JP4076799B2 - Film formation method and apparatus for photocatalyst TiOx - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a TiOx (x <2) film forming method and apparatus therefor, and more particularly to sputtering a rare gas cation that has been converted into a plasma on a target, and a substrate disposed oppositely in a vacuum chamber. The present invention relates to a TiOx (x <2) film forming method and apparatus for forming a TiOx (x <2) film.
[0002]
[Prior art]
The TiO ₂ film has a photocatalytic function, and exhibits excellent effects such as antibacterial, deodorant, antifouling, and hydrophilicity.
There is a sputtering method as a film forming method for forming a TiO ₂ film. This method is advantageous for uniformly forming a dense TiO ₂ film over a large area, and can provide high adhesion. .
As such a sputtering film forming method, there is a method of forming a film on a glass substrate by O ₂ gas reactive sputtering of a Ti target, but the film forming rate is low.
[0003]
[Problems to be solved by the invention]
The present invention is an object that is made in view of the aforementioned problems Do take advantage by a sputtering method described above is to provide a film forming method and apparatus of high photocatalytic TiOx of RaNaru deposition rate.
[0004]
The above-described problems are caused by disposing a target made of TiOx (x <2) facing the substrate in the vacuum chamber, introducing only a rare gas into the vacuum chamber, and sputtering the target by converting the rare gas into plasma. a method of forming a photocatalyst TiOx forming a TiOx film (x <2) on the substrate, the target substantially parallel to generate a magnetic flux on the surface of, the substrate was heated temperature from 0.99 ° C. to 240 ° C., The plasmatization is solved by a film formation method of the photocatalyst TiOx, which is performed by superimposing a DC voltage and an AC voltage.
[0005]
Alternatively, a target made of TiOx (x <2) disposed opposite to a substrate installed in the vacuum chamber, a gas introduction means for introducing only a rare gas into the vacuum chamber, and the rare gas is converted into plasma. Gas exciting means, magnetic field generating means for generating magnetic flux substantially parallel to the surface of the target, and heating means for heating the substrate from 150 ° C. to 240 ° C., the gas exciting means comprising a DC power supply The photocatalyst TiOx film forming apparatus is characterized in that the rare gas is turned into plasma by superimposing the DC voltage of the DC power supply and the AC voltage of the AC power supply.
With the above configuration, the photocatalyst TiOx (x <2) can be formed on the substrate at a high speed and a low temperature.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Although FIG. 1 is a schematic view of a sputtering apparatus according to the implementation of the embodiment of the present invention, a substrate 2 made of glass TiOx film in the vacuum chamber 1 is formed is provided in FIG., Which is a heater (heating means 3 ) It is set as the structure heated between room temperature and 250 degreeC by 3. FIG. Further, a target 4 made of TiOx (x <2) is disposed facing the lower side (however, via the shutter 7 in FIG. 1). A shutter 7 is rotatably disposed on the column 6 between the substrate 2 and the target 4. The vacuum chamber is evacuated to a vacuum degree of 1 × 10 ⁻⁴ Torr or less by an exhaust system (not shown).
[0007]
In the vacuum chamber 1, argon gas was introduced from the supply source 8 and the total process pressure was set to 5 × 10 ⁻³ Torr. The target 4 according to the present embodiment is made of TiOx, which is a reduced product of TiO ₂ (rutile) powder, and has conductivity. That is, oxygen is released by the atmosphere during the sintering process in which the target 4 is produced by high-temperature sintering of TiO ₂ (rutile) powder. That is, it is reduced. Therefore, it is considered that when the target 4 is reached, TiOx (x <2.0). From the viewpoint of TiO ₂ , x of TiOx is considered to be a numerical value close to 2 that is very slightly shifted toward the smaller side. Basically, it is an N-type semiconductor with oxygen deficiency when viewed from TiO ₂ .
[0008]
As is well known, the target 4 is disposed on a magnet (magnetic field generating means) 5 and generates a magnetron / sputtering magnetic flux substantially parallel to the surface of the target 4. A negative voltage of a DC (direct current) power source 9 as gas excitation means is supplied to the target 4 via an abnormal discharge preventer (Active ArcKiller-abbreviated as A ₂ K) 10 and a low-pass filter 11. Further, an RF (alternating current) voltage of an RF power source 12 as gas excitation means is supplied through a matching box 13. A ₂ K10 prevents abnormal discharge that may occur between the erosion part and the non-erosion part of the target 4. In this case, a positive voltage is applied in pulses to a normal DC power supply. The principle of A ₂ K is that when a positive voltage is applied to the conductive target, electrons in the plasma are drawn into the target and neutralize with the positive charge accumulated in the non-erosion part to prevent abnormal discharge. is there.
[0009]
The sputtering apparatus according to the embodiment of the present invention is configured as described above. Next, this operation and its operation will be described.
[0010]
Although the sputtering apparatus according to the embodiment of the present invention is a so-called batch type, as described above, (DC + RF) superimposed magnetron sputtering is possible. Alternatively, only DC or RF can be used. Further, as described above, after evacuating until the degree of vacuum in the vacuum chamber 1 becomes 1 × 10 ⁻⁴ Torr or less, argon gas is supplied from the supply source 8 into the vacuum chamber 1 to a total process pressure of 5 × 10 ⁻³ Torr. To be introduced. Glass was used as the substrate 2, and the following experiment was performed by heating the substrate temperature between room temperature and 250 ° C. with the heater 3. The substrate temperature was measured by a thermocouple (not shown) attached on the center of the back surface of the substrate 2.
[0011]
As described above, the conductive oxide TiOx (x <2.0) obtained by reducing TiO ₂ (rutile) powder was used as the target 4. The process rare gas was argon introduced from the argon supply source 8 and was introduced so that the process pressure was 5 × 10 ⁻³ Torr. Only argon gas was introduced with the shutter 7 closed. The power ratio between DC and RF was 1:15, DC power was 100 watts, RF power was 1500 watts, and these were superimposed. First, pre-sputtering was performed for 5 minutes with the shutter 7 closed. Then, the shutter 7 was opened, and a TiOx film was formed. The film thickness of the formed TiOx (x <2) film is 5000 mm.
[0012]
FIG. 2 shows an experiment using the apparatus of FIG. 1 for comparing the conventional target with Ti and the target TiOx according to the embodiment of the present invention. In the first experiment, DC magnetron sputtering is performed. When the target is titanium Ti, it is indicated by ●, and in the second experiment, it is indicated by ■ when the target is TiOx by DC magnetron sputtering, and the third experiment is a magnetron in which (DC + RF) is superimposed. When the target is TiOx by sputtering, it is indicated by ▲, and in the fourth experiment, it is indicated by ♦ when the target TiOx is performed by magnetron sputtering only with RF power.
[0013]
As is apparent from the figure, in any of the above experiments, the film formation rate (Å / min) increases almost in proportion to the power watts (W). When DC magnetron sputtering is performed with the same power and the target as TiOx, the power is 2500 watts and is about 1225 Å / min, which is about 5 times the 245 Å / min when the DC magnetron sputtering and the target is titanium Ti. Yes. That is, even with the same discharge type DC magnetron sputtering, the film formation rate is significantly higher when the target is TiOx.
[0014]
Next, as was done in the third and fourth experiments, when the discharge method is the RF (alternating current) voltage method for the TiOx target as well, the same 2500 watt (extrapolated rate is set as shown by ◆). (Estimated) is not much different from the case of targeting titanium Ti. That is, the film formation rate is much higher in the DC discharge method.
[0015]
The (DC + RF) superposed discharge method is indicated by ▲, but at 2500 watts (by extrapolation method), it becomes almost 800 Å / min, which is almost an intermediate value between the DC discharge method and the RF discharge method. .
[0016]
Next, FIG. 3 shows the experimental results of measuring the relationship between the contact angle of water and the substrate temperature using the same apparatus. That is, the contact angle of water was measured 1 hour after irradiation with black light (ultraviolet light) (1 mW / cm ² ). Affinity or contact angle with water decreases with increasing substrate temperature, but the discharge mode of the target as TiOx (DC + RF) Modulation method and then is small the same substrate temperature 200-240 ° C. But most contact angle if. Photocatalytic properties appear at a substrate temperature of about 210 ° C.
[0017]
In the DC discharge method using a TiOx target, the contact angle is slightly smaller than when the target is titanium Ti, but there is a large difference in the region where the substrate temperature is low compared to the case of (DC + RF) superposition.
[0018]
Next, FIG. 4 shows the relationship between the contact angle of water and the substrate temperature with the RF frequency as an auxiliary variable. It is the largest at 13.56 MHz, and then decreases as 27 MHz, 40 MHz, and 60 MHz. As is apparent from the figure, when the substrate temperature is high (about 210 ° C.), it does not change much above 27 MHz. Therefore, it is considered that the frequency of 27 MHz or higher when the substrate temperature is low, and 27 MHz or higher when the substrate temperature is high is optimal for obtaining the contact angle characteristics of water.
[0019]
The effects of the embodiment of the present invention are summarized as follows.
(1) In the conventional Ti target O ₂ reactive sputtering method, since the substrate was heated to 300 ° C. or higher, a film could not be formed on the low melting point substrate. A TiOx film can be formed on a low melting point substrate.
(2) A photocatalytic TiOx film can be formed at a higher speed and a lower temperature by the (DC + RF) superimposed sputtering method.
(3) TiOx can be formed by a simple operation at low cost without using an oxidizing gas.
[0020]
Although the embodiments of the present invention have been described above, the present invention is of course not limited thereto, and various modifications can be made based on the technical idea of the present invention.
[0021]
For example, in the above embodiment, argon is used as a rare gas, but other rare gases such as helium and neon may be used.
[0022]
In the above embodiment, the substrate is made of glass. However, the substrate can be applied to other insulating materials or conductive materials.
[0023]
In the above embodiment, a target obtained by sintering TiO ₂ rutile powder at a high temperature as TiOx (x <2) is used as a target. However, the present invention is not limited to this method. It can be much smaller.
[0024]
For example, naturally occurring Ti ₂ O ₃ falls within the scope of the invention because x is 1.5 and less than 2. Although there is a composition of Ti _n O _(2n-1) (n = 4 to 9), Ti ₄ O ₇ and Ti ₅ O ₉ are metal conductive or semiconductor and are applicable to the present invention. That is, as described in the embodiment, the target is not limited to the TiOx target obtained by high-temperature sintering of rutile powder.
[0025]
【The invention's effect】
According to the film forming method and apparatus of the photocatalyst TiOx of the present invention as mentioned above, it is possible to form a photocatalyst TiOx film at a low temperature and high deposition rate than conventional.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a sputtering apparatus according to a first embodiment of the present invention.
FIG. 2 is a graph showing the relationship between the power and the deposition rate when the target is titanium Ti and TiOx using the same apparatus.
FIG. 3 is a graph showing the relationship between the substrate temperature and the contact angle of water when the discharge method is variously changed and the target is titanium Ti and TiOx.
FIG. 4 is a graph showing the relationship between the substrate temperature and the contact angle of water when the frequency of RF power is changed.
[Explanation of symbols]
1 Vacuum chamber 2 Substrate 4 Target 5 Magnet 8 Argon gas supply source 9 DC power supply 12 RF power supply

Claims (5)

A target made of TiOx (x <2) is disposed facing the substrate in the vacuum chamber, only a rare gas is introduced into the vacuum chamber, and a TiOx film is formed on the substrate by sputtering the target by converting the rare gas into plasma. A method of forming a photocatalytic TiOx to form (x <2),
Said target substantially parallel to generate a magnetic flux on the surface of, the substrate was heated temperature from 0.99 ° C. to 240 ° C., wherein the plasma is formed in the photocatalyst TiOx which is characterized in that the superposition of a DC voltage and an AC voltage Membrane method. The photocatalytic TiOx film forming method according to claim 1, wherein the rare gas is an argon gas. The photocatalyst TiOx film forming method according to claim 1, wherein the substrate temperature is heated from 150 ° C to 210 ° C, and the frequency of the AC voltage is set in a range of 27 MHz to 60 MHz. A target made of TiOx (x <2) disposed opposite to a substrate placed in a vacuum chamber;
Gas introduction means for introducing only a rare gas into the vacuum chamber;
Gas excitation means for converting the rare gas into plasma;
Magnetic field generating means for generating magnetic flux substantially parallel to the surface of the target;
Heating means for heating the substrate from 150 ° C. to 240 ° C.,
Said gas pumping means, and a DC power supply and an AC power source, the deposition of the photocatalytic TiOx, characterized in that a plasma of the rare gas by superimposing a DC voltage and an AC voltage of the AC power supply of the DC power supply apparatus. 5. The photocatalyst TiOx film forming apparatus according to claim 4, wherein the frequency of the AC power source is in a range of 27 MHz to 60 MHz.

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