JPH07288236A - Apparatus and method for low-pressure vapor growth - Google Patents

Abstract

PURPOSE:To grow a vapor-growth film having the excellent film quality by eliminating the abnormal growth at the surface of a sample at the time of low-pressure vapor growth. CONSTITUTION:In a low-pressure vapor growth apparatus 1, an inner process tube 11 having an inner space 21 for causing the vapor growth is provided. An outer process tube 12 is provided outside the inner process tube 11 through a communicating space 31 from the side of one end 11A to an outer space 21. A nozzle 41, which supplies raw material gas 81 into the inner space 21, is provided in the communicating space 31. A heater 51 is provided outside the outer process tube 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure vapor phase growth apparatus and a low pressure vapor phase growth method.

[0002]

2. Description of the Related Art Among low pressure vapor phase growth apparatuses (hereinafter referred to as LPCVD apparatuses), particularly batch type LPCVD apparatuses are
It is widely used as a CVD apparatus for forming a thin film of silicon, silicon nitride, silicon oxide or the like. Since this type of apparatus processes about 100 wafers at a time, the scale of the apparatus becomes large. Therefore, the volume of the process chamber of the apparatus becomes large. Therefore, there is a problem that many atmospheric components harmful to the semiconductor device remain inside the process chamber.

Especially when a silicon nitride film is formed,
There is a problem that oxygen atoms are mixed in the silicon nitride film to lower the dielectric constant.

Therefore, conventionally, a load lock chamber or a chamber having a nitrogen atmosphere is provided in front of the process chamber to prevent the entrainment of atmospheric components into the process chamber.

Here, the conventional vertical LPCVD apparatus is
A brief description will be given with reference to the schematic configuration sectional view of FIG.

As shown in the figure, an inner process tube 111 having an internal space 121 for producing a deposited film (not shown) on the surface of a plurality of samples 191 by vapor phase growth is installed. An outer process tube 112 is installed outside the inner process tube 111 via a space 131.

A nozzle 141 for supplying a raw material gas is provided at one end of the inner process tube 111, and an exhaust pipe 14 connected to an exhaust device (not shown) is provided at the other end.
2 is connected. Further outer process tube 11
A heater 151 is provided outside the unit 2.

A load lock chamber 171 is provided below the inner process tube 111, and a boat 161 for loading and unloading the sample 191 is provided between the load lock chamber 171 and the internal space 121. This boat 161
Is driven in the arrow direction by a drive device (not shown). The LPCVD apparatus 101 is configured as described above.

In the LPCVD apparatus 101, the nozzle 1
The raw material gas 181 from 41 is the inner process tube 1
The gas is exhausted from the exhaust pipe 142 through the internal space 121 of 11. Therefore, the source gas 181 supplied from the nozzle 141 reaches the sample 191 at a small distance, and
A vapor growth reaction occurs on the surface of 91.

[0010]

[Problems to be Solved by the Invention] LPCVD having the above structure
When the apparatus is provided with a load lock chamber (or a chamber of nitrogen atmosphere) for preventing the air from being entrained in the inner process tube, the silicon nitride film causes abnormal growth.

When the conventional apparatus was used to carry the sample in the atmosphere, abnormal atmosphere was suppressed by the atmosphere taken into the process tube. However, with a load lock chamber or a chamber with a nitrogen atmosphere, the atmosphere does not mix into the process tube at all, so the factors causing abnormal growth cannot be excluded. Therefore, abnormal growth occurred.

This abnormal growth is especially caused by silicon nitride (Si
N) It occurs early in forming a film. That is, this is a phenomenon in which a speckled silicon nitride (SiN) film having a silicon (Si) content higher than stoichiometry is formed on a silicon substrate. On a wafer having a diameter of 200 mm, about 10,000 spotted silicon nitride films are formed. This is because the chemical vapor deposition of silicon nitride is sensitive to the state of the surface of the silicon substrate. For example, since an unstable natural oxide film grows on a silicon substrate, a silicon nitride film preferentially grows from the unstable portion to form a hemispherical film (Journal of Applied Physics, 61 [11]). (199
2) p. 1147). This is extremely harmful to the semiconductor device.

An object of the present invention is to provide a low pressure vapor phase growth apparatus and a low pressure vapor phase growth method in which abnormal growth does not occur during vapor phase growth.

[0014]

The present invention is a low-pressure vapor phase growth apparatus and a low-pressure vapor phase growth method that have been made to achieve the above object. That is, the low pressure vapor phase growth apparatus is provided with an inner process tube having an internal space for forming a deposited film on the sample surface by vapor phase growth. An outer process tube is installed on the outer side of the inner process tube via a space between the tubes which communicates with the inner space from one end side of the inner process tube. Further, a nozzle for supplying the raw material gas to the internal space is provided in the space between the tubes. Further, a heater is provided outside the outer process tube.

Further, the outlet of the nozzle is arranged in the space between the tubes from the other end side of the inner process tube.

As a low-pressure vapor phase growth method, a heater is used to heat the inner space of the inner process tube and the space between the tubes to a film forming temperature. In that state, the raw material gas is supplied from the nozzle to the internal space through the space between the tubes. Then, a vapor phase growth reaction is caused on the sample surface.

[0017]

In the low-pressure vapor phase growth apparatus having the above structure, since the heater is installed outside the outer process tube, the internal space and the space between the tubes are heated. In addition, since the nozzle that supplies the raw material gas is installed in the space between the tubes,
The raw material gas supplied from the nozzle enters the inner space of the inner process tube through the space between the tubes. In this way, by sufficiently keeping the distance from the nozzle outlet to the wafer, the raw material gas is sufficiently heated by the heater and becomes in an activated state. The wafer is also sufficiently heated by the heater.

Further, since the outlet of the nozzle is arranged in the space between the tubes from the other end side of the inner process tube, the raw material gas discharged from the nozzle is heated for a long time in the space between the tubes. Therefore, the raw material gas becomes almost active when it enters the inner space of the inner process tube.

In the low pressure vapor phase growth method, a heater is used to
While the inner space of the inner process tube and the space between the tubes are heated to the film formation temperature, the raw material gas is supplied from the nozzle, so that the raw material gas is heated to be in an active state and the inside of the inner process tube is heated. Supplied to space.
Therefore, the vapor phase growth reaction occurs on the surface of the sample in the state where the reactivity of the source gas is high, so that abnormal growth does not occur.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the schematic sectional view of FIG.

As shown in the figure, the low pressure vapor phase growth apparatus 1 is provided with an inner process tube 11 having an internal space 21 for causing a vapor phase growth reaction. The inner space 21 from the end 11A side of the inner process tube 11
The outer process tube 12 is installed outside the inner process tube 11 through a space 31 between the tubes communicating with the inner process tube 11.

A nozzle 41 for supplying a source gas 81 is provided in the space 31 between the tubes. The outlet 41A of the nozzle 41 is disposed in the space 31 between the inner process tube 11 and the other end 11B thereof. An exhaust pipe 42 connected to an exhaust device (not shown) is connected to the other end 11B side of the inner process tube 11.

A heater 51 is provided outside the outer process tube 12. The heater 51 is composed of, for example, a resistance heating element.

A load lock chamber 71 connected to the other end 11B is provided below the inner process tube 11. A boat 61 for loading and unloading a plurality of samples 91 is provided in the load lock chamber 71 between the load lock chamber 71 and the internal space 21 of the inner process tube 11. The boat 161 is driven in the arrow A direction by a drive device (not shown).

The low pressure vapor phase growth apparatus 1 is constructed as described above.

In the low pressure vapor phase growth apparatus 1 having the above structure, since the heater 51 is installed outside the outer process tube 12, the space 31 of the tube tube provided between the inner process tube 11 and the outer process tube 12 is provided. Is heated. A space 41 between the tubes is provided so as to communicate with the internal space 21 from one end 11A side of the inner process tube 11, and a nozzle 41 that supplies the source gas 81 to the space 31 between the tubes on the other end 11B side of the inner process tube 11 is provided. As a result, the raw material gas 81 supplied from the nozzle 41 enters the internal space 21 of the inner process tube 11 through the space 31 between the tubes. In this way, by keeping a sufficient distance from the outlet of the nozzle 41 to the sample 91, the source gas 81 is sufficiently heated by the heater 51 and becomes in an active state. The sample 91 is also sufficiently heated by the heater 51.

Since the outlet 41A of the nozzle 41 is arranged in the space 31 between the tubes from the other end 11B side of the inner process tube 11, the source gas 81 discharged from the nozzle 41 is in the space 31 between the tubes. Is sufficiently heated to reach the film formation temperature. Therefore, before entering the inner process tube 11, it is in an active state.

Next, a vapor phase growth method using the low pressure vapor phase growth apparatus 1 will be described with reference to the film forming process diagram of FIG. In the figure, as an example, a silicon substrate is used as the sample 91 and a silicon nitride film is deposited on the surface thereof.

As shown in (1) of FIG. 2, the heater 51 heats the internal space 21 of the inner process tube 11 and the space 31 between the tubes to a film forming temperature (for example, 760 ° C.). Then, the raw material gas 81 is supplied from the nozzle 41 to the space 31 between the tubes. As the raw material gas 81, for example, a mixed gas of ammonia (NH ₃ ) having a flow rate of 600 sccm, dichlorosilane (SiH ₂ Cl ₂ ) having a flow rate of 90 sccm, and nitrogen having a flow rate of 1000 sccm is used. The source gas 81 is heated in the space 31 between the tubes to a temperature substantially equal to the film forming temperature and enters the internal space 21.

Then, as shown in FIG. 2 (2), the boat 61 is raised to accommodate a plurality of samples (for example, wafers) 91 in the internal space 21 of the inner process tube 11. At that time, the source gas 81 is transported from the space 31 between the tubes to the internal space 21, and the pressure therein is, for example, 50 Pa.
Adjusted to. Then, a vapor phase growth reaction occurs on the surface of the sample 91, and a thin film of silicon nitride (not shown) is formed on the surface of the sample 91.

In the low pressure vapor phase growth method, the heater 41 supplies the source gas 81 from the nozzle 41 while the internal space 21 of the inner process tube 11 and the space 31 between the tubes are heated to the film forming temperature. From raw material gas 8
1 is activated and supplied to the internal space 21 of the inner process tube 11. For this reason, the raw material gas 81 having low reactivity is mostly present on the outlet side of the nozzle 41 in the space 31 between the tubes, and hardly present on the inlet side of the inner process tube 11. Therefore, with the reactivity of the source gas 81 increased, the inner process tube 11
Since the source gas 81 enters the internal space of the film, the film formation proceeds without causing abnormal growth in the vapor growth reaction on the surface of the sample 91.

[0032]

As described above, according to the low pressure vapor phase growth apparatus of the present invention, the heater is installed outside the outer process tube, and the inner process tube is provided between the inner process tube and the outer process tube. Since the space between the tubes communicating from one end side of the tube to the inside is provided and the nozzle for supplying the raw material gas is provided in the space between the tubes, the raw material gas supplied from the nozzle is heated in the space between the tubes and the inner process is performed. Enter the inner space of the tube. Therefore, a sufficient distance can be secured from the outlet of the nozzle to the sample, and the raw material gas is sufficiently heated to be in an activated state. Therefore, it is possible to form a film on the sample surface without causing abnormal growth, so that the quality of the formed film can be improved.

Further, according to the low pressure vapor phase growth apparatus in which the outlet of the nozzle is arranged in the space between the tubes from the other end side of the inner process tube, a sufficient distance can be secured from the nozzle outlet to the inlet of the inner process tube. Therefore, the raw material gas can be sufficiently heated in the meantime to bring it into an active state.

According to the low-pressure vapor phase growth method of the present invention, the raw material gas is supplied from the nozzle while the inner space of the inner process tube and the space between the tubes are heated to the film forming temperature by the heater. The raw material gas can be activated in the space between the tubes and supplied to the inner space of the inner process tube. Therefore, the vapor phase growth reaction can occur on the surface of the sample in the state where the reactivity of the source gas is high, so that the film formation can be advanced without causing abnormal growth.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a vapor phase growth method.

FIG. 3 is a schematic configuration sectional view of a conventional example.

[Explanation of symbols]

 1 Low Pressure Vapor Deposition Device 11 Inner Process Tube 11A (Inner Process Tube) One End 11B (Inner Process Tube) Other End 12 Outer Process Tube 21 Internal Space 31 Tube Space 41 Nozzle 41A Outlet 51 Heater 81 Raw material gas 91 Sample

Claims (3)

[Claims] 1. An inner process tube having an inner space for forming a deposited film on a sample surface by vapor phase growth, and a tube outside the inner process tube, the tube leading from the one end side of the inner process tube to the inner space. A low-pressure vapor phase growth apparatus comprising: an outer process tube installed through a space; a nozzle for supplying a source gas to the space between the tubes; and a heater provided outside the outer process tube. . 2. The low-pressure vapor deposition apparatus according to claim 1, wherein the outlet of the nozzle is arranged in a space between the tubes from the other end side of the inner process tube. . 3. A low-pressure vapor-phase growth method using the low-pressure vapor-phase growth apparatus according to claim 1 or 2, wherein the heater is used to create an internal space of the inner process tube and a space between the tubes. A low pressure vapor phase growth method, characterized in that the raw material gas is supplied from the nozzle to the internal space through the space between the tubes while being heated to the film formation temperature to cause a vapor phase growth reaction on the sample surface.