on at least a bottom portion of the groove or a lower sidewall of the groove. A method of depositing a thin film, and a step of heat-treating the groove to close an opening of the groove. 7. The semiconductor substrate is a silicon substrate,
7. The method according to claim 6, wherein the thin film is a silicon oxide film or a silicon nitride film. 8. A semiconductor device manufacturing method for manufacturing a semiconductor device having a cavity in a semiconductor substrate, wherein: a thin film deposition step of depositing a thin film having a melting point lower than the melting point of the semiconductor substrate on the semiconductor substrate; A method of manufacturing a semiconductor device, comprising: a step of forming a groove by removing a part of a semiconductor substrate to form a groove; and a heat treatment step of applying a heat treatment to the groove to close an opening of the groove. 9. The semiconductor substrate is a silicon substrate,
9. The method according to claim 8, wherein the thin film is a SiGe thin film. 10. The method according to claim 8, wherein the thickness of the thin film is at least 10% of the size of the opening diameter of the groove.