JP5929673B2 - Titanium oxide vapor deposition material - Google Patents

Description

  The present invention relates to a vapor deposition material mainly composed of titanium oxide.

Vacuum deposition is a technique for forming a deposited film on an object by evaporating a deposition material by an electron gun or resistance heating in a vacuum chamber. Titanium dioxide (TiO ₂ ) vapor-deposited film is formed from a titanate compound-based vapor-deposited material by vacuum vapor deposition, but has a very high refractive index and excellent heat resistance. Yes.

  If an attempt is made to form a titanium dioxide vapor deposition film using titanium dioxide as a vapor deposition material, oxygen gas is released when the vaporized vapor deposition material solidifies to form a film (during vapor deposition film formation), so the quality of the vapor deposition film is not good. Therefore, the vapor deposition material generally takes a form other than titanium dioxide. For example, it takes a form combining some of other titanium oxides and metal titanium.

Alternatively, there is a technique for adding other elements to the vapor deposition material for various purposes. In Patent Document 1, titanium oxide (TiO _A , A = 1. 0 to 1.75) and zirconium oxide are mixed at a predetermined ratio, and a technique for sintering or melting and solidifying has been proposed.

  In Patent Document 2, for a layer formed by vapor deposition, titanium oxide and ytterbium oxide are added at a predetermined molar ratio so that the composition does not change during melting and vapor deposition and the refractive index is 2.0 or more. Techniques have been proposed in which the contained materials are used as vapor deposition materials.

  In Patent Document 3, a technique for doping titanium dioxide with aluminum oxide, zirconium oxide or the like so as to increase the conductivity of a sputtering target made of titanium dioxide and to make the refractive index of a layer deposited by sputtering to be 2.3 or more. Has been proposed.

In Patent Document 4, an oxide from the group consisting of zirconium oxide, hafnium oxide, yttrium oxide and ytterbium oxide is added to TiO _x (x = 1.4) in order to increase the mechanical strength of the titanium oxide-based sintered body deposition material. To 1.8) have been proposed. Specifically, titanium dioxide, titanium metal and zirconium oxide are mixed, granulated, and sintered under reduced pressure.

However, although the technique of Patent Document 4 can improve the mechanical strength to some extent, it has not been able to sufficiently suppress the occurrence of splash during vapor deposition. In view of such circumstances, the applicant of the present invention includes a technique for adding a compound having a garnet structure to a titanium oxide (titanium oxide) represented by a general formula TiO _x (x = 1.4 to 1.8), Or the technique which makes the titanium suboxide contain the multiple types of oxide which made the yttrium oxide essential was proposed, and it applied for earlier (patent document 5).

JP-A-5-264804 JP-T-2006-519305 JP 2003-073820 A JP-A-9-241830 JP 2012-107276 A

  With the technique of Patent Document 5, a titanium oxide-based vapor deposition material having performance equivalent to that of a titanium suboxide vapor deposition material, improved mechanical strength, and capable of suppressing the occurrence of splash during vapor deposition can be obtained. It was. However, in subsequent studies, the present inventors have discovered that when the deposition target is a material such as a resin that cannot increase the substrate temperature, the refractive index of the deposited film obtained can be lower than the assumed value. Depending on the application of the material to be deposited, the required standard for refractive index may be strict, and there is still room for improvement.

  The present invention has been made in view of the above circumstances. An object of the present invention is to provide a titanium dioxide vapor-deposited film having performance equivalent to that of a titanium suboxide vapor deposition material, sufficient mechanical strength, suppression of splash, and a high refractive index regardless of the vapor deposition target. It is providing the titanium oxide type vapor deposition material which can obtain stably.

  The inventors of the present invention have made extensive studies and have completed the present invention. The present inventors have found that a vapor deposition material including a sintered body containing a specific oxide and a titanate in a specific composition of titanium oxide is not easily crushed during handling, and even if crushed, fine powder is hardly present. It has been found that no reduction in refractive index due to vapor deposition conditions can be prevented.

The vapor deposition material of the present invention includes a main component composed of a titanium oxide represented by a composition formula TiO _x (1.4 ≦ x ≦ 1.8) and a group composed of aluminum oxide, zirconium oxide, hafnium oxide, and ytterbium oxide. A first subcomponent consisting of at least one selected, a second subcomponent consisting of at least one selected from the group consisting of a compound having a garnet structure and yttrium oxide, and a third consisting of at least one titanate. It is characterized by being a sintered body comprising the subcomponents of

  The first subcomponent is preferably aluminum oxide.

  In the third subcomponent, the titanate is preferably at least one alkaline earth metal titanate.

  The total of the first subcomponent, the second subcomponent, and the third subcomponent is preferably 1 wt% or more and 10 wt% or less with respect to the sintered body.

The vapor deposition material is preferably a sintered body that is fired at 1300 ° C. to 1750 ° C. under a pressure of 0.1 Pa to 1.0 × 10 ⁻⁴ Pa.

  Since the titanium oxide-based vapor deposition material of the present invention has the above-mentioned characteristics, it maintains the performance of titanium suboxide, mechanical strength, and splash suppression capability, and further has a high refractive index regardless of the vapor deposition target. A titanium vapor deposition film can be obtained stably.

  Hereinafter, the vapor deposition material of the present invention and the manufacturing method thereof will be described. However, the present invention is not limited by the following description.

  The vapor deposition material of this invention contains the sintered compact which consists of a main component and 3 types of subcomponents. Hereinafter, these will be mainly described.

<Main component>
The main component is titanium suboxide represented by the composition formula TiO _x (1.4 ≦ x ≦ 1.8). When titanium suboxide is used as a vapor deposition material and vapor deposition is performed under an appropriate oxygen partial pressure, gas generation during vapor deposition film formation is suppressed, and a high quality vapor deposition film can be obtained. When the vapor deposition material is titanium dioxide, problems such as formation of vacancies in the vapor deposition film occur due to gas generation, resulting in poor quality of the vapor deposition film.

If the value of x is less than 1.4, the vapor deposition film tends to be colored, whereas if it exceeds 1.8, gas generation tends to increase when the vapor deposition film is formed, so 1.4 ≦ x ≦ 1.8. There is a need. It is preferable that 1.5 ≦ x ≦ 1.7 because energy required for vaporizing the vapor deposition material becomes low. It is more preferable that 1.6 ≦ x ≦ 1.7 (corresponding substantially to Ti ₃ O ₅ ) because particularly necessary energy is reduced.

<First subcomponent>
The first subcomponent consists of at least one selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, and ytterbium oxide. These increase the bond strength between particles of the obtained sintered body. As a result, in spite of being a sintered body of titanium suboxide, a problem of easily crushing and generating fine powder is suppressed. In the titanium oxide-based sintered body, aluminum oxide is particularly preferable because of its high effects. However, the first subcomponent promotes particle growth during firing and increases grain boundaries in the sintered body. Since this grain boundary causes the occurrence of splash during vapor deposition, a second subcomponent described later is required.

  If the content of the first subcomponent is too small, the effect does not appear. If the content is too high, the adjustment of other subcomponents is necessary, and is adjusted accordingly. A preferable range is 0.5% by weight or more and 2.0% by weight or less with respect to the sintered body, and it is easy to overcome various problems. A more preferable range is 0.7 wt% or more and 1.5 wt% or less.

<Second subcomponent>
The second subcomponent is at least one selected from the group consisting of a compound having a garnet structure and yttrium oxide. These have the effect of increasing the bond strength between the particles of the obtained sintered body and suppressing the particle growth during firing. Therefore, the presence of the first and second subcomponents can significantly increase the mechanical strength of the obtained sintered body and suppress the occurrence of splash during vapor deposition.

For compounds having a garnet structure, orthosilicate (so-called meteorite) represented by A ₃ B ₂ (SiO ₄ ) ₃ (A is Ca, Fe, Mn, Mg, etc., B is Al, Cr, Ti, etc.) , Rare earth iron garnet represented by yttrium iron garnet (YIG), rare earth aluminum garnet represented by yttrium aluminum garnet (YAG), and the like. Among these, rare earth aluminum garnet is preferable because it is easy to obtain a sintered body having an appropriate strength.

  Among the rare earth aluminum garnets, those in which at least one element selected from the group consisting of yttrium, lanthanum, gadolinium and lutetium is a rare earth element are more preferable because the properties of the sintered body can be easily controlled. Among them, YAG or a rare earth element whose main component is yttrium is particularly preferable because of little manufacturing variation.

  As a simple oxide having the same effect as the compound having the garnet structure described above, there is yttrium oxide. Therefore, a compound having a garnet structure, yttrium oxide, or both can be used.

  Also for the second subcomponent, for the same reason as the first subcomponent, the preferable content range is 0.5 wt% or more and 2.0 wt% or less with respect to the sintered body. More preferably, they are 0.7 weight% or more and 1.5 weight% or less.

<Third subcomponent>
The third subcomponent is composed of at least one titanate. Titanate tends to have a refractive index equal to or higher than that of titanium dioxide, and does not offset the effects of the first and second subcomponents. Therefore, when these are used as the third subcomponent, the high refractive index film can be stably maintained even at a relatively low temperature, and the refractive index lowered by the first subcomponent and the second subcomponent is suppressed. . As titanates, titanates such as alkali metals, alkaline earth metals, and rare earth metals can be selected. Among them, alkaline earth metal titanates suppress splash by coexisting with the second subcomponent. It is preferable because the effect is increased synergistically and the price is low. In particular, it is more preferable that the alkaline earth metal is either barium or strontium, or both because a stable film can be formed.

  If the content of the third subcomponent is too small, the effect cannot be obtained. If the content is too large, the splash suppressing effect is lowered. Since the third subcomponent holds the key for stably forming the high refractive index film, the preferred range is larger than the first and second subcomponents. A preferable range is 1.0% by weight or more and 5.0% by weight or less with respect to the sintered body, and it is easy to overcome various problems. More preferably, it is 1.5 weight% or more and 3.0 weight% or less.

<Ratio of main component and subcomponent>
In the vapor deposition material of the present invention, the main component determines basic characteristics as the vapor deposition material. Therefore, if it is present at approximately 80% by weight or more with respect to the entire vapor deposition material, it is assumed to be a main component. On the other hand, if there are too many subcomponents, the characteristics of the main component may be impaired. If there are too few subcomponents, the effects of the subcomponents will not be manifested. In the present invention, it is preferable that the total of the subcomponents is 1% by weight or more and 10% by weight or less with respect to the sintered body because the problems specific to titanium suboxide can be solved while maintaining the basic characteristics as the vapor deposition material. A more preferable range is 3% by weight or more and 5% by weight or less. In addition, components other than the main component and the subcomponent may be included depending on the purpose or by mixing in a manufacturing process, a vapor deposition process, or the like. However, the range is such that the main component functions as the main component.

<Relationship between subcomponents>
About the 1st subcomponent and the 2nd subcomponent, when the weight ratio is close to 1: 1, since both fine powder generation | occurrence | production and splash generation | occurrence | production can be suppressed effectively, it is preferable. If the ratio is substantially between 1: 0.85 and 1: 1.15, it can be suppressed sufficiently effectively. For the first and second subcomponents and the third subcomponent, in order to stably obtain a high refractive index deposited film, the third subcomponent is added to the total of the first and second subcomponents. More is preferable. If the weight ratio of the two is between about 1: 1.5 and 1: 3.0, the effect is particularly high, and various problems are easily overcome, which is particularly preferable.

<Method for producing vapor deposition material>
Next, the manufacturing method of the vapor deposition material of this invention is demonstrated.

  The vapor deposition material of this invention contains the sintered compact obtained through the process including a mixing process and a baking process. Hereinafter, the method for producing a sintered body will be mainly described.

<Mixing process>
The raw material of the main component and the raw material of the subcomponent are mixed by a known method to obtain a mixed raw material. The mixed raw material may be further subjected to granulation, pressure molding and the like.

  As the main component material, a commercially available main component having the target composition may be used, or metallic titanium and various titanium oxides may be appropriately selected according to the target composition and used in combination. For example, various combinations such as titanium metal and titanium dioxide, titanium monoxide and titanium dioxide, metal titanium and titanium monoxide and trititanium oxide, and dititanium trioxide and titanium dioxide are possible. In consideration of easy availability of raw materials, price, ease of handling, etc., it is preferable to mix titanium metal and titanium dioxide.

  A compound having a target composition is used as a raw material for the accessory component. In order to prevent an unexpected reaction during firing, raw materials in other forms (for example, halides, sulfates, etc.) are not used.

<Baking process>
The mixed raw material obtained in the mixing step is fired to obtain a sintered body. The firing method may be such that the atmosphere in the furnace is adjusted so as not to react with titanium and fired in an electric furnace or the like, or the degree of vacuum in the furnace is increased (exhaust and depressurized) and fired in a vacuum furnace. Good. The latter is preferable because it is a realistic method. In the former case, a rare gas atmosphere such as argon is used.

  The firing temperature is appropriately determined depending on the furnace structure, atmosphere, and the like. If it is too low, the sintering is insufficient, and if it is too high, the sintered body tends to be too stiff or grain growth tends to occur. In the case of atmospheric firing, it may be 1200 ° C to 1500 ° C, and preferably 1300 ° C to 1400 ° C. In the case of vacuum firing, the temperature may be 1300 to 1750 ° C, and preferably 1650 to 1720 ° C. Vacuum firing is more preferable than atmosphere firing because titanium can be almost certainly prevented from reacting with elements other than oxygen.

In the case of vacuum firing, firing as a pressure range of 10 Pa or less makes sense as vacuum firing. If the degree of vacuum is high, the pressure is never high, but considering the cost and labor, a pressure range of 1.0 × 10 ⁻¹ Pa to 1.0 × 10 ⁻⁴ Pa is realistic and preferable.

<Other processes>
The obtained sintered body may be adjusted in particle size by appropriately providing a pulverization step according to the purpose of use. Or you may cut | divide into the fragment | piece of a specific magnitude | size with a high hydraulic-pressure cutting machine etc. The sintered body contained in the vapor deposition material of the present invention hardly causes unintentional crushing during normal handling, and hardly generates fine powder in the pulverization process.

  In the sintered body obtained through these steps, the main component and each subcomponent are present independently. This can be confirmed by powder X-ray diffraction (XRD). That is, the shape of the XRD spectrum is approximately the same as that of the main component. However, the background noise increases, and the peak of the spectrum has a half-width that is slightly broadened. From this, it can be seen that although no change has occurred chemically, a change has occurred in the crystalline characteristics. In addition, since the relative amount is small, the peak of the spectrum related to each subcomponent cannot be clearly observed.

  Hereinafter, it demonstrates more concretely using an Example. Of course, the present invention is not limited to the examples.

  85.3% by weight of titanium dioxide powder having an average particle size of 0.5 μm, 10.2% by weight of titanium metal powder with coarse particles removed by a metal mesh screen having a nominal opening of 45 μm, 2.5% by weight of strontium titanate, A mixed raw material was obtained by mixing 1.0% by weight of aluminum oxide powder and 1.0% by weight of YAG powder with a stirring mixer. The mixed raw material was granulated into granules having a particle size of about 0.5 mm to 3.0 mm with a granulator. The obtained granulated product was fired at 1700 ° C. for 2 hours under a reduced pressure of 1 Pa or less to obtain a sintered body. The obtained sintered body was coarsely pulverized to obtain sintered granules having a particle size of about 0.5 mm to 3.0 mm.

  Sintered granules were obtained in the same manner as in Example 1 except that 85.7% by weight of titanium dioxide powder, 10.3% by weight of titanium metal powder, and 2.0% by weight of strontium titanate were mixed.

  Sintered granules were obtained in the same manner as in Example 2 except that 2.0% by weight of barium titanate was mixed instead of strontium titanate.

[Comparative Example 1]
Titanium dioxide powder with an average particle diameter of 0.5 μm, 86.6% by weight, titanium metal powder with coarse particles removed by a metal screen having a nominal opening of 45 μm, 10.4% by weight, aluminum oxide powder 1.0% by weight and 2.0% by weight of YAG powder was mixed with a stirring mixer and granulated into granules having a particle size of about 0.5 mm to 3.0 mm with a granulator. The obtained granulated product was fired at 1700 ° C. for 2 hours under a reduced pressure of 1 Pa or less to obtain a sintered body. The obtained sintered body was coarsely pulverized to obtain sintered granules having a particle size of about 0.5 mm to 3.0 mm.

[Comparative Example 2]
A mixture of 89.3 wt% titanium dioxide powder having an average particle size of 0.5 μm and 10.7 wt% of metal titanium powder from which coarse particles have been removed by a metal mesh sieve having a nominal aperture of 45 μm is mixed with a stirring mixer. It was granulated into granules having a particle size of about 0.5 mm to 3.0 mm with a granulator. The obtained granulated product was fired at 1700 ° C. for 2 hours under a reduced pressure of 1 Pa or less to obtain a sintered body. The obtained sintered body was coarsely pulverized to obtain sintered granules having a particle size of about 0.5 mm to 3.0 mm.

[Comparative Example 3]
The mixed raw material was granulated in the same manner as in Comparative Example 2. The obtained granulated product was fired at 1800 ° C. for 2 hours under a reduced pressure of 1 Pa or less to obtain a melt. The obtained melt was coarsely pulverized to obtain granules having a particle size of about 0.5 mm to 3.0 mm.

[Comparative Example 4]
86.6% by weight of titanium dioxide powder having an average particle diameter of 0.5 μm, 10.4% by weight of metal titanium powder from which coarse particles have been removed by a metal mesh screen having a nominal opening of 45 μm, and 3.0% by weight of strontium titanate The mixture was mixed with a stirring mixer and granulated into granules having a particle size of about 0.5 to 3.0 mm with a granulator. Thereafter, sintered granules were obtained in the same manner as in Example 1.

<Fine powder generation rate>
The sintered granules of Examples 1 to 3 and Comparative Examples 1 to 4 were packed in a storage nylon bag, moved to a vapor deposition apparatus, then taken out from the storage nylon bag and installed in the vapor deposition apparatus. Fine powder generated until the sintered granules were installed in the vapor deposition apparatus was collected from a nylon bag for storage and sieved with a metal mesh screen having a nominal opening of 0.1 mm. The ratio (weight ratio) of the sieved fine powder to the sintered granules was defined as the fine powder generation rate. It can be said that the larger the fine powder generation rate, the more the sintered body obtained is brittle and difficult to handle (poor handling). When the fine powder generation rate reaches about 0.5%, it is very easy to handle the sintered body.

  Using the sintered granule from which fine powder was removed, splashing and evaluation of the deposited film were performed with an electron beam deposition apparatus in the following manner.

<Splash evaluation>
The sintered granules were placed in a copper hearth (crucible) of an electron beam evaporation apparatus, a glass substrate was placed on the sample stage, and the inside of the apparatus was evacuated to 5.0 × 10 ⁻⁴ Pa and decompressed. After decompression, a 250 mA electron beam was generated from an electron gun at an acceleration voltage of 6 kV, and the sintered granules were heated and melted. From the start of heating the sintered granules to the melting of the entire sintered granules, the copper hearth was visually observed from the window of the electron beam deposition apparatus, and the frequency of occurrence of splash was compared.

<Evaluation of vapor deposition film>
After confirming the dissolution of the entire sintered granule, the inside of the apparatus is adjusted to an oxygen atmosphere of 1.4 × 10 ⁻² Pa, and the current value of the electron beam is adjusted to a value at which the film formation rate is 0.3 nm / sec. And the vapor deposition film | membrane with an optical film thickness of 2lambda was produced | generated, keeping a glass substrate at 80 degreeC. About the obtained vapor deposition film, the peak of transmission / reflection was calculated | required with the spectrophotometer, the wavelength dispersion characteristic was calculated, and the refractive index in wavelength 560nm vicinity was calculated | required. In addition, the temperature of the glass substrate is lowered according to the temperature when the vapor deposition film is formed on the resin substrate (usually 250 ° C.).

  The weight ratio of each raw material in Examples 1 to 3 and Comparative Examples 1 to 4 is shown in Table 1, and the fine powder generation rate, the splash and the evaluation results of the deposited film, and the bulk density of the sintered granules or the melt are shown in Table 2. .

From Tables 1 and 2, by including the third subcomponent, the refractive index of the obtained vapor deposition film is stably 2.24 or more, and a high refractive index vapor deposition film can be obtained stably. I understand. On the other hand, it can be seen that when the first or second subcomponent is not present, there is a problem that the fine powder generation rate is increased or the splash is increased. Since the vapor deposition material of the present invention includes the first to third subcomponents, it has a performance similar to that of a melt while being a vapor deposition material of a sintered system. On the other hand, since it is a sintered vapor deposition material, there is no demerit such as the risk of crucible breakage due to differential thermal expansion or a decrease in yield due to adhesion to the crucible unlike a melt.

  By using the vapor deposition material of the present invention, a titanium dioxide vapor deposition film having high film quality can be formed even at a relatively low temperature. Therefore, the vapor deposition material of the present invention can be applied regardless of the material to be vapor deposited. Further, since the vapor deposition material of the present invention has a high yield and good handling, it is possible to form a titanium dioxide vapor deposition film with high film quality on a wide variety of materials at low cost and stably. As a result, various optical devices having a high refractive index and high heat resistance can be manufactured inexpensively and stably.

Claims (4)

A main component composed of a titanium oxide represented by a composition formula TiO _x (1.4 ≦ x ≦ 1.8);
A first subcomponent consisting of at least one selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide and ytterbium oxide;
A second subcomponent consisting of at least one selected from the group consisting of a compound having a garnet structure and yttrium oxide;
A third subcomponent comprising at least one alkaline earth metal titanate;
Vapor deposition material including a sintered body made of   The vapor deposition material according to claim 1, wherein the first subcomponent is aluminum oxide. The vapor deposition material according to claim 1 or 2 , wherein, in the third subcomponent, the alkaline earth metal titanate is at least one selected from the group consisting of strontium titanate and barium titanate. The first subcomponent, the sum of the second subcomponent and the third subcomponent is not more than 10 wt% 1 wt% or more with respect to the sintered body, any one of claims 1 to 3 The vapor deposition material according to one item.