JP4889223B2 - Aluminum oxide sintered body, semiconductor manufacturing apparatus member using the same, and liquid crystal manufacturing apparatus member - Google Patents

Description

  The present invention relates to an aluminum oxide sintered body, a semiconductor manufacturing apparatus member using the same, and a liquid crystal manufacturing apparatus member.

Currently, aluminum oxide sintered bodies are widely used in electronic parts and industrial machine parts. Since the aluminum oxide sintered body used for these is required to have excellent electrical characteristics, mechanical characteristics, chemical resistance, and plasma resistance, the content of Na ₂ O is generally 0.1. % Of low soda aluminum oxide is used. In the manufacturing process of the soda aluminum oxide used here, when aluminum hydroxide which is a precursor of aluminum oxide is calcined, silicon oxide particles and aluminum chloride are added, and Na contained in the aluminum hydroxide is added. A method of removing ₂ O by adsorption or reaction is common.

  Regarding an aluminum oxide sintered body used for a member for a semiconductor manufacturing apparatus, Patent Document 1 describes a method for manufacturing a high-purity aluminum oxide sintered body in which the impurity content is extremely reduced. That is, the alkali metal oxide in the aluminum oxide sintered body is 50 ppm or less and the magnesium oxide content is 100 ppm, and further, by suppressing and controlling the mixing of alkali metal from the manufacturing process, there are few impurities and aluminum oxide An abnormal grain growth can be suppressed, and an aluminum oxide sintered body excellent in plasma resistance can be obtained.

Patent Document 2 describes a member for a semiconductor manufacturing apparatus that has little absorption of microwaves and prevents generation of cracks and is excellent in productivity. That is, an aluminum oxide sintered body having an aluminum oxide content of 99.9% or more, silica of less than 100 ppm, and an alkali metal oxide content of 50 ppm or less, a specific gravity of 9.6 or more, an average particle diameter of 10 μm or more, and a dielectric loss tangent of 8 × 10 ^When it is ^-4 or less, it has excellent plasma resistance and can prevent generation of cracks due to microwaves.
JP-A-6-157132 JP-A-5-217946

  In recent years, parts for industrial machines, especially semiconductor manufacturing equipment members and liquid crystal manufacturing equipment parts, are being used for such devices as the size of the devices is increasing. An aluminum oxide sintered body is no exception.

  In particular, molding and firing are problems when producing a large-sized aluminum oxide sintered body. In order to obtain a large and thick aluminum oxide sintered body, when the molded body is to be fired, the temperature distribution occurs inside and near the surface of the molded body during the sintering process, so the vicinity of the surface is sintered first. Is easier to proceed. For this reason, the sintered state is often different between the vicinity of the surface and the inside. That is, due to the fact that the sintering does not proceed uniformly, the vicinity of the surface becomes a dense sintered body first, and the inside becomes a sintered body in which crystals do not grow sufficiently and there are many voids. In order to solve such a phenomenon, a contrivance such as a manufacturing method as shown in Patent Document 1 and an extremely slow firing temperature increase in a temperature range where sintering proceeds has been made. A sufficient effect is not obtained and productivity is poor.

  Although the aluminum oxide sintered body obtained by the manufacturing method shown in Patent Document 1 suppresses and controls the mixing of alkali metals from the manufacturing process, the aluminum oxide powder that is usually used is a buyer method. Since a substance containing phosphorus is used in the soda removal step for converting the obtained aluminum oxide into a low soda aluminum oxide, it is common that the obtained soda aluminum oxide also contains phosphorus. . The phosphorus content exceeds 0.0025% by weight, and there is a problem that uniform grain growth is inhibited particularly in a large-sized aluminum oxide sintered body.

Similarly, although the aluminum oxide sintered body shown in Patent Document 2 can also obtain the characteristics of specific gravity of 9.6 or more, average particle diameter of 10 μm or more, and dielectric loss tangent of 8 × 10 ⁻⁴ or less, Similar to Patent Document 1, there is no knowledge about grain growth inhibition by phosphorus contained in raw soda aluminum oxide.

  Therefore, in the conventional aluminum oxide sintered body, the difference between the density in the vicinity of the surface and the density in the interior is increased due to the difference in the sintering state between the vicinity of the surface and the interior as described above. The aluminum oxide sintered body has a large dielectric loss tangent value, and when these aluminum oxide sintered bodies are used as a member for semiconductor manufacturing equipment, the microwave permeability is deteriorated, so that the aluminum oxide sintered body is deteriorated. There was a problem that the body generated heat and cracks were generated, which shortened the life as a member for a semiconductor manufacturing apparatus.

The aluminum oxide sintered body of the present invention is an aluminum oxide sintered body containing an aluminum oxide having a content of 99% by weight or more and at least one selected from magnesium oxide, calcium oxide and silicon oxide. In addition, phosphorus is contained, and 0.0025 part by weight or less of phosphorus is contained with respect to 100 parts by weight of the aluminum oxide sintered body.

Moreover, the density difference inside the sintered body is 0.05 g / cm ³ or less.

Further, the dielectric loss tangent is 10 × 10 ⁻⁴ or less.

  Furthermore, the content of the aluminum oxide is 99.2% by weight or more.

  Furthermore, the magnesium oxide is 0.05% by weight or more and the crystal grain size is 10 μm or less.

  Moreover, it is the member for semiconductor manufacturing apparatuses characterized by consisting of the aluminum oxide sintered body of this invention.

  Moreover, it is the member for liquid crystal manufacturing apparatuses characterized by consisting of the aluminum oxide sintered body of this invention.

According to the present invention, an aluminum oxide sintered body comprising aluminum oxide having a content of 99% by weight or more and at least one selected from magnesium oxide, calcium oxide and silicon oxide , In addition, since the aluminum oxide sintered body contains 0.0025 parts by weight or less of phosphorus with respect to 100 parts by weight of the aluminum oxide sintered body, the aluminum oxide has a uniform structure with a small difference between the density near the surface and the internal density. A quality sintered body can be obtained.

In addition, since the density difference inside the sintered body is 0.05 g / cm ³ or less, the dielectric loss tangent value of the aluminum oxide sintered body is reduced and the microwave permeability is improved, so that the aluminum oxide sintered body is improved. It is possible to suppress the occurrence of cracks due to heat generation of the bonded body, and it is possible to suppress the deterioration of the life as a member for a semiconductor manufacturing apparatus.

Furthermore, since the dielectric loss tangent is 10 × 10 ⁻⁴ or less, the microwave permeability can be controlled better, and the generation of cracks due to heat generation of the aluminum oxide sintered body can be suppressed well.

  Furthermore, since the aluminum oxide content is 99.2% by weight or more, an aluminum oxide sintered body having good plasma resistance and chemical resistance can be obtained.

  Furthermore, since the magnesium oxide content is 0.05% by weight or more and the average crystal grain size is 10 μm or less, a dense sintered body with few voids is obtained, and the mechanical strength is kept high. In addition, it is possible to prevent a decrease in dielectric loss tangent due to voids and to satisfactorily suppress the generation of cracks due to heat generation of the aluminum oxide sintered body.

  In addition, the semiconductor manufacturing apparatus member using the aluminum oxide sintered body of the present invention has excellent plasma resistance and chemical resistance, and can obtain performance excellent in durability and stability of plasma processing speed such as etching. it can.

  In addition, the liquid crystal manufacturing apparatus member using the aluminum oxide sintered body of the present invention is excellent in plasma resistance and chemical resistance, and can obtain performance excellent in durability and stability of plasma processing speed such as etching. it can.

  Hereinafter, embodiments of the present invention will be described in detail.

  The present inventor has found that the presence of phosphorus contained in the aluminum oxide sintered body is greatly influenced in the sintering process of the large aluminum oxide sintered body. In other words, the presence of phosphorus hinders the promotion of uniform sintering, leaving many voids inside the sintered body during the sintering process. Further, there is a difference between the average crystal grain size near the surface and the average crystal grain size inside the sintered body.

The aluminum oxide sintered body of the present invention contains 99% by weight or more of aluminum oxide, and further contains at least one selected from magnesium oxide, calcium oxide and silicon oxide. This aluminum oxide sintered body contains phosphorus and contains phosphorus in a proportion of 0.0025 parts by weight or less with respect to 100 parts by weight of the sintered body.

  When the phosphorus content is 0.0025 parts by weight or less, the function of inhibiting the uniform sintering of aluminum oxide is not observed. This phenomenon acts as a strong sintering aid for phosphorus and promotes sintering in the vicinity of the sintered body surface, where heat is easily applied during the sintering process. This is thought to be caused by being left behind. On the other hand, if the phosphorus content exceeds 0.0025 parts by weight, a uniform sintered body is inhibited, and a sintered body in which many voids are present is obtained. The difference in density becomes large.

  In addition, it is specified as a high purity aluminum oxide sintered body having an aluminum oxide content in the aluminum oxide sintered body of 99% by weight or more. It becomes susceptible to impurities. In particular, the presence of phosphorus has a large influence on the sintering process of aluminum oxide, and is likely to appear as a void or a density difference between the inside and outside of the sintered body. On the other hand, when the content of aluminum oxide is less than 99% by weight, liquid phase sintering becomes the main component, so that impurities such as phosphorus have little influence on the sintering process. Therefore, it is unlikely to be a factor that hinders the sintering process.

  In addition, the auxiliary component constituting the balance other than aluminum oxide includes at least one of magnesium oxide, calcium oxide, and silicon oxide, thereby enabling firing at a sintering temperature considering mass productivity. When these are not contained, a firing temperature exceeding 1700 ° C. is required, which is not realistic.

  In addition, the content of these subcomponents is in the range of 0.8% to 0.05% by weight in terms of oxides, and if the subcomponent exceeds 0.8% by weight, the plasma resistance and chemical resistance decrease. However, it is not preferable as a member for a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus. When the minor component is less than 0.05% by weight, it is not a sufficient sintering aid in the sintering process of the aluminum oxide sintered body, and it becomes difficult to obtain a dense sintered body.

  Particularly preferred phosphorus content is 0.0020 parts by weight or less, and further 0.0015 parts by weight or less. If it is 0.0020 parts by weight or less, it is possible to make the difference in density between the surface vicinity and the inside of the aluminum oxide sintered body more uniform, and if it is 0.0015 parts by weight or less, particularly aluminum oxide. This is because when the purity is as high as 99.5% or more, it works effectively by keeping the density difference uniform.

  The phosphorus content is measured by ICP emission spectroscopic analysis. To make the phosphorus content in the aluminum oxide sintered body 0.0025 parts by weight or less, use as described in detail later. In addition, it is necessary to keep the total phosphorus content in the raw materials to be 0.0025 parts by weight or less and to be careful of contamination from the process. In particular, it is important to suppress the phosphorus content in the aluminum oxide powder, which is the main component, and the phosphorus content in the aluminum oxide powder is 0.0025 parts by weight or less.

Furthermore, the aluminum oxide sintered body of the present invention desirably has a density difference within the sintered body of 0.05 g / cm ³ or less.

  As a result, the dielectric loss tangent value is reduced, and the microwave transmission is improved, so that the generation of cracks due to heat generation of the aluminum oxide sintered body can be suppressed, and the life of the semiconductor and liquid crystal manufacturing apparatus is deteriorated. Can be suppressed. This is because, by setting the phosphorus content to 0.0025% by weight or less, the vicinity of the surface and the inside are uniformly grown during firing, and voids remaining inside can be reduced, thereby reducing the density difference. This is because it can.

On the other hand, when the density difference exceeds 0.05 g / cm ³ , there are many voids inside, the dielectric loss tangent value becomes large, and cracks are likely to occur due to heat generation. Corrosion resistance when used as a member for semiconductor and liquid crystal manufacturing equipment There is a risk that the lifespan is reduced due to the decrease in the life.

It is preferable that the density of the front surface is 3.90 g / cm ³ or more, thereby reducing the pore near the surface, for example, in the case where the plasma surface of the sintered body is irradiated, of the sintered body It is possible to suppress voids existing at the grain boundaries and improve plasma resistance.

  Here, the difference between the density near the surface and the internal density is the difference between the density of the sample cut from the vicinity of the surface of the sintered body and the density of the sample cut from the inside of the sintered body as shown in FIG. That is. The present invention is particularly effective in the case of a thick aluminum oxide sintered body having a thickness of 20 mm or more. Here, the density means an apparent density, and the measuring method is Archimedes method.

Furthermore, the aluminum oxide sintered body of the present invention preferably has a dielectric loss tangent value of 10 × 10 ⁻⁴ or less.

Thereby, the permeability of microwaves can be controlled better, and the occurrence of cracks can be suppressed well. On the other hand, if it exceeds 10 × 10 ⁻⁴ , microwaves are absorbed and cracks due to heat generation are likely to occur, and when used as a member for a semiconductor / liquid crystal manufacturing apparatus, the transmittance decreases due to heat generation. May cause damage.

  Here, the dielectric loss tangent in the present invention is a value measured at a frequency of 1 MHz by the bridge circuit method.

Here, the dielectric loss tangent in the present invention is 10 × 10 ⁻⁴ or less when the dielectric loss tangent of the aluminum oxide sintered body in the high frequency region (10 to 1000 MHz) is measured by a high frequency current voltage method, and is a microwave. It also means that the dielectric loss tangent of the aluminum oxide sintered body in the region (1 to 5 GHz) is 10 × 10 ⁻⁴ or less when measured by the cavity resonator method.

  The aluminum oxide sintered body of the present invention preferably has an aluminum oxide content of 99.2% by weight or more.

  This is because a higher aluminum oxide content is more suitably used in plasma resistance and chemical resistance. However, the higher the aluminum oxide purity, the greater the influence of trace impurities on the sintering process, and phosphorus It becomes easy to inhibit uniform grain growth. More preferably, the content of aluminum oxide is 99.5% by weight or more.

  The aluminum oxide sintered body of the present invention preferably contains magnesium oxide in a range of 0.05% by weight or more and has an average crystal grain size of 10 μm or less. That is, since magnesium oxide has an effect of suppressing grain growth, a dense sintered body with few voids can be obtained and the mechanical strength can be kept high. In addition, it is possible to prevent the dielectric loss tangent from being lowered due to voids and to satisfactorily suppress the generation of cracks due to heat generation of the aluminum oxide sintered body.

  Therefore, it is preferable to contain magnesium oxide as a minor component other than aluminum oxide in the sintering process of aluminum oxide. In addition, when the content of magnesium oxide exceeds 0.5% by weight, the chemical resistance and plasma resistance are adversely affected, so the upper limit is more preferably 0.5% by weight or less. At the same time, high mechanical strength can be obtained by setting the average crystal grain size of the aluminum oxide sintered body to 10 μm or less. When the phosphorus content exceeds 0.0025 parts by weight, grain growth near the surface tends to be promoted, and the average crystal grain size tends to increase. On the other hand, if it exceeds 10 μm, the wear resistance and chemical resistance are lowered, which is not preferable as a member for a semiconductor manufacturing apparatus, a member for a liquid crystal manufacturing apparatus, or a member for a general industrial machine. More preferably, it is 8 μm or less.

  Next, the manufacturing method of the aluminum oxide sintered body of this invention is demonstrated.

  First, for mixing and grinding the aluminum oxide powder having a low phosphorus content and subcomponents other than aluminum oxide, a ball mill or a high-speed stirring mill is generally used.

  Usually, 0.003 to 0.005 parts by weight of phosphorus is contained in the aluminum oxide powder. In general, the aluminum oxide obtained by the Bayer method is mixed in a soda removal step for converting to low soda aluminum oxide. By limiting the amount of phosphorus contained in the additive used for the soda removal, the phosphorus content contained in the resulting low soda aluminum oxide can be controlled. In the present invention, in order to make the content of phosphorus in the aluminum oxide sintered body obtained as described above 0.0025 part by weight or less, the content of phosphorus in the aluminum oxide powder is previously 0.0025 wt. It is desirable to adjust to less than or equal to parts.

  In order to make the aluminum oxide content of the obtained aluminum oxide sintered body 99.2% by weight or more, at least one of magnesium oxide, calcium oxide and silicon oxide can be added as a sintering aid. Good.

  Moreover, in order to contain magnesium oxide in 0.05 weight% or more, other two components are adjusted.

  In the mixing and pulverization, wet pulverization is performed using a ball made of an aluminum oxide sintered body or a zirconia sintered body using water as a solvent to adjust to a predetermined particle size distribution. An organic binder such as PVA or acrylic resin is added to the obtained slurry according to the use, and then spray dried to form ceramic granules for molding by dry granulation.

  Next, the granules thus obtained are formed into a predetermined shape by press molding or the like, and further processed into a predetermined shape as necessary. This is a manufacturing method using dry press molding, but a predetermined shape may be obtained by a wet molding method such as slip casting.

  Finally, the obtained molded body can be fired at a temperature of 1500 ° C. to 1700 ° C. to obtain the aluminum oxide sintered body of the present invention.

  In order to set the average crystal grain size of the obtained aluminum oxide sintered body to 10 μm or less, magnesium oxide is contained in a range of 0.05% by weight or more as a sintering aid, and an appropriate firing temperature is set. Can be sintered.

  The aluminum oxide sintered body of the present invention thus obtained is used as a component for industrial machinery, and particularly preferably used as a large and thick member used in a semiconductor manufacturing apparatus or a liquid crystal manufacturing apparatus. Can do. The semiconductor manufacturing apparatus member in the present invention is a member for use in a semiconductor manufacturing process. For example, a nozzle, a shower head, an inner wall, a heat insulating material, a plasma trap, a dome, a susceptor, a stage, a chuck, a clamp ring, Refers to the focus ring, microwave introduction window, and piping. Moreover, the member for liquid crystal manufacturing apparatuses is a member for using in the manufacturing process of a liquid crystal, for example, an insulator, a flame | frame, etc. are said.

  Examples of the present invention will be described below.

Example 1
Add at least one of magnesium hydroxide, calcium carbonate, and silicon oxide and phosphorus as auxiliary components to the low-soda aluminum oxide powder, disperse it in water with a high-speed dispersion mill, make it into a slurry, and then spray dry to obtain a ceramic powder. It was. This ceramic powder was press-molded into a molded body having a diameter of 60 mm and a thickness of 60 mm at 1000 kg / cm ² and heated at 1650 ° C. for 2 hours to obtain an aluminum oxide sintered body.

  In order to compare the density of the inside of the sintered body thus obtained and the vicinity of the surface, cubes each having a side of 10 mm were cut out from the inside and the vicinity of the surface as shown in FIG. 1, and the sintering density was measured. .

Moreover, the surface of the obtained aluminum oxide sintered body is made into a mirror surface by lapping, and is set in a RIE (Reactive Ion Etching) apparatus and exposed to plasma in a Cl ₂ gas atmosphere for 2 hours. The etching rate per minute is calculated from the above, and is obtained as a relative comparison value when the etching rate of the aluminum oxide sintered body (aluminum oxide content 99% by weight) prepared as a reference sample is 1, and this relative comparison value is obtained. Samples with a <1 were considered excellent.

  The contents of aluminum oxide, magnesium oxide and phosphorus in the sintered body were determined by ICP emission spectroscopic analysis.

The results are shown in Table 1.

From Table 1, Sample No. In No. 1, the phosphorus content exceeded 0.0025 parts by weight, and the difference between the density in the vicinity of the surface of the sintered body and the internal density was 0.020 g / cm ³ , showing almost no difference. This is presumably because Sample 1 has a content of aluminum oxide of 99% by weight or less, and thus liquid phase sintering is the main component, so that the influence of phosphorus on the sintering process is reduced. However, the etching rate of Sample 1 was 1 Å / min or more, and the plasma resistance did not show excellent characteristics.

Sample No. In Nos. 2-6 and 8-10, sample no. Compared with 7, the density difference in the vicinity of the surface of the sintered body and the internal density are both 0.05 g / cm ³ or less and the etching rate is 1 kg / min or less, which is excellent. In particular, when the phosphorus content is 0.0020 parts by weight or less, the density difference between the vicinity of the surface and the inside is 0.035 g / cm ³ or less, and when the phosphorus content is low, grain growth in the sintering process is caused. It can be seen that a uniform sintered body can be obtained without obstruction.

(Example 2)
Next, to the same aluminum oxide powder as in Example 1, at least one of magnesium hydroxide, calcium carbonate, and silicon oxide and phosphorus are added as subcomponents, and an aluminum oxide sintered body is obtained in the same manner as in Example 1. Got.

  Next, as in Example 1, the density in the vicinity of the surface of the sintered body, the internal density, the etching rate, and the dielectric loss tangent were measured.

The results are shown in Table 2.

From Table 2, Sample No. Nos. 11 and 12 have a phosphorus content of 0.0025 parts by weight or less, but the density difference between the vicinity of the surface and the inside is 0.05 g / cm ³ , and a uniform sintered body is obtained. The value is 10 × 10 ⁻⁴ or less, and good results are obtained. The etching rate has excellent characteristics of Å / min or less. On the other hand, sample No. No. 13 has a phosphorus content of 0.0030 parts by weight. The density difference between the vicinity of the surface and the inside was as large as 0.066 g / cm ^3, and the value of the dielectric loss tangent was 10 × 10 ⁻⁴ or more. The etching rate was 1.78 Å / min, which was a bad result. Sample No. Nos. 16 and 19 are samples in which the aluminum oxide content is 99.20 wt% and 99.60 wt%, respectively, and the phosphorus content exceeds 0.0025 parts by weight. In either case, the dielectric loss tangent was 10 × 10 ⁻⁴ or more and the etching rate was 1 Å / min or more as compared with the sample having a phosphorus content of 0.0025 parts by weight. Sample No. No. 20 has a phosphorus content of as low as 0.0014 parts by weight, and has excellent characteristics such as a density difference between the vicinity of the surface and the inside, a dielectric loss tangent, and an etching rate. It shows that the influence of phosphorus content on sintering increases as the purity of aluminum oxide increases.

(Example 3)
Next, an aluminum oxide sintered body was obtained in the same manner as in Examples 1 and 2. Using the obtained sintered body, the density in the vicinity of the surface of the sintered body, the internal density, the etching rate, the four-point bending strength, and the average crystal grain size were measured.

  Here, the average crystal grain size was measured by image analysis (Luzex).

The above results are shown in Table 3.

From Table 3, Sample No. In Nos. 27 and 28, the content of magnesium oxide in the sintered body is 0.05% by weight or more, the balance is calcia and silica, and the aluminum oxide purity is 99.00% by weight. The density difference between the vicinity of the surface and the inside is 0.05 g / cm ³ or less, and a uniform sintered body is obtained. The etching rate has excellent characteristics of Å / min or less. Further, the average particle diameter is 10 μm or less, and the four-point bending strength is 350 MPa or more, which indicates that the aluminum oxide sintered body for structural members has sufficient performance. On the other hand, sample No. In No. 26, the content of magnesium oxide is 0, the balance is calcia and silica, and the purity of aluminum oxide is 99.00% by weight. The density difference between the vicinity of the surface and the inside was 0.05 g / cm ³ , and a uniform sintered body was obtained. However, the average particle diameter was 10 μm or more, and the 4-point bending strength was as weak as 295 MPa. The value of dielectric loss tangent is 10 × 10 ⁻⁴ or less, and good results are obtained. The etching rate exceeded 1 kg / min or less, and proper characteristics were not obtained.

Sample No. 30, 31, 33, 34, 36 and 37 all contain 0.05% by weight or more of magnesium oxide, and the purity of aluminum oxide is 99.20% by weight, 99.60% by weight and 99.75% by weight, respectively. Thus, the balance is a composition of calcia and silica. Each sample has a density difference of 0.05 g / cm ³ or less between the vicinity of the surface and the inside, and a uniform sintered body is obtained. Also, the etching rate has excellent characteristics of Å / min or less. Yes. Further, the average particle diameter is 10 μm or less, and the four-point bending strength is 350 MPa or more, which indicates that the aluminum oxide sintered body for structural members has sufficient performance. On the other hand, sample No. Nos. 29, 32, and 35 are composed of calcia and silica so that the purity of aluminum oxide is 99.20 wt%, 99.60 wt%, and 99.75 wt% without containing magnesium oxide. . The average particle diameter exceeded 10 μm, and the 4-point bending strength was 350 MPa or less, and appropriate characteristics could not be obtained.

  The present invention can be effectively used as a member for a semiconductor manufacturing apparatus, a member for a liquid crystal manufacturing apparatus, or another industrial machine member, for example, a crusher member, a pump member, or a sliding member.

It is a figure for demonstrating the density of the surface vicinity part and internal density in the aluminum oxide sintered body of this invention.

Claims (8)

An aluminum oxide sintered body comprising an aluminum oxide having a content of 99% by weight or more and at least one selected from magnesium oxide, calcium oxide and silicon oxide, comprising phosphorus , the aluminum oxide An aluminum oxide sintered body containing 0.0025 part by weight or less of phosphorus with respect to 100 parts by weight of the sintered body. The aluminum oxide sintered body according to claim 1, wherein a density difference inside the sintered body is 0.05 g / cm ³ or less. 3. The aluminum oxide sintered body according to claim 1, wherein the dielectric loss tangent is 10 × 10 ⁻⁴ or less.   The aluminum oxide sintered body according to any one of claims 1 to 3, wherein the aluminum oxide content is 99.2% by weight or more.   The aluminum oxide sintered body according to any one of claims 1 to 4, wherein the magnesium oxide is contained in an amount of 0.05% by weight or more and an average crystal grain size is 10 µm or less. Aluminum oxide sintered body according to claim 1, the density of the front surface is characterized in that it is 3.90 g / cm ³ or more.   A member for a semiconductor manufacturing apparatus, comprising the aluminum oxide sintered body according to any one of claims 1 to 6.   A member for a liquid crystal manufacturing apparatus, comprising the aluminum oxide sintered body according to any one of claims 1 to 6.

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