JPH04168277A - Thin film forming apparatus and thin film forming method - Google Patents

Abstract

PURPOSE:To obtain a high-quality film which is free from cracks and voids by ultrasonically evaporating a soln. contg. a organometallic compd. and cracking the vapor thereof by heating to form the film of the metal oxide corresponding to the above-mentioned compd. on the surface of a base material. CONSTITUTION:This thin film forming device is formed of means 1, 5 for ultrasonically evaporating liquid 2 contg. the organometallic compd., gas introducing means 3, 4, a means for transporting the evaporated gas, a means 7 for holding the base material 8, and a means 6 for heating the base material 8. The above-mentioned liquid 2 is evaporated by using the above-mentioned devise and the vapor thereof is cracked by heating to form the thin film of the metal oxide corresponding to the above-mentioned organometallic compd. on the base material 8. The organometallic compd. arrives at the base materials 8, 11 in the form that the organometallic compd. does not contain an org. solvent and, therefore, the formation of the film forming components to gigantic particles before baking is prevented and the high-quality thin film free from the cracks 12 and voids 13 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thin film forming apparatus and a thin film forming method, and more particularly to an apparatus and method suitable for forming a metal oxide thin film.

[Prior art] In recent years, metal alkoxides and other metal organic compounds (
Metallo-organic compounds
) have been used to create metal oxides, composite metal oxides, and glass bodies, and in particular, granules or bulk bodies of ceramic materials and fibers used in optical fibers have been put into practical use. This production technique is generally called a sol-gel method, and is classified as a liquid phase reaction in contrast to a gas phase reaction system using a vacuum such as sputtering. Sol-
Advantages of the gel method include generally being able to lower the process temperature, controlling the composition and creating ceramics and glasses with new compositions, and having good throughput.

As an example of the sol-gel method, see H, Dilich; J, N
on-Crystal 5olids 57 (1983
) 371-388, Kiyoo Sakuhana; The Fourth
International Workshop on
Glassesand Glass-C:eram
ics from Ge1s, Kyoto, Jul
y13-15.1987, etc., all of which are methods in which a precursor is applied to a substrate and then heated and fired.

[Problem to be solved by the invention] However, in the above method, the problem as shown in FIGS. 2(a) and (b)
In the process shown in FIG. 3, the thin film-forming components in the wet gel layer formed on the base material 11 by a spin cord or the like are crystal particles as shown in FIGS. 3(a), (b), and (c). 21. They are primary particles 22 and aggregated particles 23, and even if they are heated and fired, a volume change may occur due to evaporation of the organic solvent and sintering of the aggregated particles, as shown in Figure 1 (b). As shown in FIG. The purpose is to provide a thin film forming apparatus and method that can form a thin film without voids or cracks while retaining the advantages of the sol-gel method as described above. be.

[Means for Solving the Problems] The thin film forming apparatus of the present invention includes a vaporizing means for vaporizing a liquid using ultrasonic waves, a gas introducing means for introducing a carrier gas, and a carrier gas that transports the vaporized gas. It is characterized by comprising a gas conveying means and a holding/heating means for holding and heating the base material.

Furthermore, in the thin film forming method of the present invention, in the above apparatus, the liquid vaporized by ultrasonic waves contains a metal organic compound,
The formed thin film is characterized in that it is a metal oxide thin film corresponding to the organic compound.

[Function] In the present invention, when the metal-organic compound reaches the surface of the base material, the organic solvent-free form or the precursor adsorbed on the base material surface quickly separates from the organic solvent, so the volume due to firing is reduced. Furthermore, since the metal-organic compound reaches the substrate surface in a gaseous state, the film-forming components are prevented from becoming huge particles before firing, resulting in a thin film that is free of cracks and voids. can be formed.

[Example] FIG. 1 shows a schematic configuration of a thin film forming apparatus of the present invention. In Fig. 1, 1 is an ultrasonic vibrator, 2 is a solution containing a metal-organic compound, 3 and 4 are carrier gas inlets, 5 is a heater for heating the gas during gas transfer, and 6 is a lamp heater. .

Reference numeral 7 represents a substrate holder, which may have a built-in heater for heating the substrate. Reference numeral 8 indicates a base material, and reference numeral 9 indicates a pump exhaust port, and depending on the conditions, the pressure inside the reactor may be reduced to approximately 100 Torr. The lamp heater 6 may be a normal furnace,
Alternatively, the base material may be heated by a CO□ gas laser.

An example of forming a thin film using the above-mentioned apparatus is shown below.

First, silicon tetraethoxide Si (QC2H5)
Ethanol was added to 4, and a nitric acid aqueous solution (pH < 5) diluted with ethanol was added, and the mixture was stirred at room temperature for a period of time to perform partial hydrolysis, and further diluted with water and ethanol to obtain a precursor.

This precursor (ie, solution 2 containing a metal-organic compound) was transferred into the apparatus, vaporized by ultrasonic waves (0.8 MHz to 2 MHz above the cavitation generation region), and introduced into the reactor with carrier gas N2. The precursor is decomposed by heating with the heater 5 to a bleed temperature of 80°C and instantaneously repeating heating and cooling (ON, 0FF) with the lamp heater 6, resulting in a crack-free and void-free SiO□ on the surface of the base material 8. A thin film could be formed.

The film thickness at this time depends on the ON/OFF cycle of the lamp heater 6, and can be controlled within a range of approximately 5 nm to 5 μm.

In addition, the properties of the obtained film are that the refractive index is 1.42, buffered hydrofluoric acid (hydrofluoric acid + ammonium fluoride aqueous solution)
The Elaken rate was 15 people/sec, and it was found to be a high quality SiO□.

[Effects of the Invention] As is clear from the above description, according to the present invention, a high-quality thin film without cracks or voids can be formed on the surface of a base material.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the thin film forming apparatus of the present invention, and Figure 2 (
a), (b) are cross-sectional views showing the steps of the conventional thin film forming method;
FIGS. 3(a), 3(b), and 3(c) are enlarged explanatory diagrams showing the particle morphology of the wet gel used in the conventional method. DESCRIPTION OF SYMBOLS 1... Ultrasonic vibrator, 2... Solution containing a metal organic compound, 3, 4... Carrier gas inlet, 5... Heater, 6... Lamp heater, 7... Base material Holder, 8...Base material, 9...Pump exhaust port, 11...
Base material, 12...Crack, 13...Void, 21.
...Crystal particles, 21...Primary particles, 23...Agglomerated particles. Applicant Rico Co., Ltd. - Figure 1 (a) Figure 2 〇--21 (a) (b) (C) Figure 3 Procedural amendment 1. Display of the case 1990 Patent Application No. 29g13IQ No. 2, Name of the invention Thin film forming device and thin film forming method 3, Person making the amendment Relationship to the case / Patent applicant address 1-3-6 Nakamagome, Ota-ku, Tokyo Issue name (
674) Ricoh Co., Ltd. Voluntary Issue 5, Subject of Amendment 6, Contents of Amendment (1) "Kiyoo Sakuhana" on page 2, line 14 of the specification tube is corrected to "Maio Sakuhana."

Claims (2)

[Claims] (1) A vaporizing means that vaporizes a liquid using ultrasonic waves, a gas introduction means that introduces a carrier gas, a gas transporting means that transports the vaporized gas using the carrier gas, and a holding and heating means that holds and heats the base material. A thin film forming apparatus characterized by being equipped with a heating means. (2) In the apparatus according to claim 1, the liquid vaporized by ultrasonic waves contains a metal organic compound, and the thin film formed is a metal oxide thin film corresponding to the organic compound. Formation method.