JPH04369833A - Thin film manufacturing method and device - Google Patents

Abstract

PURPOSE:To control the flow rate of a gasified gas for stabilizing the thin film formation by a method wherein, during the chemical deposition process such as CVD, etc., using a liquid or solid material, an ultrasonic oscillator is provided on the outer wall of a vessel containing the material so as to control the power supplied for the oscillator. CONSTITUTION:Within the title thin film manufacturing device, the space between a metallic, e.g. stainless steel etc., container 14 and an electrode plate 18 is impressed with a voltage using an ultrasonic generating piezoelectric ceramic element 17 so that the ultrasonic ware may be propagated in the stainless steel container thereby enabling the flow rate of the gas produced in a flow rate measuring instrument 19 and led-into a reaction vessel 11 to be directly measured while the measured values as control signal power through an amplifier circuit 20 may be supplied for an ultrasonic oscillator so as to be adjusted to the set up flow rate thereby enabling the flow rate to be precisely controlled.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a thin film manufacturing method and thin film manufacturing method using chemical vapor deposition methods such as plasma CVD (chemical vapor deposition), thermal CVD, and photoCVD using source gases obtained by vaporizing liquids and solids. Regarding equipment.

0002

[Prior Art] Conventionally, when a liquid raw material or a solid raw material is used for forming a thin film by plasma CVD, for example,
The gas supply device generally has a configuration as shown in FIG. In FIG. 3, numeral 31 denotes a reaction vessel for chemical vapor phase thin film growth by decomposing a source gas using energy such as heat, plasma, light, etc., and is generally evacuated to a vacuum through an exhaust hole 32. 33 is a container for liquid raw material or solid raw material, and the container and raw material 34 are heated and vaporized by a heater 38. For example, when forming a tantalum oxide thin film, solids such as TaCl5, TaF5, Ta(OC2
A liquid raw material such as H5)5, Ta(OCH3)5, etc. may be placed in a container. The vapor is used as a reaction gas by directly introducing it into a vacuum chamber or by bubbling it with an inert carrier gas such as Ar or He. 3
Reference numeral 5 denotes a carrier gas container, which is introduced into the liquid or liquefied by heating through piping, and vaporization is promoted by bubbling. The amount of raw material introduced into the reaction vessel 31 was controlled by adjusting the flow rate of the carrier gas and setting the heating of the raw material container using the flow rate control device 36. Reference numeral 37 denotes a gas introduction hole, where the vaporized raw material gas is kept warm by a pipe heater 39, and an oxidizing gas such as O2, N2 O, etc. is introduced through a second gas introduction hole 38. These gases are plasma decomposed and deposited as a thin film on the substrate 41 on the substrate holder 40.

0003

[Problems to be Solved by the Invention] However, in such a conventional device configuration, even if flow rate control is attempted, the raw material gas is heated, so the mass flow controller cannot directly control the raw material gas, and the carrier gas The amount of raw material introduced into the reactor was controlled by adjusting the flow rate and heating the raw material container. Therefore, the flow rate varied depending on the shape and capacity of the vaporizer (liquid container), and the remaining amount of raw material, resulting in a lack of reproducibility in film formation. As a result, it has been difficult to put it into practical use as a process for forming capacitors in VLSIs. In addition, due to the demand for processing large-area substrates, it is necessary to uniformly supply vaporized raw material gas to the reaction region due to the increase in the size of the reaction vessel and the diameter of the plasma electrode. For this purpose, sufficient vaporization is required, and the heating temperature of the raw material container and piping system must be further increased, making flow rate control even more difficult, which has hindered practical application in production equipment.

SUMMARY OF THE INVENTION In order to solve the problems of the prior art described above, it is an object of the present invention to accurately control the flow rate of source gas and improve the film thickness distribution for each deposition.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the thin film manufacturing method of the present invention gasifies a liquid or solid raw material, applies energy to the gas to decompose it, and performs chemical vapor phase deposition to form a thin film. In the manufacturing method, an ultrasonic vibrator is installed on the outer wall of a container containing the raw material, applying ultrasonic vibration with a wavelength that can be absorbed by the molecules of the raw material, and adjusting the power applied to the vibrator. , the flow rate of the gasified gas is controlled.

[0006] In the above configuration, it is preferable to apply ultrasonic waves to the liquid or solid raw material container and simultaneously control the flow rate of the gasified gas by heating. Further, the thin film manufacturing apparatus of the present invention is an apparatus for manufacturing a thin film by gasifying a liquid or solid raw material, applying energy to the gas to decompose it, and depositing it in a chemical vapor phase. The apparatus is characterized in that it is equipped with an ultrasonic vibrator for gasifying the raw material, and also includes power adjustment means for applying power to the vibrator for controlling the flow rate of the gas to be gasified.

[0007]

[Function] The function of the present invention is as follows. First, through the vaporization or liquefaction of the liquid or solid raw material used for thin film deposition, and then in the thin film deposition process by the chemical vapor deposition process of the vaporized gas, the raw material is It is possible to vaporize the gas without raising the temperature to a high temperature. As a result, the flow rate of the raw material gas can be measured stably, and furthermore, it can be controlled quickly by controlling the power supplied to the ultrasonic transducer. As a result, it has the effect of realizing a method for stably forming a high-quality thin film over a large area with good controllability.

[0008]

[Example] Unlike the conventional thin film forming apparatus or method that utilizes only heating vaporization of raw materials, the present invention employs a thin film deposition process using chemical vapor deposition through liquefaction of liquid or solid raw materials used for thin film deposition. By installing an ultrasonic vibrator in the container and exciting the liquid with so-called ultrasonic waves, vaporization is performed at low temperatures at the liquid surface of the raw material liquid or the liquid obtained by liquefying the solid material, and the amount of vaporization is further increased. The flow rate can be adjusted with good controllability by adjusting the power supplied to the sonic vibrator. As a result, the present invention provides an apparatus configuration and a forming method for stably forming a high-quality thin film over a large area with good controllability.

In the present invention, an electric flow rate measuring device is disposed in the gas introduction pipe between the liquid gasification container and the thin film forming container,
It is preferable to have an electrical feedback circuit for controlling the output of the ultrasonic transducer so that the flow rate is constant according to the set flow rate, so that the flow rate can be controlled to any desired flow rate.

Further, in the present invention, it is preferable that the frequency of the ultrasonic waves applied to the liquid container is 10 kHz to 1 MHz of ultrasonic vibration. Based on the drawings below,
1 shows a typical embodiment of the present invention.

FIG. 1 is a schematic diagram of a liquid raw material gasification apparatus, a gas supply apparatus using the same, and a thin film forming system configuration used in the present invention. In FIG. 1, 11 is a reaction vessel for forming a thin film, and has a structure that can be evacuated to a vacuum through an exhaust hole 12. 13 is the first gas introduction port;
The vaporized raw material gas can be introduced from the raw material supply device of the present invention. 14 is a container for liquid raw materials or solid raw materials, and the container and raw material 1 are heated by the heater 15.
6 is not directly vaporized, but is heated to a range that can be detected by a flow rate detector. For example, when forming a tantalum oxide thin film, Ta(OC2 H5)5, Ta(OCH3
) 5, etc., the temperature may be raised to about 150° C., which is a temperature range that does not vaporize but allows flow rate detection. Reference numeral 17 denotes a piezoelectric ceramic element for generating ultrasonic waves for transmitting ultrasonic vibrations to the raw material container.The raw material container 14 is made of a metal container such as stainless steel, and is fixed to the container via electrodes as shown in FIG. Ultrasonic waves are generated by applying a voltage between the raw material container 14 made of stainless steel or the like and the electrode plate 18, and the ultrasonic waves are propagated to the stainless steel container. By adjusting the power applied to the electrodes, the output of the ultrasonic waves generated can be varied, thereby controlling the amount of liquid vaporized. Reference numeral 19 denotes a flow rate detector, which can directly measure the flow rate of gas generated from the raw material container and introduced into the reaction container. The measured value is passed through the amplifier circuit 20 as a control signal, and power is applied to the ultrasonic transducer through the high-frequency power source 21, and by making the power adjustable so that the set flow rate is achieved, accurate flow rate control becomes possible. Reference numeral 22 denotes a second gas introduction hole through which gas such as N2O, O2, or a mixture thereof is introduced, which is mixed with the Ta raw material gas in the reaction chamber, and caused to decompose the substrate 24 on the substrate holder 23 through various decomposition reactions. A thin film is formed.

[0012] In this embodiment, the apparatus configuration for tantalum oxide was described, but similar effects can be obtained as a raw material gasification apparatus for thin film formation using other liquid raw materials or liquefied solid raw materials. Needless to say.

The effects of this embodiment are as follows. Figure 2 shows two cases in which a tantalum oxide thin film was formed by supplying the raw material gas by bubbling, using a carrier gas He as a conventional method, with the heater temperature of the raw material container set at 130°C, and a case in which the raw material gas was directly measured without bubbling. A comparison of the film thickness distribution when a tantalum oxide thin film according to the present invention was formed under controlled conditions and deposited multiple times on different substrates under the same conditions is shown. The horizontal axis shows the number of depositions, and the vertical axis shows the film thickness value normalized by the initial deposited film thickness. This figure 2
As is clear from the above, according to the present invention, the film thickness distribution for each deposition is significantly improved.

[0014]

As explained above, according to the present invention, an ultrasonic vibrator is installed on the outer wall of a container housing a vaporized or liquefied liquid or solid raw material used for thin film deposition, and By applying ultrasonic vibration with a wavelength that can be absorbed by molecules and adjusting the power applied to the vibrator, it is possible to vaporize the raw material gas without raising the temperature to a high temperature. As a result, the flow rate of the raw material gas can be measured stably, and furthermore, by controlling the power supplied to the ultrasonic transducer, rapid control is possible. As a result, it is possible to realize a method for stably forming a high-quality thin film over a large area with good controllability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a gas supply device using a liquid raw material gasification device according to an embodiment of the present invention.

FIG. 2 shows a comparison of the film thickness change distribution depending on the number of depositions when a tantalum oxide thin film was formed by the conventional method and when a tantalum oxide thin film was formed by the present invention, in order to show the effect of one embodiment of the present invention. FIG.

FIG. 3 is a schematic external view of a conventional thin film device.

[Explanation of symbols]

11 Vacuum chamber 12 Exhaust hole 13 First gas introduction hole 14 Raw material container 15 Heater 16 Raw materials 17 Piezoelectric ceramic element 18 Electrode plate 19 Flow rate measuring device 20 Amplifier circuit 21 High frequency power supply 22 Second gas introduction hole 23　　　　　Substrate holder 24 Board

Claims (3)

[Claims] 1. A method for manufacturing a thin film by gasifying a liquid or solid raw material and applying energy to decompose the gas while depositing it in a chemical vapor phase, in which an ultrasonic vibrator is attached to the outer wall of a container containing the raw material. A thin film manufacturing method characterized in that the flow rate of the gasified gas is controlled by installing an ultrasonic vibration having a wavelength that can be absorbed by the molecules of the raw material and adjusting the electric power applied to the vibrator. . 2. The thin film manufacturing method according to claim 1, wherein the ultrasonic wave is applied to the liquid or solid raw material container, and at the same time, the flow rate of the gasified gas is controlled by heating. 3. In an apparatus for manufacturing a thin film by gasifying a liquid or solid raw material, applying energy to the gas to decompose it, and performing chemical vapor deposition, the raw material is deposited on the outer wall of a container containing the raw material. What is claimed is: 1. A thin film manufacturing apparatus comprising: an ultrasonic vibrator for gasifying the gas; and a power adjustment means for controlling the flow rate of the gas to be gasified.