JPH01294506A - Production of metallic oxide and thin film thereof with excimer laser - Google Patents

Abstract

PURPOSE:To enable production of high-purity metal oxide and a thin film thereof under mild conditions by irradiating a metal salt of an organic acid or organometallic compound with excimer laser in oxygen atmosphere. CONSTITUTION:A metal salt of an organic acid or organometallic compound expressed by the formula MmRn (M is group IVb element of Si, Ge, Sn or Pb; group VIa element of Cr, Mo or W; R is alkyl group, such as methyl, ethyl, propyl or butyl, or carboxyl group, such as acetoxy, propanoyloxy, butyryloxy or valeroyloxy, or carbonyl, m and n are integers) is dissolved in a soluble solvent or, in the case of a liquid, it is directly dispersed, applied to a substrate and irradiated with excimer laser (optimally KrF laser) in oxygen atmosphere to afford the aimed metal oxide or a thin film thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing metal oxides and metal oxide thin films using an excimer laser.

Background Art Metal oxides and their thin films are used in a variety of fields, particularly in recent years in fine ceramics and recent oxide high-temperature superconducting conductors, which have been used to improve the purity and functionality of the materials themselves. Due to the miniaturization, its applications are rapidly expanding.

The method for producing metal oxides is largely due to technological improvements such as improvements in synthesis technology and chemical reaction purification technology, as well as advances in oxidation technology using heat treatment, such as heating devices and heating methods. However, the generation of metal oxides requires a large amount of thermal energy during the sintering process, and it is therefore extremely difficult to accurately control the composition of the oxides.

On the other hand, metal oxide thin films are used in various fields of electronics, typified by semiconductors, and their manufacturing methods are largely dependent on dry process techniques such as CVD. However, in the CVD method, the reaction temperature is high and the by-product of toxic gas cannot be avoided. There are other methods for producing thin films, such as vacuum evaporation and sputtering, but these methods require high vacuum and high voltage, and are difficult to handle with substances that are difficult to vaporize.

Problems to be Solved by the Invention As the purification of metal oxides progresses, chemical and thermal treatments become more complicated, the number of treatments increases, and the treatment cost becomes expensive. On the other hand, there are limits to achieving high purity, and in particular, the delicate control of the crystal structure of various metal oxides requires very strict processing, resulting in many problems in the manufacturing process. In addition, when manufacturing metal oxide thin films using the dry process described above, CV
The control of processing equipment such as D equipment is delicate, and many voids and cracks are likely to be generated in the thin film, making it technically difficult to produce a high-quality thin film. Continuous processing using this method is also being considered, but at present, sufficient results have not been obtained. In addition, a method of electrochemically producing metal oxides has been considered, but it is theoretically difficult to produce metal oxides other than valve metals such as aluminum.

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors of the present invention have repeated their creative efforts, and as a result, they have discovered the following metal oxide and method for producing the thin film.

That is, in producing a metal oxide, the present invention uses a metal organic salt or an organic metal compound M, R.

(However, M = Si, Gex Sn, 4b of Pb
Group elements, Cr %Mo, W group 6a elements, Mn,, T
C% Re group 7a element: R=CH,,C211C,
H, an alkyl group such as C4H9, or CH3CO
O-, CJsCOO-, C31bCOO-, C4H9C
Production of metal oxides and metal oxide thin films by excimer laser, characterized by irradiating carboxyl groups such as OO- or carbonyl groups of CO (1.7 is an integer) with excimer laser in an oxygen atmosphere. Method. Also,
A metal oxide characterized by dissolving the metal organic salt or organometallic compound in a soluble solvent, or dispersing the solution as it is on a substrate, and then irradiating it with an excimer laser in an oxygen atmosphere. In addition, we focused on lasers, especially excimer lasers, which have been rapidly progressing in recent years, in the production method of metal oxide thin films, and effectively utilize the high intensity of laser light to produce metal organic salts or organometallic compounds in an oxygen atmosphere. The metal oxide and the thin film are produced by photo-oxidation reaction. More specifically, a metal organic salt or an organometallic compound is irradiated with an excimer laser, and the excitation energy decomposes the compound, at the same time activating the metal, and the oxygen in the gas phase, which is also excited and activated, quickly decomposes the compound. It causes an oxidation reaction. Types of excimer lasers include ArF (193nm), KrF (248nm),
XeC1 (308na+), XeF (351rv+)
can be easily used, but short wavelength lasers are advantageous in order to cause this reaction to occur efficiently. but,
Considering operability and gas life, preferably KrF laser irradiation is optimal. For example, when lead acetate is used as the metal organic salt, the reaction proceeds according to the following formula. The reaction proceeds with oxygen in the atmosphere, but when the laser output is strong, oxygen becomes insufficient, so it is necessary to supply oxygen to the reaction site. Since the progress of the reaction is proportional to the amount of oxygen supplied, the reaction is preferably carried out under an oxygen atmosphere.

h ν Pb (C8:IC0O) z → PbO□+CO
7↑ +11□0↑ Under mild conditions, oxides are formed instantly, but since the reaction only progresses in the area that is irradiated with the laser, it is necessary to irradiate it evenly by stirring or the like.

Next, in the case of forming a thin film, the metal organic salt or organometallic compound is dissolved in a soluble solvent such as water, and after being dispersed and coated on the substrate E by spraying or the like, laser irradiation is performed.

In this case, the degree of solution of the metal organic salt is determined by the thickness of the thin film to be formed, so generally, the thinner the thin film is, the better it is to use a dilute solution. Furthermore, since the efficiency of the oxidation reaction may vary depending on the solvent, it is necessary to select the type of solvent depending on the type of metal organic salt. Various types of water, methanol, ethanol, ethylene glycol, glycerin, and mixed solvents thereof were used as the T-container, and as a result, oxides were produced well when water or a mixed solvent of water and methanol was used. The optimal number of repeated pulses for laser irradiation is about 1011z. Furthermore, by moving the substrate, a continuous thin film formation process is possible. Although the reaction proceeds at room temperature, the oxidation reaction proceeds more efficiently when the substrate is heated to about 100°C.

Function The basic reaction of the present invention is as shown above, and its principle is to irradiate the metal with a wavelength having an energy higher than the binding energy of the metal organic salt or organic metal compound, dissociate the bond, and transform the metal into a radical state. It recombines elements with oxygen to produce oxides, but the excimer laser used here not only dissociates bonds, but also
This is because by creating a high-temperature plasma state on the substrate surface, surface annealing becomes possible at the same time.

(Oxidation Annealing) The selection of wavelength is determined by the combination of rare gas and halogen gas that generate the laser.

Typical excimer laser gases and wavelengths currently used are ArF (193nm), KrF (248nm), and KrF (248nm).
m), XeC1 (308 nm), XeF (351 nm)
), but short wavelengths are more advantageous for oxidative annealing. However, as mentioned above, ArF (1
Since KrF (248 nm) irradiation is particularly effective in practice, KrF (248 nm) irradiation is particularly effective. Also, XeC1 (308 nm) has the highest gas stability.
Lasers are also preferably used.

By effectively utilizing the high intensity and high density of excimer laser photons, it is possible to form a uniform thin film not only on a uniformly clean surface but also on a porous substrate regardless of the shape of the substrate surface. This feature is expected to find many uses in electronic materials. Furthermore, since the thickness of the formed oxide thin film can be adjusted by changing the number of pulse repetitions, it is an effective means for controlling the film thickness. It can also be focused to provide a pattern of oxide films with high resolution on the substrate.

Example The present invention will be described below with reference to specific examples.

(Example 1) 40 mg of commercially available reagent grade lead acetate was placed in a reaction vessel equipped with an agate stirrer, stirred, and then heated with a KrF (248 nm) excimer laser for 20 mg without supplying excess oxygen gas.
Irradiation was performed at 0 mJ/pulse-, 1011z for 180 seconds. The generation of 100% pbo was confirmed by analyzing the generated black reaction product by xps, x-ray analysis, and ESCA.

(Example 2) Lead acetate used in Example 1 was saturatedly dissolved in pure water, sprayed onto an alumina substrate, and irradiated with an excimer laser under the above conditions while supplying oxygen gas. The production of 100% pbo was confirmed by analyzing the produced thin film using xps, xvA analysis, and ESCA. xps
The results are shown in Figure 2.

Since peaks due to 4f5/2 and '1/2 of PbO□ appeared, and peaks due to AI of the substrate disappeared, it is clear that the entire surface was covered with a lead oxide thin film.

In addition, although the above-mentioned example described lead acetate as a metal organic salt, a metal organic salt or an organic metal compound Mffit? .

M = Sis G8% Sn, Pb group 4b element, Crs Mo, W group 6a element, Mn5TC% R
Group 7a element of e: R=C1h, C, H,, C2I+?
, an alkyl group such as Ca If q, or CH
3COO-, CzHsCOO-, C3H? COO-,C
4)1. Carboxyl group such as COO-, or CO
A similar effect can be obtained with the carbonyl group of .

Effects of the Invention As described above, the metal oxide and thin film produced according to the present invention have extremely high purity, and by using an excimer laser, the oxide film can be produced under mild conditions and in a short time. Compared to conventional methods, this method significantly saves energy, improves productivity, and reduces process costs, and has great industrial and practical value.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the production equipment for metal oxides and metal oxide thin films using excimer laser, and Fig. 2 is the binding energy (Eb (100 eV/div)) measured by XPS.
In the strength (%) characteristic diagram, a shows the aluminum substrate before reaction, b shows the state after oxidation annealing, and C shows an enlarged view of the lead oxide part. Patent applicant Nichicon Corporation

Claims (2)

[Claims] (1) When producing a metal oxide, a metal organic salt or an organometallic compound M_mR_n (where M=Si, G
Group 4b elements such as e, Sn, and Pb, Group 6a elements such as Cr, Mo, and W, Group 7a elements such as Mn, Tc, and Re: R=CH_3,
Alkyl groups such as C_2H_5, C_3H_7, C_4H_9, or CH_3COO^-C_2H_5CO
O^-, C_3H_7COO^-, C_4H_9COO
Metal oxides and metal oxide thin films produced by excimer laser, characterized by irradiating the carboxyl group of Cal such as ^- or the carbonyl group of CO (m and n are integers) with excimer laser in an oxygen atmosphere. manufacturing method. (2) The metal organic salt or organometallic compound is dissolved in a soluble solvent, or in the case of a liquid solution, the solution is dispersed and coated on a substrate, and then irradiated with an excimer laser in an oxygen atmosphere. Claim No. 1
A method for producing metal oxides and metal oxide thin films using an excimer laser as described in 1.