JPH0578197A - Production of tio2-sno2 film - Google Patents

Abstract

PURPOSE:To enable production of a TiO2-SnO2 solid solution film remarkably excellent in crystallinity at a high speed at a low temperature and to further improve the crystallinity by heat treatment. CONSTITUTION:Oxygen is supplied to a film formation area on a substrate while forming a TiO2-SnO2 film on the surface of a prescribed substrate 2 by vaporizing a vaporization substance from a vacuum-deposition source 1 composed of TiO2 and SnO2 so as to form a TiO2-SnO2 solid solution film. The resultant solid solution film is subsequently subjected to rearrangement of crystal by heating in an oxidative atmosphere at >=1350 deg.C and then to spinodal decomposition by heating in an oxidative atmosphere at >=800 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a film composed of TiO ₂ and SnO ₂ , and more specifically to TiO 2.
₂ or SnO ₂ solid solution film or TiO ₂ —S
The present invention relates to a novel method for producing an nO ₂ spinodal decomposed film.

[0002]

_2. Description of the Related Art Conventionally, TiO ₂ —SnO ₂ based oxide has been attracting attention as a material having functionality by adjusting its composition ratio and stoichiometric composition ratio.
Attempts have been made to further improve the functionality by subjecting the TiO ₂ —SnO ₂ based oxide to spinodal decomposition to form a fine structure.

Conventionally, a TiO ₂ —SnO ₂ type oxide solid solution and a substance obtained by spinodal decomposition have been produced by, for example, a sol-gel method. This method uses Ti and Sn
Alkoxide of metal is mixed in a solvent, applied to a predetermined substrate, dried, baked in an oxidizing atmosphere at 500 to 1000 ° C., and then heat-treated in an oxidizing atmosphere at 1400 ° C. or higher to form TiO ₂ And SnO ₂ are solid-dissolved, and in order to perform spinodal decomposition, this solid solution is heat-treated in an oxidizing atmosphere at 800 ° C. or higher.

[0004]

However, according to the above-mentioned sol-gel method, there is a problem that the film itself becomes porous due to the thermal decomposition of organic substances, and it is difficult to obtain a dense and smooth film. Moreover, there are many setting conditions such as the baking temperature and the baking atmosphere, and it is difficult to control them, and when a dense solid solution film is to be obtained, 100 cycles can be obtained in one cycle.
Since it occurs only at an extremely thin film level of about 0Å, it is necessary to repeat the above-mentioned application, drying, and baking on a predetermined substrate in order to create a thick film. There is a risk of inclusion of impurities.

Therefore, according to the present invention, TiO having excellent crystallinity is used.
_2- SnO ₂ solid solution and spinodal decomposed TiO
_{The present} invention provides a new method capable of forming a _2- SnO ₂ film.

[0006]

[Means for Solving the Problems] The inventors of the present invention have repeatedly studied the above problems, and as a result, as a film forming means, PV has been used.
When forming a film using the D method (physical vapor phase synthesis method),
For example, oxygen gas is blown to the film formation region on the surface of the substrate on which the film is to be formed, and sufficient oxygen is supplied, so that TiO ₂ —Sn
It was found that a film in which O ₂ was uniformly dissolved was formed.
Furthermore, the present inventors have shown that the crystallinity of the solid solution film is dramatically improved by heat-treating the solid solution film at a predetermined temperature, and further, the heat treatment using the solid solution film is stable. It was discovered that spinodal decomposition occurs.

Namely, preparation of TiO ₂ -SnO ₂ film of the present invention, is evaporated from the deposition material evaporation source consisting of TiO ₂ and SnO _2, TiO ₂ -SnO ₂ to a predetermined surface of the substrate
A TiO ₂ —SnO ₂ solid solution film is formed by supplying oxygen to the film formation region of the substrate at the same time as forming the film, and further, the solid solution film is formed in an oxidizing atmosphere. It is characterized in that the crystals are rearranged by heating at 1350 ° C. or higher. Further, according to the present invention, after the solid solution film obtained in the film forming step is rearranged in the crystal, if desired, in a oxidizing atmosphere,
It is characterized in that it is heated at ℃ or more to cause spinodal decomposition.

The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram for explaining a film forming method according to the present invention. In FIG. 1, 1 is a vapor deposition source and 2 is a substrate. According to the present invention, as the vapor deposition source 1, TiO _{2 is used.}
And a bulk body of SnO ₂ is used. Specifically, the TiO ₂ powder and the SnO ₂ powder are mixed and molded and fired in an oxidizing atmosphere at about 700 ° C., and the density thereof is about 50 to 90%. Further, the composition of each oxide of the vapor deposition source 1 can be controlled to a desired ratio according to the function of the film to be formed, but in the case of finally causing spinodal decomposition, TiO ₂ : SnO ₂ is substantially contained. 3:
It is preferably 7 to 7: 3.

Next, from the evaporation source 1, TiO ₂ and Sn
O ₂ is evaporated, and the evaporation source 1 is used as an evaporation means by using an appropriate heating means (not shown) at 1700 to 2000 ° C.
The vapor of the oxide can be generated by heating the vapor deposition material, but it is desirable that the vapor deposition material is sputtered by irradiating the vapor deposition source 1 with argon ions, for example, by the ion beam 3. In addition, a normal vacuum vapor deposition method, a sputtering method, an ion plating method or the like can be adopted.

The vapor deposition material generated from the vapor deposition source 1 is the substrate 2
A film of TiO ₂ —SnO ₂ is formed on the surface of the substrate. According to the present invention, it is important to supply oxygen to the film forming region of the substrate by an appropriate oxygen supply means 5. The main purpose of this is to prevent oxygen deficiency of TiO ₂ and SnO ₂ itself at the time of film formation, and by supplying oxygen, a film in which TiO ₂ and SnO ₂ are homogeneously solid-dissolved is formed. can do. That is, if the film formation is performed without supplying oxygen, the oxygen of SnO _{2 in} the components is dissociated and the film having the target stoichiometric composition cannot be obtained. As the oxygen supply means 5, as shown in FIG. 1, oxygen gas may be supplied to the substrate at a flow rate of about 2 to 10 sccm.

It is desirable that the substrate 2 at this time is heated to a predetermined temperature by an appropriate heating means. This imparts energy when the vapor deposition material is arranged on the surface of the substrate. For example, when heating is performed using the heater 4, the substrate temperature is 300 ° C. or higher, particularly 500.
It is set in the range of ˜700 ° C. This is because the substrate temperature is 3
If the temperature is lower than 00 ° C., an amorphous film is likely to be formed, so that a solid solution is not formed even if the heat treatment is performed, and if the substrate temperature exceeds 700 ° C., SnO ₂ evaporates violently and Ti:
This is because it is difficult to control the Sn ratio.

As a method for applying energy during such film formation, in addition to heating means such as a heater, FIG.
It is also possible to irradiate the film forming region of the substrate with the ion beam 6 as shown in FIG. According to this method, a heating method is not required and a film can be formed by a low temperature process, which is particularly effective. Specifically, 100 to 300 eV,
150 μA / cm ² or more, especially 200 to 300 μA / c
Irradiation may be performed under the condition of m ² . Ion is 150μA / c
This is because if it is lower than m ^2, the film tends to be amorphous like the above, and if it exceeds 300 μA / cm ² , the film itself is sputtered and it becomes difficult to control the film.

In particular, according to the present invention, as shown in FIG. 6, by irradiating an ion beam of oxygen diluted with argon or the like, it is possible to simultaneously supply oxygen and energy during film formation. Especially effective for.

As the substrate used in the above film formation, there is no reaction with the film components by heating at 1400 ° C., or the reaction speed is slow even if they react, and the film is formed of TiO ₂ —SnO ₂ desirable from the viewpoint substrate crystalline film having a specific crystal plane substantially the same lattice arrangement of the membrane, specifically, a sapphire (011 - ²⁾ R face,
(112 ^- 0) is desirably an A plane and (0001) C plane. Further, as another condition, the pressure in the reaction furnace is appropriately set to 1.0 × 10 ^{−5 to} 2.0 × 10 ⁻⁴ torr.

Next, according to the present invention, the TiO ₂ —SnO ₂ solid solution film obtained by the above-mentioned method is added with 135
The heat treatment is performed in an oxidizing atmosphere at 0 ° C. or higher, particularly 1400 to 1500 ° C. According to this heat treatment, the crystals can be rearranged, and the crystallinity of the film can be enhanced by the rearrangement of the crystals as is clear from the comparison of FIG. Further, according to this heat treatment, a sapphire as a substrate as is clear from examples described later - in the case of using the R-plane of (011 ^2), the solid solution film is confirmed that the epitaxially grown on the substrate It In addition, normally, TiO ₂
In this heat treatment for easily reacting with Al ₂ O ₃ at about 1200 ° C., it is important to rearrange the crystals while suppressing the reaction of TiO _{2 with} the sapphire substrate. It is necessary to perform the heat treatment in the range as short as 10 seconds to 5 minutes.

Further, according to the present invention, the TiO ₂ --SnO ₂ solid solution film obtained by the above method has a thickness of 80%.
5 minutes to 1 in an oxidizing atmosphere such as the atmosphere of 0 to 1200 ° C
By heat treatment for 00 hours, spinodal decomposition of the solid solution film can be caused. The temperature of this heat treatment is 8
When the temperature is lower than 00 ° C, spinodal decomposition does not substantially occur,
On the contrary, if the temperature is higher than 1200 ° C, the film undergoes a solid phase reaction with the substrate, which is not desirable.

[0018]

According to the present invention, the vapor deposition source consisting of TiO ₂ and SnO ₂ is used to supply oxygen to the film formation region of the substrate by physical vapor deposition to supply TiO ₂ to the film formation region.
_{A 2-} SnO ₂ solid solution film can be prepared. Moreover, by heating such a film at a predetermined temperature for a short time, rearrangement of the solid solution film occurs, and it is possible to perform epitaxial growth on the substrate by selecting an appropriate substrate. Further, when such solid solution is used to perform appropriate heat treatment to cause spinol decomposition, a TiO ₂ —SnO ₂ film having a homogeneous and stable microstructure can be formed.

[0019]

【Example】

Example 1 As the target 1, a sintered body having a composition of 1: 1 TiO ₂ : SnO ₂ and a density of 4.0 g / cm ³ was prepared. This target was placed in a reaction furnace as shown in FIG. 1 and the substrate 2 was 25 mm × 25 mm × 0.3 mm.
The sapphire substrate (R surface) having the size of 1 was placed at the position shown in FIG. 1, and the pressure in the furnace was set to 5 × 10 ⁻⁵ torr.
Then, the target was irradiated with argon ions and sputtered from the target. On the other hand, the heater 4 is set on the back surface of the substrate 1 with respect to the substrate 1, and the substrate is set to 200 to 700.
Heated to the range of ° C. Further, oxygen was supplied at a flow rate of 5 sccm by directing the nozzle toward the film formation region of the substrate. When film formation was performed for 3 hours in this state, a film of 3000 Å was formed.

The obtained film was subjected to CuKα-X-ray diffraction measurement. The results are shown in Fig. 1. According to FIG. 1, TiO ₂ —SnO ₂ (10
No peak was observed on the 1) plane, and no solid solution was formed. However, by setting the substrate temperature to 300 ° C. or higher and increasing the temperature, the TiO ₂ —SnO ₂ (101) plane peak increased, and the film It was found that itself was oriented in the (101) plane direction.

On the other hand, as a comparison, among the above conditions, film formation was performed without supplying oxygen at all, and a film of 3000 Å was obtained. When this film was observed with an electron microscope, it was a porous film with a rough surface. So XP for this film
The results of measuring S (X-ray photoelectron spectroscopy) are shown in FIGS. 2 and 3. As a result, Sn metal and SnO, which are thought to be due to the reducing action during film formation, were observed in the film, and it was found that oxygen was deficient in the stoichiometric ratio. Therefore, in order to supply oxygen to this film, 1
When heat treatment was performed for an hour, crystal grain growth was observed.
Further, when X-ray diffraction measurement was performed on this film, T
No iO ₂ —SnO ₂ (101) plane peak was observed, and no solid solution was formed.

Next, the solid solution film obtained by the method of the present invention was held in the atmosphere at 1450 ° C. for 1 minute and gradually cooled to room temperature. The treated film was subjected to X-ray diffraction measurement, and the chart was compared with that of the untreated film. The result is shown in FIG. According to FIG. 5, while small ripples were observed at the peak and ground of the chart before the treatment,
Ripple disappears by applying heat treatment,
It is understood that the peak is sharp and the crystallinity of the film is improved. When the electron beam diffraction was measured on the processed film, a spot pattern was observed, and it was found that the film was single crystallized. Sapphire R
Face (011 - ²⁾ and were examined grid array of (101) plane of the solid solution film, both the grating sequence confirmed to be substantially become the same, thereby solid solution film with respect to the sapphire substrate It was confirmed that epitaxial growth was performed.

Next, the solid solution film obtained as described above is heat-treated in the atmosphere at 900 ° C. for 5 to 60 minutes, and X-ray diffraction measurement is performed on the film obtained at each time. went. The results are shown in FIGS. 6 and 7. According to FIGS. 6 and 7, as the heat treatment time is increased, the peak of the solid solution film is the (101) plane peak, and the peak of (20) plane.
2) As the surface peaks gradually decreased, satellite peaks of titanium-rich phase and satellite peaks of tin-rich phase appeared on both sides of these peaks. This phenomenon indicates the occurrence of typical spinodal decomposition. By the way, when the structure was observed with an electron microscope, it was about 10
The lamella-like structure was observed at intervals of nm, and when each tissue was analyzed by EDS (energy dispersive X-ray analysis), the white portion was rich in Ti composition and the black portion was rich in Sn. I found that.

Example 2 As the target 1, a sintered body having a composition of TiO ₂ : SnO ₂ of 1: 1 and a density of 4.0 g / cm ³ was prepared. This target was placed in a reaction furnace as shown in FIG. 8 and the substrate 2 was 25 mm × 25 mm × 0.3 mm.
The sapphire substrate (R surface) having the size of 5 was arranged at the position shown in FIG. 8, and the pressure in the furnace was set to 5 × 10 ⁻⁵ torr.
Then, the target was irradiated with argon ions and sputtered from the target. On the other hand, FIG.
As shown in FIG. 5, the oxygen ion beam diluted with argon is irradiated, and the energy value is 100 to 300 eV.
0μA / cm ^2, it was 250μA / cm ^2. When film formation was performed for 3 hours in this state, a film of 3000 Å was formed.

CuKα-X-ray diffraction measurement was performed on the obtained film. The results are shown in Fig. 9. As is clear from FIG. 9, a TiO ₂ —SnO ₂ (101) plane peak was observed, and it was found that the film itself was oriented in the (101) plane direction.

The obtained film was held in the atmosphere at 1450 ° C. for 1 minute and gradually cooled to room temperature. Then 900 ° C
Heat treatment was performed for 60 minutes in the atmosphere. When an X-ray diffraction measurement was performed on the obtained film, a satellite peak of a titanium-rich phase and a satellite peak of a tin-rich phase were observed as in Example 1, and it was confirmed that spinodal decomposition occurred.

[0027]

As described above in detail, according to the method of the present invention, a solid solution of TiO ₂ —SnO ₂ having a very high crystallinity at a low temperature and a high speed film formation as compared with the conventional sol-gel method or the like. A film can be formed and its crystallinity can be further enhanced by heat treatment. Further, by heat-treating the solid solution film having high crystallinity, spinodal decomposition can be stably generated and a homogeneous structure can be generated.

As a result, the microstructure utilizing spinodal decomposition can be put to practical use as a sensor element or other functional oxide film.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram of an apparatus for producing a TiO ₂ —SnO ₂ film of the present invention.

FIG. 2 TiO ₂ —SnO obtained by the method of the present invention
It is a figure which shows the change of the X-ray diffraction chart with respect to the substrate temperature of ₂ films.

FIG. 3 is a diagram showing an X-ray photoelectron spectroscopy analysis chart (440 to 470 eV) of a TiO ₂ —SnO ₂ film obtained by a comparison method.

FIG. 4 is a view showing an X-ray photoelectron spectroscopy analysis chart (470 to 500 eV) of a TiO ₂ —SnO ₂ film obtained by a comparison method.

FIG. 5 is a diagram showing X-ray diffraction charts of a film after a film forming process and a film after a heat treatment.

FIG. 6 is a diagram showing changes in an X-ray diffraction chart (2θ = 30 to 40 °) with respect to heat treatment time of a film in a spinodal decomposition step.

FIG. 7 is a diagram showing changes in the X-ray diffraction chart (2θ = 70 to 80 °) with respect to the heat treatment time of the film in the spinodal decomposition step.

FIG. 8 is a schematic layout diagram showing another embodiment of the apparatus for producing a TiO ₂ —SnO ₂ film of the present invention.

FIG. 9: TiO ₂ —SnO ₂ obtained in Example ₂
It is an X-ray-diffraction chart figure of a film.

[Explanation of symbols]

 1 evaporation source 2 substrate 3 ion beam 4 heater 5 oxygen supply means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01B 13/00 503 B 7244-5G

Claims (4)

[Claims] 1. A vapor deposition material consisting of TiO ₂ and SnO ₂ is vaporized to vaporize a vapor deposition material, and TiO ₂ --S is deposited on a predetermined substrate surface.
simultaneously forming the nO ₂ film, TiO ₂ -S, characterized in that to produce a film made of a solid solution of TiO ₂ and SnO ₂ by supplying oxygen to the film formation region of the substrate
Manufacturing method of nO ₂ film. 2. A vapor deposition material composed of TiO ₂ and SnO ₂ is vaporized to vaporize a vapor deposition material, and TiO ₂ --S is deposited on a predetermined substrate surface.
At the same time as forming the nO ₂ film, oxygen is supplied to the film formation region of the substrate to form a film made of a solid solution of TiO ₂ and SnO _2, and then the solid solution film is further formed on the substrate.
A method for producing a TiO ₂ —SnO ₂ film, which comprises performing a heat treatment in an oxidizing atmosphere at 0 ° C. or higher. 3. A vapor deposition material composed of TiO ₂ and SnO ₂ is vaporized to vaporize a vapor deposition material, and TiO ₂ --S is deposited on a predetermined substrate surface.
A film forming step of forming a film of a solid solution of TiO ₂ and SnO ₂ by supplying oxygen to the film forming region of the substrate at the same time as forming the nO ₂ film, and the solid solution film in an oxidizing atmosphere. A method of producing a TiO ₂ —SnO ₂ film, comprising a decomposition step of heating at 800 ° C. or higher to decompose spinodal. 4. A vapor deposition material composed of TiO ₂ and SnO ₂ is vaporized to vaporize a vapor deposition material, and TiO ₂ --S is deposited on a predetermined substrate surface.
A step of forming a film of a solid solution of TiO ₂ and SnO ₂ by supplying oxygen to the film formation region of the substrate at the same time as forming the nO ₂ film, and forming the solid solution film at 1350 ° C. or higher. A method of manufacturing a TiO ₂ —SnO ₂ film, comprising: a step of heat treatment at a temperature; and a step of heating the solid solution film after the heat treatment at 800 ° C. or higher in an oxidizing atmosphere to cause spinodal decomposition.