JPH05132780A - Method for forming thin film and device therefor - Google Patents

Abstract

PURPOSE:To stably form a uniform thin film on a substrate in a vacuum chamber by chemical vapor deposition by removing the gas remaining in the vacuum chamber immediately after the thin film forming reaction is finished. CONSTITUTION:A substrate 33 of polysilicon, etc., is fixed to a holder 34 in the vacuum chamber 21 of a chemical vapor deposition device and heated to a specified temp. by a heater 35, the chamber 21 is evacuated by a first exhaust pipe 23, and the liq. material in an ampule 25 is heated in a thermostatic bath 26 and vaporized. An inert gas such as Ar is blown into the liq. material from a cylinder 27 and bubbled, the vapor is introduced into the chamber 21 through a pipe 32, and O2 gas is simultaneously supplied to the chamber 21 from a cylinder 29 through a pipe 32 to form the thin film of the oxide of the raw material on the substrate 33 by a vapor-phase reaction. The waste gas is removed from the first exhaust pipe 23 during the thin film forming reaction, the supply of gases from the cylinders 27 and 29 is stopped immediately after the reaction is finished, the unreacted gas in the chamber 21 is rapidly removed from a second exhaust pipe 24 to prevent the further growth of the thin film, and an oxide film uniform in thickness is formed at all times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus and a thin film forming method for forming a thin film using a material (liquid material) having a low vapor pressure in CVD (chemical vapor deposition).

[0002]

2. Description of the Related Art As a conventional liquid material, Ta (OC)
₂H_Five)_FiveWhen forming a tantalum oxide thin film using
I will show you. The tantalum oxide thin film has the structure shown in FIG.
Has been formed by the device. The vacuum chamber 5 is a vacuum exhaust device.
Evacuated to vacuum by 9. Polysilicon, WSi, etc.
Substrate 10 is heated to a suitable temperature (200-
It is fixed to the substrate holder 11 heated to 650 ° C.
He, Ar, etc., whose flow rate is controlled by the flow rate control device 1,
The inert gas 2 (flow rate 100-10000 sccm) is constant.
The temperature is controlled (80-200 ° C) by the hot bath 3.
Ta (OC in pull 4 ₂H_Five)_FiveBubbling the heater
Gas introduction tube 1 heated by 8 (80-400 ° C.)
It is introduced into the vacuum chamber 5 through 3. On the other hand, the flow control device
Oxygen-containing gas 7 such as oxygen whose flow rate is controlled by the device 6.
(100-10000 sccm) is also applied to the heater 8 at the same time.
Therefore, the gas introduction pipe 13 heated (80-400 ° C.)
It was introduced into the vacuum chamber 5 and the raw material gas was heated.
Reacts in the vicinity of the substrate 10 and forms a tantalum oxide thin film on the substrate 10.
Is formed. The gas introduced into the vacuum chamber 5 is evacuated.
It is evacuated by the device 9 and the appropriate pressure (0.5-10T
orr).

[0003]

However, in the thin film forming apparatus according to the conventional example, when a material having a low vapor pressure such as a liquid is used as the raw material gas, even if the introduction of the gas is stopped in order to complete the thin film formation, the gas is stopped. The liquid material that slightly adheres to the introduction port or the gas introduction pipe is introduced into the vacuum chamber, so that the deposition of the thin film proceeds. Therefore, there is a problem that a uniform thin film cannot be formed with good controllability.

An object of the present invention is to provide a thin film forming apparatus capable of forming a uniform thin film with good controllability in consideration of the problems of the conventional thin film forming apparatus.

[0005]

The apparatus according to the present invention is provided with a gas introduction port at the same time as or after the completion of the deposition from the gas introduction port, separately from the gas exhaust port for exhausting the gas introduced into the vacuum chamber during the deposition. A gas exhaust pipe for exhausting the vacuum chamber to a vacuum is connected to the gas introduction pipe.

[0006]

In the present invention, the vacuum chamber can be evacuated from the gas inlet, and the gas inlet tube and the inside of the gas inlet can be directly evacuated to a vacuum without passing through the vacuum chamber containing the sample. The deposition of the thin film can be stopped at an instant.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of an embodiment of a thin film forming apparatus according to the present invention.

A first vacuum exhaust pipe 23 is provided on the upper wall of the vacuum chamber 21.
And a gas introduction pipe 32 is connected to the bottom wall, and a second vacuum exhaust pipe 24 is connected in the middle of the gas introduction pipe 32. Those first vacuum exhaust pipe 23
The second vacuum exhaust pipe 24 is connected to the vacuum exhaust device 22. In the vacuum chamber 21, a substrate holder 34,
A substrate 33 made of polysilicon, WSi or the like held by the substrate holder 34, and a heater 35 for heating the substrate holder 34 are arranged so as to hang from the upper wall. In addition, the gas introduction pipe 32 is used as a raw material liquid Ta (OC).
₂ H ₅ ) ₅ is connected to the stored ampoule 25. In addition, a tube from a cylinder 27 containing an inert gas such as Ar is inserted into the bottom of the ampoule 25 via a flow rate control device 28. The ampoule 25 is heated by a constant temperature bath 26 to a temperature at which it is easily vaporized.
The liquid in the ampoule 25 is bubbled by the inert gas sent from the cylinder 27.

Further, the cylinder 29 containing an oxygen-containing gas such as O ₂ has a gas introduction pipe 32 through a flow control device 30.
Connected to the vacuum chamber 21. Reference numeral 31 is a heater for heating the inert gas and the vaporized raw material.

Next, the operation of this embodiment will be described.

The vacuum chamber 21 is evacuated to a vacuum by a vacuum exhaust device 22 through a first vacuum exhaust pipe 23 and a second vacuum exhaust pipe 24. Ta (OC ₂ H ₅ ) ₅ in the ampoule 25 is heated by the constant temperature bath 26 to a temperature at which it easily vaporizes. The flow rate of the inert gas such as Ar in the cylinder 27 is controlled by the flow rate control device 28. The inert gas whose flow rate was controlled bubbled Ta (OC ₂ H ₅ ) ₅ in the ampoule and passed through the gas introduction pipe 32 heated by the heater 31 together with vaporized Ta (OC ₂ H ₅ ) _5. It is introduced into the vacuum chamber 21.

On the other hand, the oxygen-containing gas such as O ₂ in the cylinder 29 is introduced into the vacuum chamber 21 after the flow rate is controlled by the flow rate control device 30. Substrate 3 made of polysilicon, WSi, etc.
3 is fixed to the substrate holder 34 and heated by the heater 35 to a temperature suitable for deposition. The gas introduced into the vacuum chamber 21 undergoes a thermal decomposition reaction near the surface of the substrate 33, and a tantalum oxide thin film is formed on the substrate 33. During the deposition, the introduced gas is exhausted from the first vacuum exhaust pipe 23, and at the same time as the deposition is completed, the residual gas is exhausted from the second vacuum exhaust pipe 24 connected near the rear part of the gas introduction.

Table 1 shows the difference in film thickness when a tantalum oxide thin film is formed by the conventional example and the thin film forming apparatus according to the present invention.

[0015]

[Table 1]

In condition 1 in the table, the temperature of the substrate 33 is drastically reduced immediately after the tantalum oxide thin film is formed. In condition 2, after the tantalum oxide thin film is formed, the gas introduction is stopped and the substrate 33 is left as it is for 30 minutes and then the substrate 33. This is the case when the temperature is lowered. In the case of the tantalum oxide thin film according to the conventional example, the film thickness is 1 under the condition 1.
030Å, whereas in case of condition 2, 1240Å
It has become. However, in the case of tantalum oxide according to the present invention, the film thickness is 1020Å under the condition 1, and the condition 2
In the case of, it turns out to be 1040Å, which is almost unchanged.

In this embodiment, the vacuum exhaust device is also used, but
The same effect can be obtained by installing a vacuum exhaust device for exhausting gas during deposition and a vacuum exhaust device for exhausting the vacuum chamber after completion of deposition.

[0018]

As is apparent from the above description, according to the present invention, the residual gas and the like adhering to the gas introducing pipe can be exhausted without passing through the vacuum chamber in which the substrate is installed.
It has an advantage that a thin film can be formed with good controllability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of a thin film forming apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an outline of a conventional tantalum oxide thin film forming apparatus.

[Explanation of symbols]

 1 Flow Control Device 2 Cylinder 3 Constant Temperature Tank 4 Ampoule 5 Vacuum Chamber 6 Flow Control Device 7 Cylinder 8 Heater 9 Vacuum Exhaust Device 10 Substrate 11 Substrate Holder 12 Heater 13 Gas Introducing Tube 21 Vacuum Chamber 22 Vacuum Exhaust Device 23 First Vacuum Exhaust Pipe 24 Second Vacuum Exhaust Pipe 25 Ampoule 26 Constant Temperature Tank 27 Cylinder 28 Flow Control Device 29 Cylinder 30 Flow Control Device 31 Heater 32 Gas Inlet 33 Substrate 34 Substrate Holder 35 Heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Hirao 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A thin film forming apparatus for forming a thin film by introducing a raw material gas into a vacuum chamber, applying heat from the outside, and thermally decomposing it, and at least a first vacuum exhaust pipe directly connected to the vacuum chamber; A thin film forming apparatus comprising: a second vacuum exhaust pipe connected to a gas introducing pipe for introducing gas into the chamber. 2. A thin film forming method for forming a thin film by introducing a raw material gas into a vacuum apparatus, applying heat from the outside, and thermally decomposing the first gas, while the gas is being introduced into the vacuum chamber. The second vacuum exhaust connected to a gas introduction pipe for introducing gas into the vacuum chamber while exhausting the gas, stopping the exhaust from the first vacuum exhaust pipe at the same time as or before and after the end of the gas introduction. A method for forming a thin film, characterized in that gas is exhausted from a tube.