JP5371373B2 - Alumina sintered body, semiconductor manufacturing apparatus member, liquid crystal panel manufacturing apparatus member, and dielectric resonator member - Google Patents

Description

  The present invention relates to an alumina sintered body, a member for a semiconductor manufacturing apparatus, a member for a liquid crystal panel manufacturing apparatus, and a member for a dielectric resonator, and in particular, an inner wall material (chamber), a microwave introduction window, a shower of a semiconductor manufacturing apparatus. Used in parts such as heads, focus rings, shield rings, liquid crystal panel manufacturing equipment stages, mirrors, mask holders, mask stages, chucks, reticles, and other high-frequency regions such as microwaves and millimeter waves. It can be suitably used for various resonator materials, MIC dielectric substrate materials, dielectric waveguide materials, and the like.

  Conventionally, sintered alumina has excellent heat resistance, chemical resistance, and plasma resistance, and also has a low dielectric loss tangent (tan δ) in the high frequency region. Used in containers.

  Semiconductor or liquid crystal panel manufacturing equipment members are in contact with highly reactive halogen-based corrosive gases used for etching and cleaning, and their plasmas, and therefore require high corrosion resistance, and generally 99.0 mass. % Or more high-purity alumina sintered body is required. On the other hand, the dielectric loss tangent increases from the viewpoint of sinterability as it becomes a high-purity alumina sintered body, which reduces the high-frequency transmittance in the MHz band, increases energy loss, and damages the member due to heat generation. Problems are known to occur.

For reducing the loss of the alumina sintered body, SiO ₂ , CaO, and MgO are included as sintering aids, and the content is controlled to be within a certain range. There is known an alumina sintered body with improved sinter (see, for example, Patent Document 1).

This Patent Document 1 is composed of 99.8 to 99.9% by mass of alumina and a grain boundary phase component composed of SiO ₂ , CaO, and MgO at a predetermined ratio, and the Q value at a measurement frequency of 8 GHz is 10,000 or more. It is described that an alumina sintered body for a microwave resonator having a dielectric loss tangent of 0.0001 or less was obtained.

  In addition, an alumina sintered body is obtained by containing anisotropic second-phase crystal particles made of a composite oxide with Al including at least one of La, Ca, Sr, Ba, Sm, Nd and Ti. An alumina sintered body with improved oxidation resistance and mechanical properties is known (see, for example, Patent Document 2).

In Patent Document 2, 1 to 20% by volume of second phase crystal particles having an average crystal grain size of the alumina matrix of 10 μm or less and a length in the major axis direction of 20 μm or more is present in the total amount of the sintered body. Thus, it is described that a fracture toughness value of 4.7 MPa · m ^1/2 and a room temperature strength of 580 MPa or more were obtained.
JP-A-6-16469 JP-A-8-208317

As in Patent Document 1, an alumina sintered body containing SiO ₂ , CaO, and MgO has a dielectric loss tangent of 0.0001 or less at a measurement frequency of 8 GHz. However, when an alumina sintered body is used for a large-sized product such as a member for a semiconductor manufacturing apparatus and a liquid crystal panel manufacturing apparatus, the density of the central part of the alumina sintered body is low. The dielectric loss tangent in the MHz band as a whole is large. For example, when used for a member for a high frequency plasma device for semiconductors in which a high frequency in the MHz band is used, the transmittance of the high frequency in the MHz band is reduced, resulting in energy loss. There are problems such as an increase in the number of members and breakage of members. Furthermore, in recent years, there are applications in a wide frequency range in the MHz to GHz band, and there has been a demand for a low dielectric loss tangent.

  Moreover, in patent document 2, 1-20 volume% of 2nd phase crystal particles exist in the sintered compact whole quantity, and although fracture toughness and room temperature strength are high, a dielectric loss tangent is low and the high frequency of a MHz band is used. When used as a member for a high-frequency plasma device for semiconductors, etc., there has been a problem that the high-frequency transmittance in the MHz band is reduced.

  An object of the present invention is to provide an alumina sintered body, a member for a semiconductor manufacturing apparatus, a member for a liquid crystal panel manufacturing apparatus, and a member for a dielectric resonator that can reduce the dielectric loss tangent in the MHz to GHz band.

As a result of intensive investigations aimed at reducing the dielectric loss tangent in the MHz to GHz band of the alumina sintered body, the present inventors contained Al in an amount of 99.3% by mass in terms of Al ₂ O ₃ , and alumina crystal particles The crystal phase or amorphous phase containing Si, Al, M (M is an alkaline earth metal , and at least Sr or Ba ) and O are present at the three points of Si, Al, M, and O. It has been found that an alumina-based sintered body having a low dielectric loss tangent can be obtained in a wide frequency range of MHz to GHz band by allowing a crystal phase containing bismuth to exist at a triple point of 10% or more of the triple points. It came to.

That is, the alumina-based sintered body of the present invention contains 99.3% by mass or more of Al in terms of Al ₂ O ₃ , and includes Si, Al, and M (M is an alkaline earth metal , and at least Sr Or containing Ba. ), And an alumina sintered body having alumina crystal particles as main crystal particles, the triple point composed of the alumina crystal particles in an arbitrary cross section of the alumina sintered body, There is a crystal phase containing Si, Al, M and O as an element, or an amorphous phase containing Si, Al, M and O as an element, and 10 out of three points composed of the alumina crystal particles The crystal phase containing Si, Al, M, and O as the element exists at a triple point of at least%.

In such an alumina sintered body, since Al is contained in an amount of 99.3% by mass or more in terms of Al ₂ O ₃ and the alumina crystal particles are the main crystal particles, the original excellent corrosion resistance and mechanical properties of alumina. In addition, the electrical characteristics can be maintained, and since the crystalline or amorphous phase containing Si, Al, M and O as elements exists at the triple point composed of alumina crystal particles, the element at the triple point When there is a crystalline phase such as SrAl ₂ Si ₂ O ₈ containing Si, Al, M and O as a low-dielectric loss tangent can be promoted, and when an amorphous phase exists at the triple point Since the sintered body is densified, defects and voids in the sintered body can be reduced, thereby achieving a low dielectric loss tangent.

  And since the low dielectric loss tangent crystal phase containing Si, Al, M, and O as elements exists in three points of 10% or more of the three points composed of alumina crystal particles, The dielectric loss tangent can be further reduced, and the dielectric loss tangent at a measurement frequency of 1 MHz to 8.5 GHz can be reduced.

Moreover, the alumina sintered body of the present invention is characterized in that the crystal phase containing Si, Al, M and O as the element comprises a MAl ₂ Si ₂ O ₈ type crystal phase. Since the MAl ₂ Si ₂ O ₈ type crystal phase has a low dielectric loss tangent in the region of 1 MHz to 8.5 GHz, it is highly effective in reducing the dielectric loss tangent of the alumina sintered body. In particular, it is effective in reducing dielectric loss tangent in the high frequency region. Furthermore, alkaline earth metal oxides function as a sintering aid, improve sinterability, and can reduce voids and defects even at the center of large sintered bodies, especially in the MHz band. Thus, a lower loss alumina sintered body can be obtained. Furthermore, since the sinterability is improved, for example, the central portion in the thickness direction of the thick sintered body having a large thickness is sufficiently sintered, and the mechanical strength of the entire large sintered body having a large thickness is The characteristics can be improved.

In addition, the alumina sintered body of the present invention is characterized by further containing at least one of crystal phases composed of compounds represented by MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ . The presence of these crystal phases can reduce the amorphous phase that increases the dielectric loss tangent in the GHz band, and can lower the dielectric loss tangent in the region of 1 MHz to 8.5 GHz. In particular, MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ are effective for lowering the dielectric loss tangent in the GHz band because the crystal itself has a low dielectric loss tangent.

  Furthermore, the alumina sintered body of the present invention is characterized in that the average particle diameter of the alumina crystal particles is 25 μm or more. In such an alumina sintered body, the grain boundary can be reduced by increasing the average particle diameter of alumina crystal particles to 25 μm or more, and the dielectric loss tangent at a measurement frequency of 1 MHz to 8.5 GHz can be further reduced. .

The member for a semiconductor manufacturing apparatus, the member for a liquid crystal panel manufacturing apparatus, and the member for a dielectric resonator according to the present invention are made of the above-mentioned alumina sintered body. Since the alumina sintered body has a dielectric loss tangent of 5 × 10 ⁻⁴ or less in the frequency range between 1 MHz and 8.5 GHz, the high frequency transmittance in the MHz to GHz band can be improved and energy loss is reduced. In addition, damage to the member due to heat generation can be suppressed.

In the alumina sintered body of the present invention, since Al is contained in an amount of 99.3% by mass or more in terms of Al ₂ O ₃ and the alumina crystal particles are the main crystal particles, the original excellent corrosion resistance and mechanical properties of alumina. In addition, the electrical characteristics can be maintained, and the crystalline or amorphous phase containing Si, Al, M and O as elements exists at the triple point composed of the alumina crystal particles. For example, SrAl ₂ Si _When a crystal phase such as ₂ O ₈ is present, low dielectric loss tangent can be promoted, and when an amorphous phase is present at the triple point, the sintered body is densified, By reducing defects and voids in the body, this can achieve low dielectric loss tangent, and furthermore, the crystalline phase of low dielectric loss tangent exists at the triple point of 10% or more of the triple points, so alumina-based sintering Can further reduce the body's dielectric loss tangent. You can further reduce the dielectric loss tangent at a measuring frequency 1MHz～8.5GHz, dielectric loss tangent 5 × ^{10 -4} or less at a measuring frequency 1 MHz, and a dielectric loss tangent 5 × ^{10 -4} or less at a measuring frequency 8.5GHz Can be achieved.

  Therefore, by using the alumina sintered body of the present invention as a member for a semiconductor manufacturing apparatus member, a liquid crystal panel manufacturing apparatus member and a dielectric resonator member, highly reactive halogen-based corrosive gases and their Since it has high corrosion resistance to plasma and the alumina sintered body has low loss in the MHz to GHz band, it can improve the high frequency transmittance in the MHz to GHz band, reduce energy loss, It is possible to promote low dielectric loss tangent of the entire device.

The alumina sintered body of the present invention contains Al in an amount of 99.3% by mass or more in terms of Al ₂ O ₃ and 0.7% by mass or less of other subcomponents. By containing 99.3% by mass of alumina and using alumina crystal particles as the main crystal particles, it is possible to improve the sinterability and maintain the excellent corrosion resistance, mechanical properties, and electrical properties of alumina. It becomes. When the amount of the auxiliary component is 0.7% by mass or more, it leads to a decrease in mechanical / electrical characteristics and a decrease in corrosion resistance. Therefore, it is preferable that Al is 99.3% by mass or more in terms of Al ₂ O ₃ and the subcomponent is 0.7% by mass or less.

Furthermore, in order to apply as a member for a semiconductor or liquid crystal panel manufacturing apparatus, it is necessary to have excellent corrosion resistance against plasma under a halogen-based gas. Therefore, Al is 99.5% by mass or more in terms of Al ₂ O ₃ , and a subsidiary component Is preferably 0.5% by mass or less. Examples of the halogen-based gas include fluorine-based gases such as SF ₆ , CF ₄ , CHF ₃ , ClF ₃ , NF ₃ , C ₄ F ₈ , and HF, and chlorine-based gases such as Cl ₂ , HCl, BCl ₃ , and CCl _4. There is a gas or a bromine-based gas such as Br ₂ , HBr, or BBr ₃ . In order to enhance the etching effect of semiconductors, liquid crystal panels, etc., plasma may be generated by introducing an inert gas such as Ar together with the halogen-based gas.

  Alumina is desirably 99.9% by mass or less from the viewpoint of sinterability. Furthermore, the triple point composed of alumina crystal particles contains a crystal phase composed of a compound containing Si, Al, M (M is an alkaline earth metal) and O as elements, or Si, Al, M and O as elements. An amorphous phase exists. FIG. 1 shows a schematic cross-sectional view of an alumina sintered body. Reference numeral 1 is alumina crystal particles, and reference numeral 2 is a triple point (grain boundary).

  In the present application, the triple point 2 constituted by the alumina crystal particles 1 is a grain boundary formed by three or more alumina crystal particles 1, and a two-plane grain boundary 5 constituted by two alumina crystal particles 1. Is different. Many triple points 2 are observed in an arbitrary cross section of the sintered body, but many triple points 2 have a crystal phase composed of a compound containing Si, Al and M (M is an alkaline earth metal) as elements, or non- A crystalline phase is present. Further, in the triple point 2, there is a case where these crystal phases or amorphous phases are not present and other crystal phases are present.

When a crystal phase composed of a compound containing Si, Al, M and O as an element, for example, a low dielectric loss tangent crystal phase such as SrAl ₂ Si ₂ O _8, is present at the triple point 2 composed of the alumina crystal particles 1 In this case, the low dielectric loss tangent at MHz to GHz can be directly promoted by the presence of the crystalline phase, and when the amorphous phase is present at the triple point, the sintered body is densified. , Defects and voids in the sintered body can be reduced, thereby achieving a low dielectric loss tangent at MHz.

  And in this invention, in the arbitrary cross section of a sintered compact, it is from the compound containing Si, Al, M, and O as an element in the triple point 2 of 10% or more among the triple points 2 comprised by the alumina crystal particle 1. This is characterized by the presence of a crystalline phase. The crystal phase is present at the triple point 2 of 10% or more of the triple points 2 composed of the alumina crystal particles 1. Of the numerous triple points 2 composed of the alumina crystal particles 1 in a predetermined area of an arbitrary cross section. This means that a crystal phase composed of a compound containing Si, Al, M and O exists in at least 10% of the above.

  In the present invention, since at least 10% of the many triple points 2 has a crystal phase composed of a compound containing Si, Al, M and O, as described later, the raw material powder constituting the crystal phase The mixed powder is added to the alumina powder. In the case where the raw material powders of Si, Al, and M are individually added to the alumina powder as in the prior art, Si, Al, and M are present in a biased manner at the triple point 2 of the alumina crystal particles 1 and are amorphous. Although there is a possibility that a crystal phase composed of a compound containing Si, Al, M and O exists slightly as a phase or a crystal phase having a high dielectric loss tangent, as in the present invention, a large number of triple points 2 At least 10% of them could not have a crystal phase containing Si, Al, M and O, and there was a tendency to increase the dielectric loss tangent of the entire alumina sintered body.

  Thus, since the low dielectric loss tangent crystal phase is present at the triple point 2 of 10% or more of the triple points 2, the alumina sintered body can be made to have a low dielectric loss tangent. In order to lower the dielectric loss tangent in the frequency region between 1 MHz and 8.5 GHz, the ratio of the grain boundary triple point 2 where the crystal phase containing Si, Al, M and O of low dielectric loss tangent is 20% or more. Is preferred. Further, the ratio of the grain boundary triple point 2 where the crystal phase of low dielectric loss tangent exists is less than 60%.

  In the present invention, the triple point 2 composed of the alumina crystal particles 1 and the triple point 2 where the crystal phase does not exist has an amorphous phase containing Si, Al, M and O as elements. May exist. The triple point 2 where the amorphous phase exists is desirably 90% or less, particularly 80% or less in a predetermined area of an arbitrary cross section. As described above, the denseness of the sintered body can be improved by the presence of the amorphous phase, but the amorphous phase itself increases the dielectric loss tangent.

From the viewpoint of electrical characteristics, a low-loss crystal phase composed of a compound containing Si, Al, M (M is an alkaline earth metal) and an O element is an MAl ₂ Si ₂ O ₈ type crystal (M is an alkaline earth). Metal), and the generation of this crystal can reduce the dielectric loss tangent. As a low-loss crystal phase composed of a compound containing Si, Al, M (M is an alkaline earth metal) and an O element, other than the stoichiometric composition of MAl ₂ Si ₂ O ₈ , stoichiometric composition It may be a little off.

  Examples of the alkaline earth metal include Mg, Ca, Sr, and Ba, and Mg, Ca, and Sr are preferable from the viewpoints of dielectric properties and sinterability. Among these, Sr is particularly preferable from the viewpoint of low dielectric loss tangent.

Conventionally, alkaline earth metals such as Mg and Ca have been known as sintering aids, but among alkaline earth metals, Sr and Ba are not used as sintering aids because of their large ionic radii. In particular, there is no example of positive use of Sr. In the present invention, in particular, Sr is not used as a sintering aid, but is used for precipitating a crystal phase of SrAl ₂ Si ₂ O ₈ , which is a low dielectric loss tangent crystal phase. Therefore, the dielectric loss tangent of the alumina sintered body can be lowered directly.

In the present invention, the compound represented by the MAl ₂ Si ₂ O ₈ type crystal may be one in which a part of the constituent element of M is substituted with another element.

In the alumina sintered body of the present invention, the measurement frequency is 1 MHz to 8 by setting the dielectric loss tangent at a measurement frequency of 1 MHz to 5 × 10 ⁻⁴ or less and the dielectric loss tangent at a measurement frequency of 8.5 GHz to 5 × 10 ⁻⁴ or less. Even in the frequency region between 5 GHz, the dielectric loss tangent can be expected to be 5 × 10 ⁻⁴ or less. From the viewpoint of expecting a lower dielectric loss tangent of 2 × 10 ⁻⁴ or lower in the above frequency range, the dielectric loss tangent of the measurement frequency 1 MHz is 2 × 10 ⁻⁴ or lower and the dielectric loss tangent of 8.5 GHz is 2 × 10 ⁻⁴ or lower. It is preferable that

That is, the dielectric loss tangent of the alumina sintered body is measured at a frequency of 1 MHz, and it is confirmed that there is almost no increase in the dielectric loss tangent due to space charge polarization, interface polarization, and dipole polarization by confirming that it is 5 × 10 ⁻⁴ or less. it can. Moreover, since the peak due to the increase in the dielectric loss tangent due to these factors is in a frequency band lower than 1 MHz or in the vicinity of several MHz, these factors are observed up to around 1 GHz by confirming 5 × 10 ⁻⁴ or less at 1 MHz. It is expected that there is almost no increase in the dielectric loss tangent due to.

Further, by confirming that the dielectric loss tangent is 8.5 × 10 ⁻⁴ or less at 8.5 GHz, it can be confirmed that there is no increase in dielectric loss tangent due to ion polarization. Moreover, the peak due to the increase of the dielectric loss tangent due to ion polarization occurs in a frequency band higher than 8.5 GHz or a frequency of several GHz nearby, and by confirming a frequency of 5 × 10 ⁻⁴ or less at 8.5 GHz, it reaches about 1 GHz. Can be expected not to increase the dielectric loss tangent due to the factor of ion polarization.

Therefore, by confirming 5 × 10 ⁻⁴ or less at 1 MHz and 5 × 10 ⁻⁴ or less at 8.5 GHz, the dielectric loss tangent is also in the frequency region between 1 MHz and 8.5 GHz, particularly between 10 MHz and 1 GHz. Can be expected to be 5 × 10 ⁻⁴ or less.

Moreover, it is desirable that the alumina sintered body of the present invention further contains at least one of crystal phases composed of compounds represented by MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ . By generating these crystal phases, the amorphous phase that increases the dielectric loss tangent can be reduced, and the dielectric loss tangent can be lowered in the region of 1 MHz to 8.5 GHz. In particular, MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ have a low dielectric loss tangent in the GHz band, and are therefore effective in reducing the dielectric loss tangent in the GHz band of an alumina sintered body.

Further alumina sintered body of the present invention is preferably an average particle diameter D ₅₀ of the alumina crystal particles is 25μm or more. Thereby, the dielectric loss tangent can be stably reduced. From the viewpoint of more stable low dielectric loss tangent, the average particle diameter D ₅₀ of the alumina crystal particles is preferably at least 40 [mu] m. The average particle diameter D ₅₀ of the alumina crystal particles, from the viewpoint of mechanical properties, is desirably 70μm or less. Incidentally, the average particle diameter D _50, refers to the particle size of cumulative 50% fine particle side of the cumulative particle size distribution.

  The alumina-based sintered body of the present invention is used as a part for industrial machinery, and can be suitably used as a large and thick member used particularly for a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus. The member for a semiconductor manufacturing apparatus in the present invention means an inner wall material (chamber), a microwave introduction window, a shower head, a focus ring, a shield ring, or the like of the semiconductor manufacturing apparatus. A member for a liquid crystal panel manufacturing apparatus refers to a stage, a mirror, a mask holder, a mask stage, a chuck, a reticle, and the like.

  Furthermore, the alumina sintered body of the present invention is also used as a dielectric resonator, a dielectric substrate for MIC, a waveguide or the like in a high frequency region such as a microwave or a millimeter wave. In particular, it can be suitably used as a support for various dielectric resonators.

The method for producing an alumina sintered body of the present invention is, for example, by preparing a raw material powder in which a Si source and an alkaline earth metal source are weighed and mixed in advance at a composition ratio for generating MAl ₂ Si ₂ O ₈ type crystals, The raw material powder is added to the alumina powder, molded, and then fired at 1500 to 1800 ° C.

The raw material powder obtained by mixing the alkaline earth metal source and the Si source is obtained by weighing the Si source and the alkaline earth metal source at a predetermined ratio for generating MAl ₂ Si ₂ O ₈ type crystals, It is a powder obtained by mixing. The Si source and alkaline earth metal source here may be any of salts such as metals, oxides, hydroxides, carbonates, nitrates and the like. By using a mixed powder of Si and alkaline earth metal mixed, the distribution of Si and alkaline earth metal in the alumina sintered body is made uniform, and the generation of MAl ₂ Si ₂ O ₈ type crystals is promoted. In addition, a non-uniform sintered structure can be suppressed.

By using a mixed powder of a Si source and an alkaline earth metal source mixed at a composition ratio that generates MAl ₂ Si ₂ O ₈ type crystals, a reaction between Si and the alkaline earth metal is preferentially caused to produce alumina crystals. A crystal having a low dielectric loss tangent composed of Si, an alkaline earth metal, Al, and an O element, for example, MAl ₂ Si ₂ O ₈ type crystal, between the particles, a triple point of 10% or more of the three points composed of alumina crystal particles It is possible to exist in If the distribution of Si and alkaline earth metal is not uniform, a large amount of amorphous phase is formed, or a crystalline phase with a high dielectric loss tangent is generated, which increases the dielectric loss tangent of the entire alumina sintered body. Become. In addition, the number of processes can be reduced and the cost can be reduced as compared with the case of calcining a mixed powder of an Si source and an alkaline earth metal source mixed at a composition ratio that generates MAl ₂ Si ₂ O ₈ type crystals. Can do.

  A mixed powder obtained by mixing the alkaline earth metal source and the Si source with the alumina powder and a raw material powder containing the Mg source may be mixed and fired. As the Mg source, it is possible to use salts such as metals, metal oxides, metal hydroxides, and metal carbonates as powders or aqueous solutions. Furthermore, a mixed powder containing an alkaline earth metal source, a Si source, and a Mg source may be produced, and this mixed powder may be added to an alumina powder, molded, and fired.

  For molding, a molding method such as press molding, casting, cold isostatic pressing, or cold isostatic pressing can be used. Next, the obtained molded body is fired in a temperature range of 1500 to 1800 ° C. As a result, a sintered body having a high density and a crystal phase made of a compound containing Si, an alkaline earth metal, Al, and an O element is produced at the grain boundaries of the alumina crystal particles.

Next, the sintered body a dielectric loss tangent were measured at a measuring frequency of 1MHz and 8.5 GHz, 1MHz at 5 × ^{10 -4} or less, by using non-defective ones to be 5 × ^{10 -4} or less at 8.5 GHz, The dielectric loss tangent can be expected to be 5 × 10 ⁻⁴ or less even in the frequency region between the measurement frequencies of 1 MHz to 8.5 GHz. As a result, it is possible to use a highly accurate capacitance meter (Hewlett Packard: HP-4278A) and network analyzer (Agilent Technology: 8722ES) with respect to the dielectric loss tangent, and 1 MHz to 8 which cannot be guaranteed by a conventional impedance analyzer. It is possible to design a low dielectric loss tangent material in the 5 GHz band. The frequency measured by the network analyzer may deviate somewhat from 8.5 GHz.

That is, conventionally, the dielectric loss tangent at a measurement frequency of 1 MHz is measured using a capacitance meter (HP-4278A), and the dielectric loss tangent at a measurement frequency of 8.5 GHz is measured using a cavity resonator method (network analyzer 8722ES). Are known to obtain accurate dielectric loss tangents of ± 2 × 10 ⁻⁴ or less and ± 0.1 × 10 ⁻⁴ or less, respectively, but from 1 MHz required for semiconductor and liquid crystal panel manufacturing apparatus members In the frequency region of 8.5 GHz, particularly 10 MHz to 1 GHz, there is only measurement using an impedance analyzer (HP-4291A, manufactured by Hewlett-Packard Company), and the measurement error is about ± 30 × 10 ⁻⁴ even if it is small, 5 × 10 Measurement accuracy is very low for dielectric loss tangent of ^-4 or less.

Therefore, the dielectric loss tangent at the measurement frequency of 1 MHz and 8.5 GHz is indirectly measured without directly measuring the dielectric loss in the frequency domain from 1 MHz to 8.5 GHz with an impedance analyzer with low measurement accuracy, and the measurement frequencies of 1 MHz and 8 are measured. If the dielectric loss tangent at .5GHz is in the range of 5 × ^{10 -4} or less, measurement frequency 1MHz～8.5GHz, particularly a 5 × ^{10 -4} or less dielectric loss tangent in the frequency region between 10~100MHz The dielectric loss tangent at the measurement frequency of 1 MHz to 8.5 GHz can be estimated easily and accurately.

First, powders of SiO ₂ , SrCO ₃ , CaCO ₃ , and BaCO ₃ were weighed so as to produce MAl ₂ Si ₂ O ₈ type crystals, and dry-mixed to obtain a raw material powder.

The raw material powder and Mg (OH) ₂ powder are added to 99.95% pure Al ₂ O ₃ powder, and a predetermined amount of water is added thereto and mixed in an alumina ball mill for 48 hours to form a slurry. . The slurry was added to the slurry, dried, granulated, and molded with a pressure of 1 t / cm ² to produce a cylindrical molded body (diameter 60 mm × height 30 mm), and 1670 ° C. in the atmosphere. The alumina sintered body having a diameter of 50 mm and a height of 25 mm was obtained.

Sample No. In No. 1, SiO ₂ powder, SrCO ₃ powder, CaCO ₃ powder, and Mg (OH) ₂ powder are separately added to 99.95% pure Al ₂ O ₃ powder, and a predetermined amount of water is added thereto. The mixture was mixed with a ball mill for 48 hours to form a slurry. The slurry was added to the slurry, dried, granulated, and molded with a pressure of 1 t / cm ² to produce a molded body (diameter 60 mm × height 30 mm). Firing was performed at temperature.

Sample No. In No. 14, SiO ₂ powder, CaCO ₃ powder, and Mg (OH) ₂ powder were separately added to 99.95% pure Al ₂ O ₃ powder, and a predetermined amount of water was added thereto, and then 48 Mix for a time to make a slurry. The slurry is added to the slurry, dried, granulated, and the mixed powder is molded at a pressure of 1 t / cm ² to produce a molded body (diameter 60 mm × height 30 mm). Firing was performed at a temperature of.

Quantitative analysis of the elements of this alumina sintered body is performed by ICP emission spectroscopic analysis. In Table 1, Al is converted to Al ₂ O ₃ , Si is converted to SiO ₂ , Sr is converted to SrO, and Mg is converted to MgO. , Ca is described in terms of CaO, and Ba is described in terms of BaO. In addition, elements other than Al, Si, Sr, Mg, Ca, and Ba are used as the balance, and their amounts are also described. The balance was mainly Na ₂ O and Fe ₂ O ₃ . Further, it was confirmed by X-ray diffraction measurement that all the samples were mainly composed of alumina crystal particles. Further, the presence or absence of a crystal phase composed of compounds represented by MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ was confirmed by X-ray diffraction measurement and listed in Table 1.

  A sample having a thickness of 1 mm was cut out from the center in the height direction of the obtained sintered body, and the density and dielectric loss tangent were measured. The density was measured by the Archimedes method.

The dielectric loss tangent tan δ is measured at 1 MHz, 12 MHz, and 8.5 GHz, and measured using a capacitance meter (HP-4278A), impedance analyzer (HP-4291A), and cavity resonator method (network analyzer 8722ES), respectively. I did it. Although the measurement error of the capacitance meter is ± 2 × 10 ⁻⁴ or less and the measurement error of the cavity resonator method is ± 0.1 × 10 ⁻⁴ or less, the measurement error of the impedance analyzer is ± 30 × 10 ^−4. Therefore, when the 12 MHz dielectric loss tangent by the impedance analyzer is less than 5 × 10 ⁻⁴ , it is described in Table 1 as <5.

  In addition, the frequency dependence of the dielectric loss tangent at 1 MHz to 1 GHz was also confirmed by an impedance analyzer. As a result, the dielectric loss tangent at 1 MHz to 1 GHz in this sample tends to be high at 1 to 10 MHz and 100 MHz to 1 GHz and low in the frequency band between them, particularly at 10 to 100 MHz. Tended to be low. Moreover, no peak was observed in the dielectric loss tangent in the frequency band of 10 to 100 MHz, and the shape was flat.

  First, using a network analyzer, a sample having a diameter of 50 mm × thickness of 1 mm is sandwiched by a jig to obtain a dielectric loss tangent at 8.5 GHz. Next, using an impedance analyzer, the sample having a diameter of 50 mm × thickness of 1 mm is fixed to the jig. Then, the dielectric loss tangent at 12 MHz was obtained. After that, electrodes were formed on the upper and lower surfaces of the sample having a diameter of 50 mm and a thickness of 1 mm based on JIS C2141, and the dielectric loss tangent at 1 MHz was obtained with a capacitance meter.

Moreover, the analysis of the crystal phase in each sintered body is performed by energy dispersive X-ray spectroscopy (EDS) and limited-field electron diffraction using a transmission electron microscope (TEM), and Si, Al, M ( M = Ca, Sr, Ba), a low-loss crystal phase composed of a compound containing an O element, and the presence or absence of MAl ₂ Si ₂ O ₈ , 30 grain boundaries were confirmed at 30 points per sample, and MAl ₂ Si ₂ Table 2 shows the generation ratio of the O ₈ type crystal phase and the generation ratio of the amorphous phase. In addition, it was confirmed by the limited visual field electron diffraction whether it was an amorphous phase. In FIG. 12 electron diffraction images were shown.

Further, the average particle diameter _{D 50} of the alumina crystal particles, the scanning electron micrograph of the sample (500 fold) in the range of 0.0432Mm ^2, determine the diameter of each crystal grain in an image analyzer, the average particle calculating the diameter _{D 50,} as described in Table 2.

From Tables 1 and 2, the triple point composed of alumina crystal particles is produced by the formation of a crystal phase or an amorphous phase composed of a compound containing Si, Al, M, and O elements. In the sample of the present invention in which a crystal phase containing Si, Al, M and O as elements is present at the triple point of 10% or more, the dielectric loss tangent is 2.3 × 10 ⁻⁴ or less at 8.5 GHz. In addition, in the case of 2 × 10 ⁻⁴ or less at 1 MHz, it is found that the loss is 5 × 10 ⁻⁴ or less even at 12 MHz.

On the other hand, Sample No. _{2 was} prepared by separately adding SiO ₂ powder, SrCO ₃ powder, CaCO ₃ powder, and Mg (OH) ₂ powder to the alumina powder. 1 shows that the ratio of the triple point where the crystal phase containing Si, Al, M and O exists is as small as 3%, and the dielectric loss tangent at 8.5 GHz and 1 MHz is large.

In addition, sample No. 1 in which SiO ₂ powder, CaCO ₃ powder, and Mg (OH) ₂ powder were separately added to the alumina powder. 14, although the crystal phase composed of Si, Ca, Al, and O element exists at the triple point of the aluminum oxide crystal particles, the triple point where the crystal phase exists is as low as 3%, and 1.4 × at 8.5 GHz. Although the loss was as low as 10 ⁻⁴ or less, it was as high as 40 × 10 ^{−4 at} 1 MHz and 7 × 10 ^{−4 at} 12 MHz, and the dielectric loss was high in the MHz band.

The alumina sintered body of this invention is shown, (a) is a SEM photograph, (b) is a schematic diagram. Sample Nos. 12 is a TEM photograph and an electron diffraction image, (a) is a TEM photograph and an electron diffraction image showing a crystal phase containing Si, Al, and M at the triple point, and (b) is at the triple point. It is the TEM photograph and electron diffraction image which show the place where the amorphous phase containing Si, Al, M, and O exists.

Explanation of symbols

1 ... Alumina crystal particles 2 ... 3 points

Claims (7)

Al is contained in an amount of 99.3% by mass or more in terms of Al ₂ O ₃ , Si, Al, and M (M is an alkaline earth metal and contains at least Sr or Ba ) as elements, and alumina. An alumina sintered body having crystal grains as main crystal particles, and containing Si, Al, M, and O as elements at the triple point composed of the alumina crystal particles in an arbitrary cross section of the alumina sintered body Crystal phase, or an amorphous phase containing Si, Al, M and O as elements, and at least 3% of the three points composed of the alumina crystal particles, Si as the element An alumina sintered body characterized in that the crystal phase containing Al, M, and O exists. _2. The alumina sintered body according to claim 1, wherein the crystal phase containing Si, Al, M, and O as the element is an MAl ₂ Si ₂ O ₈ type crystal phase. The alumina-based sintered body according to claim 1 or 2, further comprising at least one of crystal phases composed of compounds represented by MgAl ₂ O ₄ and CaAl ₁₂ O ₁₉ . The alumina sintered body according to any one of claims 1 to 3, wherein an average particle diameter of the alumina crystal particles is 25 µm or more. A member for a semiconductor manufacturing apparatus, comprising the alumina sintered body according to any one of claims 1 to 4. A member for a liquid crystal panel manufacturing apparatus, comprising the alumina sintered body according to any one of claims 1 to 4. A dielectric resonator member comprising the alumina sintered body according to any one of claims 1 to 4.