JPS63164311A - Chemical vapor deposition method - Google Patents

Abstract

PURPOSE:To prevent the adhesion of a reaction product to the inner surface of a reaction container by a method wherein the gas having an etching effect on a reaction product is allowed to flow along the inner surface of the reaction container to be used for chemical vapor deposition. CONSTITUTION:An infrared ray lamp 6 is lighted up, raw gas is jetted out from the hole 8a of an outer tube 8 by controlling the flow rate of the raw gas by a flow-rate controller 11, and at the same time, etching gas (NF3 for example) is fed to a plasma generating device 12. Said etching gas is brought into a plasma state by applying high frequency voltage from a high frequency power source 13, and plasma etching gas is jetted out from the upper end hole of an inner tube 9 by adjusting the flow rate of gas by a flow-rate controlling valve 14. A grown is formed on a substrate by the reaction product such as Si and the like generated by the decomposition reaction of the raw gas. When a part of said reaction product is suspended and reaches in the vicinity of the inner surface of a reaction container 1, the adhesion of the reaction product to the inner surface of the reaction container is suppressed by the plasma etching gas flowing along the inner surface of the reaction container, the reaction product is washed away and discharged through a discharge hole 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of performing chemical vapor deposition by preventing reaction products from adhering to the inner surface of a reaction vessel or removing the adhering substances.

[Prior art]

Chemical Vapor Depth
During the growth reaction, the reaction products adhere to the inner surface of the growth reaction vessel, ie, wall-deposited silane is formed.

When this wall debossing (hereinafter abbreviated as wall debossing) occurs, the reaction products adhering to the inner surface of the reaction vessel block light from a substrate heating lamp etc. installed above it. This results in a decrease in reaction efficiency.

Furthermore, if the attached reaction products are peeled off and fall onto the substrate as particles, defects may occur in the grown film.

For this reason, in the past, depending on the state of adhesion of the reaction product to the reaction vessel after the reaction, for example, the adhesion thickness was 1Oμ-
When the chemical vapor deposition apparatus (hereinafter referred to as CvD apparatus) is separated and the reaction vessel is removed, the inner surface is etched with a mixed solution of, for example, nitrate M (HNO3) and hydronic acid (IP). Alternatively, after the reaction is completed without decomposition, a plasma-like etching gas is supplied into the reaction vessel to perform etching and remove deposits.

When removing the former reaction vessel from the CVO device, C
It takes about half a day to disassemble and assemble the vD device.

[Problem that the invention seeks to solve]

When removing deposits in this way, C
The vD apparatus could not be used for the reaction, which was a factor in reducing production efficiency.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a chemical vapor deposition method that can prevent wall deposits and improve production efficiency.

[Means for solving problems]

The present invention etches and removes reaction products present near the inner surface of a reaction vessel during chemical vapor deposition.

That is, the chemical vapor deposition method according to the present invention is characterized in that a gas having an etching effect on reaction products is caused to flow along the inner surface of a reaction vessel for chemical vapor deposition during chemical vapor deposition. .

[Effect]

In the present invention, the reaction product that has reached the vicinity of the inner surface of the reaction container is swept along the inner surface of the reaction container by the flowing etching gas, and if the reaction product adheres to the inner surface of the reaction container, the reaction product is removed. The kimono is etched with etching gas.

〔Example〕

The present invention will be specifically explained below based on the drawings.

The first WJ is a vertical cross-sectional view showing a state in which the present invention is implemented, and shows a reduced pressure CVO device, the reaction chamber of which is formed by covering a bottom plate 2 with a hemispherical shell-shaped transparent quartz reaction vessel 1. Inside the reaction vessel 1 there is a cylindrical support 3 that penetrates the bottom plate 2.
The upper part of the support column 3 is positioned so that the space between the support column 3 and the bottom plate 2 is airtight.

The pillar 3 has a rotational drive means (not shown) provided at its lower end.
An annular susceptor 4 having an inner diameter smaller than that of the support column 3 is concentrically provided at the upper end thereof.

A plurality of substrates 5.5 having a diameter shorter than the radial length of the susceptor 4 can be placed around its axis, and a plurality of substrates 5,5, etc., each having a diameter shorter than its radial length can be placed on the susceptor 4 outside the reaction chamber. Infrared lamps 6, 6, . . . are provided, and a reflecting plate 10 is further provided above them.

A double tube 7 is inserted into the inside of the support column 3, and the proximal end of the outer tube 8 is connected to a raw material gas source such as SiH4 (not shown), and the proximal end of the inner tube 9 is connected to the outer tube halfway. The etching gas is connected to a plasma generator 12 which passes through the wall 8 and converts the etching gas into plasma.

The upper end of the outer tube 8 passes through an opening in the center of the susceptor 4, and the space between the outer tube 8 and the opening of the susceptor 4 is airtight. An annular gas guide plate 8b is provided at the upper end of the outer tube 8 and has an outer diameter that does not cover the substrate 5 and an inner diameter that is the same as the outer diameter of the inner tube 9. An inner tube 9 is passed through the opening in the center in an airtight manner.

A plurality of holes 8a are provided in the outer tube 8 portion on the susceptor 4 in the circumferential direction at positions higher than the upper surface of the substrate 5 on which it is placed.

Bar... is opened, and source gas is ejected onto the substrate 5 from the hole 8a. The amount of raw material gas to be ejected is controlled by a flow rate controller 11 provided in the middle of the outer tube 8, and the raw material gas to be ejected is guided between the lower surface of the gas guide plate 8b and the upper surface of the susceptor 4, and spreads radially on the susceptor 4. The liquid flows and comes into contact with the upper surface of each substrate 5.

On the other hand, the upper end of the inner tube 9 is positioned a little lower than the height of the inner surface of the reaction vessel l facing it, so that the plasma etching gas generated by the plasma generator 12 reaches the tip of the inner tube 9. It is now gushing more. At the upper end of the inner tube 9, an annular gas guide plate 9b having an outer diameter smaller than that of the gas guide plate 8b and having an inner diameter of the same size as the outer diameter of the inner tube 9 has its upper surface at the same height as the upper end. The plasma etching gas ejected from its upper end port is guided between the upper surface of the gas guide plate 9b and the inner surface of the reaction vessel 1, spreads radially, and as a result flows along the inner surface of the reaction vessel 1. .

The plasma etching gas is supplied to the plasma generator 12.
It is generated by supplying an etching gas such as NF3 to the etching gas and applying a high frequency voltage of, for example, 13.56 Hz from the high frequency power source 13 to the etching gas, and the amount of the ejected gas from the tip of the inner tube 9 reaches the middle of the inner tube 9. The flow rate is adjusted by the provided flow rate adjusting pulp 14.

The bottom @2 has a plurality of gas exhaust holes 15.15. ... are opened, and source gas and plasma etching gas are discharged from these gas discharge holes 15.

The chemical vapor deposition method according to the present invention is carried out as follows using the low pressure CVD apparatus configured as described above.

First, a plurality of substrates 5 for base materials are placed on the susceptor 4, and the inside of the reaction chamber is maintained under a reduced pressure of, for example, I Torr or less.

When such preparation is completed, the infrared lamp 6 is turned on,
In addition, a flow rate controller 11 controls the flow rate of the raw material gas from the raw material gas source.
At the same time, the source gas is ejected from the hole 8a of the outer tube 8, and the etching gas (for example, NF3) is supplied to the plasma generator 12, and a high frequency voltage is applied from the high frequency power source 13 to turn the etching gas into plasma. The plasma etching gas is blown out from the upper end of the inner tube 9 by adjusting the flow rate with the flow rate adjustment valve 14.

Through this treatment, for example, S produced in the decomposition reaction of the raw material gas
A grown film is formed on the substrate by reaction products such as t.

If a part of this reaction product floats and reaches the vicinity of the inner surface of the reaction container 1, the reaction product is prevented from adhering to the inner surface of the reaction container by the plasma etching gas flowing along the inner surface of the reaction container 1. It is washed away and discharged from the discharge hole 15.

Further, if the reaction product adheres to the inner surface of the reaction vessel, the adhered substance is etched away by plasma etching gas.

As described above, in the case of the present invention, film growth and etching are performed simultaneously in the reaction vessel, so the plasma generation device 1 is
The pressure Pe of 2 and the pressure Pd inside the reaction vessel 1 are P during the reaction.
The pressure of the source gas supplied to the outer tube 8 and the pressure of the etching gas supplied to the plasma generator 12 are controlled by appropriate means so that e≦Pd. Even if mixed into the raw material gas, the substrate 5
In this case, film growth and etching occur simultaneously, and the film properties are not adversely affected.

Therefore, according to the present invention, it is possible to substantially prevent the occurrence of wall deposits and grow a high quality film.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention, in which the same parts as in FIG. 1 are given the same numbers. In this embodiment, plasma etching gas generated by a plasma generator 12 is supplied into the reaction vessel l through a hole 20 formed at the zenith of the reaction vessel 1, and is placed parallel to the susceptor 4, facing the hole 20. The supplied plasma etching gas is guided by the upper surface of a disk-shaped gas guide plate 21 provided inside the reaction vessel 1 and the inner surface of the reaction vessel 1 so that it flows along the inner surface of the reaction vessel 1. Similar effects can be obtained in this case as well.

In the above description, the present invention is carried out using a low-pressure CVD apparatus in which the reaction is carried out by reducing the pressure inside the reaction container, but the present invention is not limited to this, and the present invention can also be carried out using a CVD apparatus that does not perform pressure reduction or other types of CVD apparatuses. It is also possible in some cases.

Further, in the above description, the substrate is heated using an infrared lamp, but the present invention is not limited to this, and can be implemented even when using other heating means.

Furthermore, the present invention is not limited to plasma etching gases, but also CV etching gases.
D Depending on the type of apparatus, the type of source gas, etc., other etching gases may also be used.

〔effect〕

As detailed above, according to the present invention. In some cases, the occurrence of wall debos can be practically prevented, so etching and cleaning of the reaction vessel are completely unnecessary, which can greatly reduce the downtime of the CVD equipment and improve production efficiency.
Furthermore, since the reaction products adhering to the inner surface of the reaction vessel are not peeled off and fall as particles onto the grown film, the present invention has excellent effects such as forming a high quality grown film on the substrate.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the invention.

Claims (1)

[Claims] 1. A chemical vapor deposition method characterized by flowing a gas having an etching effect on reaction products along the inner surface of a chemical vapor deposition reaction vessel during chemical vapor deposition.