JPH0992621A - Method for selective growth of semiconductor thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and selectively grow a required film thickness by adding a proper amount of etching gas as well as a film-formation material gas. SOLUTION: Silane and germane as film-formation material gases are intermittently supplied to a substrate and at the same time hydrochloric acid gas as an etching gas is continuously supplied to obtain a film thickness which is equal to or more than a critical selective growth film when selectively growing Si-Ge thin film on silicon substrate which is subjected to patterning with an insulation film by the chemical vapor growth method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively growing a semiconductor thin film in a semiconductor device (device) manufacturing process, and more particularly to a growth method for selecting the semiconductor thin film to have a selective growth critical film thickness or more.

[0002]

2. Description of the Related Art Currently, a silicon (Si) -based hetero bipolar transistor (HBT) is being actively developed. In particular, silicon-germanium (Si-Ge) HB
T is expected to make great progress in the field of LSI. However, in order to put Si-Ge HBT into practical use, it is essential to develop a self-aligned structure with LSI in mind.

The self-aligned structure is such that silicon dioxide (SiO ₂ ) or trisilicon tetranitride (Si ₃ N) is formed on a Si substrate.
₄ ) patterning with an insulating material such as Si and selectively expose the Si substrate surface that corresponds to the opening of the pattern
-Ge film is formed by the process of growing. In such selective growth, the Si substrate surface and the insulating film surface such as a SiO ₂ film have different attachment coefficients of molecules of a film forming material gas such as silane (SiH ₄ ), so that the Si substrate surface is kept for a certain period of time. It utilizes the mechanism that only the film is formed on.

However, after the end of this fixed time, film formation is also started on the surface of the insulating film and selective growth cannot be performed. Within this fixed time, a film having a thickness determined by the supply amount of the film forming material gas such as SiH ₄ and the film forming substrate temperature is formed on the Si substrate. If the thickness of this film is taken as the critical selective growth film thickness, the self-aligned structure cannot be formed unless the selective growth film thickness necessary for forming the HBT is smaller than this critical selective growth film thickness.

Therefore, conventionally, a method of adding an etching gas such as hydrochloric acid (HCl) gas has been used in order to improve the selectivity. The reason why the selectivity is improved by adding the etching gas is considered to be that the etching gas suppresses the formation of nuclei (nuclei of Si and Ge) of the film forming material on the patterned insulating film.

[0006]

However, there is a drawback that the growth rate is remarkably reduced when the etching gas is added. Therefore, it is necessary to reduce the addition amount of the etching gas in order to increase the growth rate, and if the addition amount of the etching gas is reduced, the phenomenon that the selectivity deteriorates occurs. As a result, it becomes difficult to increase the thickness of the critical selective growth film, and it becomes impossible to perform the selective growth of a necessary film thickness, so that there is a problem that the self-aligned structure cannot be formed.

The present invention eliminates the above-mentioned problems and provides a selective growth method for a semiconductor thin film capable of accurately and selectively growing a required film thickness by adding an appropriate amount of etching gas together with a film forming material gas. With the goal.

[0008]

In order to achieve the above-mentioned object, the present invention provides (1) a chemical vapor deposition method for selectively growing a silicon substrate patterned with an insulating film to obtain a critical selective growth film thickness. In the method for selectively growing a semiconductor thin film having the above film thickness, the film forming material gas is intermittently supplied to the substrate and the halogen-based gas is continuously supplied.

Therefore, the supply of silane and germane gas as the film forming material gas is stopped before the nuclei of the film forming material grow large on the insulating film, and the sulfuric acid gas as the etching gas continues to flow, and the effect of the etching is obtained. Thus, the nuclei of the film forming material formed on the insulating film are removed. As a result, the state returns to the initial state in which nuclei of the film forming material are not formed on the insulating film. Then, after this step, if silane and germane gas are continuously supplied to start film formation, Si is formed in the opening of the patterned insulating film.
-Deposition of the Ge thin film starts, but since nucleation of the film forming material starts on the insulating film again, continuous selective growth becomes possible.

By repeating the above steps, even if it is desired to grow a Si-Ge thin film thicker than the critical selective growth film thickness, it is possible to carry out accurate selective growth. (2) In a selective growth method of a semiconductor thin film having a film thickness equal to or larger than a critical selective growth film thickness, a film forming material gas is continuously grown by selectively growing the silicon substrate patterned by an insulating film by a chemical vapor deposition method. The halogen-based gas is supplied to the substrate while being intermittently increased and decreased.

Therefore, by increasing the flow rate of the hydrochloric acid gas as an etching gas in a pulsed manner before the nuclei of the film forming material grow large on the insulating film, it is formed on the insulating film by the effect of the etching gas. A step of removing the nuclei of the film forming material is performed. By this step, the initial state in which nucleation of the film forming material is not formed on the insulating film is restored. Then, after this step, the flow rate of the hydrochloric acid gas is returned to the flow rate before being increased, and the flow rate is supplied together with silane and germane gas to start the film formation, thereby depositing the Si—Ge thin film in the openings of the patterned insulating film. However, since nucleation of the film forming material starts on the insulating film again, continuous selective growth becomes possible.

As described above, according to this embodiment, since the film forming material gas is not temporarily stopped and the semiconductor thin film is selectively grown, the film forming material gas can be easily supplied. In addition, the Si-Ge film can be deposited on the Si substrate with almost no change in the film formation rate. By repeating the above steps, accurate selective growth can be performed even when it is desired to grow a Si—Ge thin film thicker than the critical selective growth film thickness.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. It should be noted that this drawing merely schematically shows the dimensions, shapes and positions of the respective constituents to the extent that the present invention can be understood. Further, although specific materials are used in the following description, these materials and conditions are merely preferred examples, and thus the present invention is not limited thereto.

FIG. 1 is a diagram schematically showing the overall structure of an apparatus for carrying out the present invention. As shown in FIG. 1, this apparatus is provided with a metal reaction furnace (chamber) 11 and is configured such that the chamber wall does not reach a high temperature during thin film formation due to, for example, water cooling. Also, the reactor 1
The substrate 15 is installed downward on the substrate support 13 in 1 and the substrate 15 can be placed freely in and out.

A substrate heating mechanism 12 is provided in the reaction furnace 11, and is constructed so that it can be heated by any suitable mechanism, for example, resistor heating. In the vicinity of the substrate 15, temperature measuring means 14 for measuring the surface temperature of the substrate 15, for example, a thermocouple is provided so that the temperature of the substrate heating mechanism 12 can be controlled. The reaction furnace 11 has a structure in which an upper part (substrate heating mechanism 12 side) and a lower part (gas head 16 side) are separated by a substrate support 13. In addition, each part has an independent exhaust port 1
7 and 18 are provided. Any suitable exhaust means 20, 21 and 22 for evacuating the reaction furnace 11 are exhausted through the automatic opening / closing valves 24 and 25 to the exhaust ports 17 and 1.
It is possible to control the pressure inside the reaction furnace 11 to any appropriate pressure independently for each of the upper part and the lower part by connecting and disconnecting the valves 24 and 25 to appropriate values, and to form an ultrahigh vacuum exhaust state. The degree of vacuum in the reaction furnace 11 is measured by the vacuum gauges 30 and 31, and the vacuum gauges 30 and 31 are used.
For this, a suitable vacuum gauge is selected according to the required degree of vacuum.

The reaction furnace 11 is provided with a gas head 16 corresponding to the substrate 15. The gas head 16 is provided with gas introduction passages 35 a and 35 b and a cooling water introduction passage 36 penetrating the outer wall of the reaction furnace 11. Automatic opening / closing valves 50, 51, 5 are provided in the gas introduction paths 35a and 35b.
Connected through the necessary valves such as 2 and 53,
A necessary gas can be introduced into the reaction furnace 11 via the gas head 16. Also, these valves 5
0, 51, 52, 53 and reaction gas supply units 70, 71, 7
The automatic flow rate controllers 60, 61, 62 and 63 are provided between the two and the carrier gas supply unit 73.

Further, automatic opening / closing valves 80, 81 and 82 are connected to the reaction gas supply units 70, 71 and 72, respectively, and the automatic opening / closing valves 50, 51, 52 and 80,
By opening and closing 81 and 82 respectively suitably,
Exhaust means 23 can be independently exhausted without passing through the reaction furnace 11. And valves 50, 51, 5
By opening and closing 2 and 53 respectively arbitrarily,
A desired gas can be supplied to the reaction furnace 11 while setting an arbitrary gas mixing ratio.

Hereinafter, a method of selectively growing a Si-Ge thin film showing an embodiment of the present invention will be described. FIG. 2 is a diagram for explaining a substrate temperature profile and a gas supply cycle according to the first embodiment of the present invention. FIG. 2A shows a substrate temperature profile, where the horizontal axis represents time and the vertical axis represents time. The substrate temperature is shown. FIG. 2B shows a profile of a flow rate of silane as a film forming material gas, FIG. 2C shows a profile of a flow rate of Germane as a film forming material gas, and FIG. 2D shows a flow rate of hydrochloric acid gas as an etching gas. The respective profiles are shown, with the horizontal axis representing time and the vertical axis representing various gas flow rates.

The specific substrate temperature, flow rate and supply time of various gas flow rates in FIG. 2 are merely examples, and the present invention is not limited to these. The substrate 15 is mainly made of Si
A substrate is used. Cleaning of the Si substrate 15 and removal of the oxide film are performed by solution treatment outside the reaction furnace. First, the Si substrate 15 is immersed in a sulfuric acid-hydrogen peroxide solution heated to 120 ° C. for about 10 minutes to form an oxide film of about 10 Å. After that, 1% HF
Immerse in the solution for about 30 seconds to completely remove the oxide film. Immediately thereafter, the Si substrate 15 is introduced into the reaction furnace.

Next, the selective growth step of the Si-Ge thin film will be described. (1) First, after introducing the Si substrate 15 into the reaction furnace 11, the automatic opening / closing valves 24 and 25 are opened, and the exhaust means 2
0, 21 and 22 are used, and the inside of the reaction furnace 11 is, for example, 1 × 1.
^{Evacuate to} an ultrahigh vacuum of 0 ^-8 Pa and clean. Then Si
While measuring the temperature of the substrate 15 by the temperature measuring means 14, a radiant heating by the substrate heating mechanism 12 in the reaction furnace 11 sets a predetermined temperature, for example, a suitable temperature between 900 and 1200 ° C.,
For example, the Si substrate 15 is held at 1000 ° C. for about 10 minutes. By this process, the surface of the Si substrate 15 is cleaned. Then, the temperature of the Si substrate 15 is set to a suitable film forming temperature between 600 and 900 ° C., for example, 650 ° C.

Next, from the Si-containing group IV hydrogen dilution gas supply part 70, for example, hydrogen diluted 10% silane (Si
H ₄ ) Open the automatic opening / closing valve 80 for gas, and exhaust the gas 23
Shed on. In this state, the automatic opening / closing valve 81 is opened, and the group IV gas supply part 71 containing germanium in addition to silane is added.
Then, for example, hydrogen-diluted 1% germane (GeH ₄ ) gas is flown to the exhaust means 23. At this time, the flow rates of silane and germane are adjusted in advance by the automatic flow controllers 60 and 61 so that the mixture ratio of silane gas and germane gas becomes a desired ratio. For example, silane gas is 30 ccm,
Set Germanicus to 2.5 ccm. Further, the automatic opening / closing valve 82 is opened, and from the etching gas supply unit 72,
For example, hydrochloric acid (HCl) gas is flown through the exhaust means 23. At this time, the flow rate of the hydrochloric acid gas is preset by the automatic flow controller 62 so that the flow rate of the hydrochloric acid gas becomes a desired value. For example, the flow rate of hydrochloric acid gas is set to 10 ccm. Thereafter, the automatic opening / closing valves 80, 81 and 82 are closed, and the silane gas, germane gas and hydrochloric acid gas are supplied to the reaction furnace 11 by the automatic opening / closing valves 50, 51 and 52. At this time, selective growth of the Si-Ge thin film is started.

Further, thereafter, a Si-Ge thin film is formed according to the gas supply cycle as shown in FIG. During the gas supply cycle, when the silane and germane gas are not supplied into the reaction furnace 11, the automatic opening / closing valves 50 and 51 are closed, the automatic opening / closing valves 80 and 81 are opened, and the gas is discharged to the exhaust means 23. It is flowing. This makes it possible to minimize fluctuations in gas flow rate when supplying silane and germane gas into the reaction furnace 11.

In the gas supply cycle, the supply time of the silane and germane gas is such that the critical selective growth film thickness is not exceeded. Further, the time during which the silane and germane gas are not supplied into the reaction furnace 11, that is, the time during which only hydrochloric acid gas is supplied is set to a time for removing the nuclei of the film forming material being formed on the patterned insulating film. . Si
-Automatic opening / closing valve 50 immediately after the growth of Ge thin film,
51 and 52 are closed so that silane gas, germane gas and hydrochloric acid gas are not supplied into the reaction furnace 11, and the substrate 15 is cooled while flowing hydrogen gas at a suitable ratio. Finally, the substrate 15 is taken out of the reaction furnace 11.

By the way, the film forming material gas, that is, silane and germane gas is supplied for S only in the opening of the patterned insulating film, that is, on the Si substrate 15.
The i-Ge thin film is deposited, and the selective growth state in which the nucleation of the film forming material is suppressed as much as possible is brought about by the influence of the etching gas, that is, the hydrochloric acid gas, on the insulating film. This state is maintained until the critical selective growth film thickness is reached. However, if the film deposition is continued as it is, that is, the silane and germane gas are continuously supplied, the nucleation of the film forming material cannot be sufficiently suppressed even if the hydrochloric acid gas is supplied, and the nuclei of the film forming material continue to grow. The formation of the Si-Ge thin film also begins on the insulating film. That is, the selective growth cannot be performed.

Therefore, in this embodiment, as shown in FIG. 2, etching is performed by temporarily stopping the supply of silane and germane gas before the nuclei of the film-forming material grow large and continuing to flow hydrochloric acid gas as an etching gas. Depending on the effect,
A step of removing nuclei of the film forming material formed on the insulating film was performed. Through this step, the insulating film is returned to the initial state where the film forming material is not nucleated. Then, after this step, if silane and germane gas are continuously supplied to start film formation, Si-- is formed in the opening of the patterned insulating film.
Deposition of the Ge thin film starts, but nucleation of the film forming material starts again on the insulating film, which enables selective growth.

By repeating the above steps, selective growth can be performed even when it is desired to grow a Si-Ge thin film thicker than the critical selective growth film thickness. Hereinafter, in order to facilitate the understanding of the selective growth step of the Si-Ge thin film of the present invention, description will be given using schematic diagrams. Figure 3 shows the Si
It is a schematic cross section of the selective growth process of a-Ge thin film.

(1) First, as shown in FIG. 3A, the insulating film 101 is patterned on the silicon substrate 15 to set the substrate. (2) Next, as shown in FIG. 3B, by supplying silane and germane gas as a film forming material gas, Si-G is formed on the exposed surface of the silicon substrate 15 as described above.
e The thin film 102 is selectively grown (critically selected growth film thickness). At that time, in the final stage, by supplying silane and germane gas as film forming material gas (t ₁ , for example, 15 minutes supply),
Gradually, nuclei of film forming materials (Si and Ge) on the insulating film 101
03 is growing.

(3) Further, when the supply of silane and germane gas as the film forming material gas continues, as shown in FIG. 3C, the nucleus 103 of the film forming material grows on the insulating film 101,
The Si-Ge thin film 102 cannot be selectively grown. (4) Therefore, in this embodiment, as shown in FIG. 3D, the supply of silane and germane gas as the film forming material gas is stopped (t ₂ , for example, stopped for 3 minutes), and the etching gas is used. Insulating film 1 by supplying only hydrochloric acid gas as
By etching the nucleus 103 of the film forming material on 01, the surface of the insulating film 101 is returned to the initial state.

(5) Next, as shown in FIG. 3E, when silane and germane gas as film forming material gases are supplied again (t ₁ , for example, 15 minutes), the surface of the insulating film 101 is initially formed. Since it has returned to the state of Si-Ge thin film 10
The selective growth of No. 2 can be continued, and the selective growth of the film thickness equal to or more than the critical selective growth film thickness can be performed. By the way,
A film forming material gas is supplied for up to 69 minutes, and a hydrochloric acid gas as an etching gas is supplied for 72 minutes.

Next, a Si-G showing a second embodiment of the present invention.
A method for selectively growing a thin film will be described. FIG. 4 is a diagram for explaining a substrate temperature profile and a gas supply cycle according to the second embodiment of the present invention. In the substrate temperature profile, the horizontal axis represents time, the vertical axis represents the substrate temperature, and the gas supply cycle represents the horizontal axis. Times and various gas flow rates are plotted on the vertical axis.

The specific substrate temperature, flow rate and supply time of various gas flow rates in FIG. 4 are merely examples, and the present invention is not limited to these. Similar to the first embodiment,
As the substrate 15, a Si substrate is mainly used. Cleaning of the Si substrate 15 and removal of the oxide film are performed by solution treatment outside the reaction furnace. First,
The Si substrate 15 is dipped in an aqueous solution of sulfuric acid-hydrogen peroxide heated to 120 ° C. for about 10 minutes to form an oxide film of about 10 Å. Then, it is immersed in a 1% HF solution for about 30 seconds to completely remove the oxide film. Immediately thereafter, the Si substrate 15 is introduced into the reaction furnace.

Next, the selective growth process of the Si-Ge thin film will be described. After introducing the Si substrate 15 into the reaction furnace 11, the automatic opening / closing valves 24 and 25 are opened, and the exhaust means 2
0, 21 and 22 are used, and the inside of the reaction furnace 11 is, for example, 1 × 1.
^{Evacuate to} an ultrahigh vacuum of 0 ^-8 Pa and clean. Then Si
While measuring the temperature of the substrate 15 by the temperature measuring means 14, a radiant heating by the substrate heating mechanism 12 in the reaction furnace 11 sets a predetermined temperature, for example, a suitable temperature between 900 and 1200 ° C.,
For example, the Si substrate 15 is held at 1000 ° C. for about 10 minutes. By this process, the surface of the Si substrate 15 is cleaned. Then, the temperature of the Si substrate 15 is set to a suitable film forming temperature between 600 and 900 ° C., for example, 650 ° C.

Next, for example, hydrogen diluted 10% silane (SiH ₄ ) is supplied from the group IV hydrogen diluted gas supply portion 70 containing Si.
The gas is flown to the exhaust means 23 by opening the automatic opening / closing valve 80.
In this state, the automatic opening / closing valve 81 is opened, and hydrogen-diluted 1% germane (GeH ₄ ) gas, for example, is supplied to the exhaust means 23 from the group IV system gas supply part 71 containing germanium in addition to silane.

At this time, the flow rates of silane and germane are adjusted in advance by the automatic flow controllers 60 and 61 so that the mixture ratio of silane gas and germane gas becomes a desired ratio. For example, silane gas is set to 30 ccm and germane gas is set to 2.5 ccm. Further, the automatic opening / closing valve 82 is opened, and, for example, hydrochloric acid (HCl) gas is caused to flow from the etching gas supply unit 72 to the exhaust means 23.

At this time, the flow rate of the hydrochloric acid gas is preset by the automatic flow controller 62 so that the flow rate of the hydrochloric acid gas becomes a desired value. For example, the flow rate of hydrochloric acid gas is 10
Set to ccm. It is set to 15 ccm when the flow rate is increased. Thereafter, the automatic opening / closing valves 80, 81 and 82 are closed, and the silane gas, germane gas and hydrochloric acid gas are supplied to the reaction furnace 11 by the automatic opening / closing valves 50, 51 and 52. At this time, selective growth of the Si-Ge thin film is started.

As described above, as the film forming material gas, for example, silane gas is 30 ccm and germane gas is 2.5 c
cm, respectively, for 60 minutes, and hydrochloric acid gas as an etching gas is supplied at a lower limit of 10 ccm for 12 minutes and an upper limit of 15 cm.
The process is repeated 4 times for 3 minutes at ccm, that is, the processing is performed by increasing or decreasing the flow rate of hydrochloric acid gas as an etching gas.

In this way, in the gas supply cycle, as an example, the time until the flow rate of the hydrochloric acid gas shown in the figure increases in a pulsed manner is set to the time during which the critical selective growth thin film is not exceeded.
The time during which the flow rate of the hydrochloric acid gas is increased in a pulsed manner is such that the nucleus of the film-forming material that is being formed on the patterned insulating film can be removed. S
Immediately after the growth of the i-Ge thin film, the automatic opening / closing valve 5
By closing 0, 51 and 52, the silane gas, germane gas and hydrochloric acid gas are not supplied into the reaction furnace 11, and the substrate is cooled while flowing hydrogen gas at a suitable ratio. Finally, the substrate 15 is taken out of the reaction furnace 11.

By the way, as shown in FIG. 3, the time until the flow rate of the hydrochloric acid gas as the etching gas increases in a pulsed manner is the opening of the patterned insulating film, that is, S.
The Si—Ge thin film is deposited only on the i substrate 15, and the selective growth state in which the nucleation of the film forming material is suppressed as much as possible due to the influence of the etching gas, that is, the hydrochloric acid gas, is formed on the insulating film. This state is maintained until the critical selective growth film thickness is reached. However, if the film deposition is continued as it is, that is, if silane and germane gas are continuously supplied, nucleation of the film-forming material cannot be sufficiently suppressed even if hydrochloric acid gas is supplied,
The nuclei of the film-forming material continue to grow and the Si-Ge thin film starts to be formed on the insulating film, so that selective growth cannot be performed.

Therefore, according to this embodiment, the flow rate of the hydrochloric acid gas is changed before the nuclei of the film forming material grow large on the insulating film.
As shown in FIG. 3, by increasing the number of pulses,
A step of removing the nucleus of the film forming material formed on the insulating film by the effect of the etching gas is performed. Through this step, the insulating film is returned to the initial state where the film forming material is not nucleated.

After this step, the flow rate of the hydrochloric acid gas is returned to that before the increase, and the returned flow rate of the hydrochloric acid gas is supplied together with the silane and germane gas to start film formation. Si in the opening
-Deposition of a Ge thin film starts, but nucleation of a film forming material starts again on the insulating film, so that selective growth is possible. Further, the state on the insulating film immediately before increasing the flow rate of hydrochloric acid gas in a pulsed state is a state in which nucleation of the film forming material starts,
It is considered that the nuclei of the sparse film forming material of several atomic layers at most are deposited on the insulating film. Therefore, it is possible to remove the nuclei of the film forming material on the insulating film only by increasing the flow rate of the etching gas without temporarily stopping the film forming material gas and increasing the effect of etching.

As a result, the Si—Ge film can be deposited on the patterned opening of the insulating film, that is, on the Si substrate with almost no change in the film forming rate. By repeating the above steps, selective growth can be performed even when it is desired to grow a Si—Ge thin film thicker than the critical selective growth film thickness. Further, the present invention has the following utilization modes.

The group IV hydrogen diluting gas containing silicon in the above-mentioned first and second embodiments is not limited to the silane gas, and for example, silane (SiH ₄ ), disilane (Si ₂ H ₆ ), Methylsilane [Si (CH ₃ )
H ₃ ], trisilane (Si ₃ H ₈ ), dimethylsilane [Si (CH ₃ ) ₂ H ₂ ], trimethylsilane [Si
(CH ₃ ) ₃ H], tetramethylsilane [Si (C
H _{3) 4],} hexamethyl disilane [Si ₂ (CH _3)
6 ] and fluorotrimethylsilane [Si (CH ₃ ) ₃
F], fluorodimethylsilane [Si (CH ₃ )
₂ F ₂ ] may be used alone or in combination of two or more.

In the above-mentioned embodiments, the group IV gas containing germanium is not limited to germane gas. For example, germane (GeH ₄ ), germanium tetrafluoride (GeF ₄ ), germanium difluoride. (Ge
F ₂ ), germanium fluoride (GeF) and fluorogermane (GeH ₃ F) gas groups may be used alone or in combination of two or more.

Further, in the above-mentioned embodiments, the etching gas is not limited to the hydrochloric acid gas, for example, hydrochloric acid (HCl), chlorine (Cl ₂ ), fluorine (F ₂ ), bromine (Br ₂ ), etc. 1 out of the working gas group
You may use it in combination with 2 or more types. In addition,
The present invention is not limited to the above embodiments, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0045]

As described in detail above, according to the present invention, the following effects can be achieved. (1) According to the invention of claim 1, the supply of silane and germane gas as a film forming material gas is performed before the nucleus of the film forming material grows large on the insulating film of the Si substrate patterned with the insulating film. After stopping, the sulfuric acid gas as an etching gas was allowed to continue to flow to remove the nuclei of the film forming material formed on the insulating film due to the effect of etching.

By this step, the initial state where nuclei of the film forming material are not formed on the insulating film is restored. Then, if silane and germane gas are continuously supplied after this step to start film formation, deposition of the Si—Ge thin film starts in the opening of the patterned insulating film, but the film forming material is newly formed on the insulating film. Since the nucleation of P. cerevisiae begins, continuous selective growth becomes possible.

By repeating the above steps, even if it is desired to grow a Si-Ge thin film thicker than the critical selective growth film thickness, it is possible to carry out an accurate selective growth. (2) According to the second aspect of the invention, the flow rate of hydrochloric acid gas as an etching gas is changed in a pulsed manner before the nuclei of the film-forming material grow large on the insulating film of the Si substrate patterned with the insulating film. By increasing the number, a step of removing the nuclei of the film forming material formed on the insulating film by the effect of the etching gas is performed.

By this step, the initial state where the film forming material is not nucleated on the insulating film is returned to the initial state. Then, after this step, the flow rate of hydrochloric acid gas is returned to the flow rate before being increased, and when the film formation is started by supplying the gas together with silane and germane gas, Si is formed in the opening of the patterned insulating film.
-Deposition of the Ge thin film starts, but nucleation of the film forming material starts again on the insulating film, so that continuous selective growth is possible.

As described above, according to this embodiment, since the film forming material gas is not temporarily stopped, it is easy to supply the film forming material gas, and almost all the film is formed on the Si substrate. It is possible to deposit a Si-Ge film without changing the speed. By repeating the above steps, accurate selective growth can be performed even when it is desired to grow a Si—Ge thin film thicker than the critical selective growth film thickness.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an overall configuration of an apparatus for carrying out the present invention.

FIG. 2 is a diagram illustrating a substrate temperature profile and a gas supply cycle according to the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of the selective growth step of the Si—Ge thin film showing the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a substrate temperature profile and a gas supply cycle showing a second embodiment of the present invention.

[Explanation of symbols]

11 Metal Reaction Furnace (Chamber) 12 Substrate Heating Mechanism 13 Substrate Support 14 Temperature Measuring Means 15 Substrate 16 Gas Head 17,18 Exhaust Ports 20, 21, 22, 23 Exhaust Means 24, 25, 50, 51, 52, 53 , 80, 81, 8
2 Automatic opening / closing valve 30, 31 Vacuum gauge 35a, 35b Gas introduction path 36 Cooling water introduction path 60, 61, 62, 63 Automatic flow rate controller 70, 71, 72 Reactant gas supply part 73 Carrier gas supply part 101 Insulating film 102 Si- Ge thin film 103 Core of film forming material (Si and Ge)

Claims (2)

[Claims] 1. A method of selectively growing a semiconductor thin film having a film thickness equal to or larger than a critical selective growth film thickness by selectively growing a silicon substrate patterned with an insulating film by a chemical vapor deposition method, and intermittently supplying a film forming material gas. Method for selectively growing a semiconductor thin film, characterized in that the halogen-based gas is continuously supplied while being supplied to the substrate. 2. A chemical vapor deposition method is used to selectively grow a silicon substrate patterned with an insulating film, and a deposition material gas is continuously supplied in the selective growth method of a semiconductor thin film having a film thickness equal to or more than a critical selective growth film thickness. And a halogen-based gas are intermittently increased and decreased and then supplied to the substrate.