JP2568224B2 - Gas-phase chemical reaction material supply method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for supplying raw materials when a thin film or powder is produced by a gas phase chemical reaction method.

[Prior Art and Problems] The vapor-phase chemical reaction method is usually called a CVD method, and a highly pure and homogeneous thin film, powder or bulk material can be obtained. Therefore, it is used for electronic materials such as semiconductor devices and optical fibers. It is used in various fields such as surface modification of optical materials such as base materials and metal materials, or production of raw materials for ceramics. In such a gas phase chemical reaction method, a gas of a raw material or a material that reacts with the raw material is introduced into a reaction furnace in a state, and a target compound, metal or non-metal thin film is formed by decomposition or chemical reaction of the raw material gas. ,
It is a method for producing powder or bulk.

As the above-mentioned raw material, a target compound or a compound containing a simple constituent element is used. The raw material may be a gas at room temperature, but a liquid or solid substance may also be used. In the case of a gaseous raw material, it can be directly supplied to the reaction furnace from a high pressure gas container or the like.

The liquid or solid substance is heated to gas and introduced into the reaction furnace. At this time, when the heated raw material has a sufficient vapor pressure, it can be used as it is as a raw material for a gas phase chemical reaction due to its own vapor pressure. On the other hand, when the vapor pressure is low, an inert gas is used as a carrier gas to flow so as to come into contact with the heated raw material, and the vapor of the raw material is pushed away to be supplied to the reactor as a mixed gas containing the raw material. It The feed rate of the raw material vapor at this time is determined by the vapor pressure by heating the raw material and the flow rate of the carrier gas. In order to increase the supply rate of the mixed gas containing the vapor of the raw material, a method of increasing the vapor pressure of the raw material or a method of increasing the flow rate of the carrier gas has been conventionally used.

As a method of increasing the vapor pressure of the raw material, the heating temperature of the raw material is increased. However, some raw materials have inherently low physical properties and have a low vapor pressure, and when they are heated at a high temperature, some of them decompose without forming vapor, so that the method of raising the heating temperature is naturally limited. Further, from the viewpoint of heat resistance of the parts used in the device, heating at high temperature is limited.

With the method of increasing the flow rate of the carrier gas, the supply rate can be increased to some extent. However, there are problems that the temperature of the vaporizer is lowered by the carrier gas, or the vapor velocity of the raw material does not catch up with the flow rate of the carrier gas and the vapor efficiency is lowered. In addition, when the flow rate of the carrier gas is increased, it may be supplied to the reaction furnace in the form of droplets or the like instead of the vapor of the raw material, and the uniformity of the product may be deteriorated. Further, since the carrier gas is generally a substance that is not directly involved in the gas phase chemical reaction, there are problems such as a decrease in the concentration of the raw material and an increase in the reaction pressure more than necessary.

On the other hand, as a raw material, a target compound, a halide of a single component element, a hydride, or a compound having a bond with an organic group is generally used. When a halide is used, it is inexpensive, but its vapor pressure is low, and its supply rate is limited for the reasons described above. Some compounds with a bond with hydrides and organic groups have higher vapor pressure than halides, but these substances are expensive and reactive and difficult to handle. was there.

The present invention has been made to solve the above conventional problems, and when supplying an inexpensive halide raw material to a vapor phase chemical reaction apparatus by a carrier gas, improves the supply rate of the halide raw material. It is meant to provide a way to get.

[Means for Solving the Problems] The present invention provides a method of supplying a halide vapor to a vapor phase chemical reaction apparatus by passing a carrier gas through a heated halide, wherein the vapor of alcohols is previously added to the carrier gas. The method for supplying a raw material for a gas phase chemical reaction is characterized by including:

The above-mentioned halide is, for example, a metal or non-metal fluoride, chloride, bromide or iodide, specifically B
_{F 3, BCl 3, AlCl 3} , SiCl 4, TiCl 4, MgCl 2, GeCl 4, ZrCl 4
Etc. can be raised. Also included are compounds in which some of these halogen atoms have been replaced with other atoms, such as SiH ₂ Cl ₂ . The temperature for heating these halides varies depending on the physical properties of the raw materials used, the structure and material of the vaporizer, etc., but may be in the range of -50 ° C to 1300 ° C.

As the carrier gas, an inert gas having low reactivity with the raw material is usually used. Specifically, nitrogen, argon, helium, or the like can be given, and hydrogen or oxygen may be used depending on the case.

Examples of the alcohols to be contained in the carrier gas in advance include, for example, the general formula ROH (wherein R is a carbon number of 1 to 20).
(Indicating an alkyl group, an alkenyl group, and an aryl group). As a method of including these alcohols in the carrier gas, for example, a method of contacting the carrier gas with the alcohols is adopted. Generally, a bubbling method in which a carrier gas is injected into a liquid alcohol by a nozzle is adopted. The temperature at this time is from room temperature to the boiling point of the alcohol used.

As the vapor phase chemical reaction device, a general CVD reaction device is used, the pressure system is a reduced pressure or normal pressure system,
As the excitation method, thermal excitation, plasma excitation or optical excitation is adopted.

[Operation] According to the present invention, a halide raw material having a low vapor pressure can be supplied at a higher rate than in the conventional case. Also, in the gas phase chemical reaction, a good reaction can be achieved at a temperature lower than the normal reaction temperature.

That is, by supplying a carrier gas containing alcohols in advance to a halide raw material heated in a vaporizer or the like, alcohol (ROH) reacts with halide (MX) as follows to generate an alkoxide. Occur.

MXn + m ・ ROH → M (OR) mXn−m + m → HX Actual formation of alkoxide in the above formula has not progressed completely, and the raw material supplied to the gas phase chemical reaction is a mixture of halide and alkoxide. Is considered to be.
The coexistence of the vapor of the halide and the alkoxide increases the substantial concentration of the constituent elements in the gas phase, and thus the supply rate of the halide can be increased. Moreover, it becomes possible to decompose at a lower temperature than the halide alone. Further, by supplying the mixed gas to the vapor phase chemical reaction apparatus, alkoxides are decomposed at a lower temperature when solid is produced from the vapor phase which progresses due to nucleation and nuclear growth in the vapor phase reaction in the apparatus. Since the nucleation reaction is promoted, a dense thin film or fine powder can be produced.

Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

First, a quartz substrate 3 having a size of 10 mm × 10 mm × 2 mm is held on a substrate holder 2 arranged in the reactor 1 having a diameter of 50 mm, and then the gas in the reactor 1 is evacuated through an exhaust pipe 4. The internal pressure was adjusted to 20 torr and further heated to 100 ° C. by the electric furnace 5. Subsequently, the first vaporizer 6 kept at 50 ° C. in a constant temperature bath (not shown) and containing t-butyl alcohol contained argon as a carrier gas in the first open state.
Bubbling was performed through the valve 7a at a rate of 160 cc / min. Subsequently, argon gas containing t-butyl alcohol is heated to 250 ° C. by the electric furnace 8 through the second valve 7b in the open state, and is transferred to the second vaporizer 11 in which the quartz boat 10 containing the zirconium chloride 9 is arranged. Supplied. Next, the argon gas that has passed through the second vaporizer 11 is supplied to the reaction furnace 1, and a mixed gas of hydrogen and carbon dioxide (mixing ratio 1: 1) from another system is supplied to the reaction furnace 1 at 80 cc /
The substrate holder 2 in the reactor 1 is supplied simultaneously under the condition of min.
A zirconium oxide thin film was formed on the upper substrate 3. As a result, a zirconium oxide thin film having a thickness of 10 μm was formed by the reaction for 1 hour.

Comparative Example 1 Quartz containing zirconium chloride 9 heated to 250 ° C. in an electric furnace 8 through the third valve 7c through argon gas (flow rate 160 cc / min) as a carrier gas with the first and second valves 7a and 7b closed. A zirconium oxide film was formed in the same manner as in the example, except that the boat 10 was directly supplied to the second vaporizer 11 in which the boat 10 was arranged. As a result, a 4 μm thick zirconium oxide thin film was formed by the reaction for 1 hour.

Comparative Example 2 The first and second valves 7a and 7b were closed, and the third valve 7c was operated under the condition that the flow rate of argon gas as a carrier gas was 250cc / min.
A zirconium oxide film was formed in the same manner as in the example, except that it was heated to 250 ° C. by the electric furnace 8 and directly supplied to the second vaporizer 11 in which the quartz boat 10 containing the zirconium chloride 9 was placed. I did. As a result, a zirconium oxide thin film having a thickness of 6 μm was formed by the reaction for 1 hour.

From the above results, it is understood that the film formation rate of zirconium oxide can be remarkably improved by preliminarily including alcohol vapor in the carrier gas as in the present invention.

[Effects of the Invention] As described in detail above, according to the method for supplying a vapor phase chemical reaction raw material of the present invention, when an inexpensive halide raw material is supplied to a vapor phase chemical reaction apparatus by a carrier gas, the halide It has a remarkable effect that the feed rate of the raw material can be improved, and the gas phase chemical reaction can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a film forming apparatus used in Examples and Comparative Examples of the present invention. 1 ... Reactor, 2 ... Substrate holder, 3 ... Quartz substrate,
5, 8 ... Electric furnace, 6 ... First vaporizer, 9 ... Zirconium chloride, 11 ... Second vaporizer.

Claims (1)

(57) [Claims] 1. A method for supplying a vapor of a halide to a vapor phase chemical reaction apparatus by passing a carrier gas through a heated halide, wherein the vapor of alcohols is contained in advance in the carrier gas. Method of supplying raw material for phase chemical reaction.