JP2006089358A - Aluminum oxide-based sintered compact, its manufacturing method, and semiconductor producing equipment using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum oxide-based sintered compact meeting the requirements to reduce its production cost and to keep its corrosion resistance, since the aluminum oxide-based sintered compact is a ceramic sintered compact used in a process to produce a semiconductor or a liquid crystal, and is strongly required to further reduce its production cost in recent years, and is also required to keep its corrosion resistance. <P>SOLUTION: The aluminum oxide-based sintered compact contains aluminum oxide as a principal component and contains, as subsidiary components, one or more kinds of compounds of Si, Mg, or Ca. An amorphous phase containing elements of Si, Al, Ca, and O is formed at the grain boundary between crystal grains constituting the sintered compact. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum oxide sintered body and a manufacturing method thereof, and further, an inner wall material (chamber), a microwave introduction window, a shower head, a focus ring, and a shield of a semiconductor manufacturing apparatus using the aluminum oxide sintered body. The present invention can be applied to members including a ring, a stage of a liquid crystal manufacturing apparatus, a mirror, a mask holder, a mask stage, a chuck, a reticle, and the like, particularly a large member having a thick part.

  Conventionally, an aluminum oxide sintered body has excellent thermal, mechanical, and chemical characteristics and is widely used in various technical fields.

  One of the fields of utilization is a member for a semiconductor / liquid crystal manufacturing apparatus. This member for semiconductor / liquid crystal manufacturing equipment is high because it comes into contact with halogen-based corrosive gases such as fluorine and chlorine that are highly reactive and used for etching and cleaning in the semiconductor / liquid crystal manufacturing process and their plasma. Not only is corrosion resistance required, but also high performance is required for electrical and mechanical properties such as dielectric loss and strength. In addition, the ceramic used in the position that satisfies the above-mentioned requirements and can be folded in terms of cost is the aluminum oxide sintered body.

  In recent years, the need for an aluminum oxide sintered body has further increased, and member supplier manufacturers have inevitably conducted various studies on how to manufacture them at a low cost.

  However, the aluminum oxide sintered body is a material that has already been researched, and there has been a problem that even if the manufacturing process and material concept are slightly revised, a great reduction in manufacturing cost cannot be expected.

  To solve this problem, the cost can be greatly reduced by lowering the firing temperature of the conventional aluminum oxide sintered body to reduce the firing cost, and further reducing the grinding resistance of the sintered body to reduce the processing cost. A way to do this is conceivable. In the aluminum oxide sintered body, in order to achieve a lower firing temperature and a lower grinding resistance while maintaining the conventional characteristics, particularly corrosion resistance, the grain boundaries and the like have been determined from various experiments. It has been found that the presence of the amorphous (glass) phase present in the film becomes a problem.

On the other hand, regarding the amorphous phase in the aluminum oxide sintered body as described above, it has been generally considered that its presence itself leads to a decrease in corrosion resistance from the viewpoint of corrosion resistance. However, if the elements present in the amorphous phase are controlled, the corrosion resistance does not decrease, and even a low-purity aluminum oxide sintered body is suitable as a member for semiconductor and liquid crystal manufacturing equipment that requires excellent corrosion resistance. It is supposed that it can be used for (refer patent document 1, 2).
JP-A-10-279349 JP 2000-302537 A

  In Patent Documents 1 and 2, the amorphous phase present at the grain boundaries of the aluminum oxide sintered body is controlled, and the corrosion resistance can be maintained even with low purity. However, it was possible to reduce the cost of the member as much as the purity of the raw material was reduced, but it was insignificant, and eventually the firing atmosphere had to be a nitrogen atmosphere, so the cost reduction of the raw material would be offset. In addition, the manufacturing cost of the aluminum oxide sintered body could not be reduced.

  In addition, the aluminum oxide sintered bodies described in Patent Documents 1 and 2 have not been improved at all in terms of grindability, which is considered to contribute to a reduction in manufacturing cost, and there has been no cost advantage.

  In view of the above problems, the present invention is a sintered body containing aluminum oxide as a main component and any one or more of Si, Mg, and Ca as subcomponents, and crystal grains constituting the sintered body The aluminum oxide sintered body is characterized in that an amorphous phase containing Si, Al, Ca and O elements is formed at the grain boundaries.

  The grain boundary is a triple point of three crystal grains.

  Further, the maximum width of the amorphous phase existing between two crystal grains in the grain boundary is 1 μm or less.

  Further, the maximum width of the amorphous phase present at the triple point of the three crystal grains in the grain boundary is 5 μm or less.

  Moreover, it is an aluminum oxide sintered body containing 98% by mass or more of aluminum oxide and 2% by mass or less of subcomponents.

Further, the sub-component is less than 1 wt% of Si in terms of SiO _2, 0.2 wt% of Mg in terms of MgO below is characterized in that not more than 0.8 wt% of Ca in terms of CaO.

  Moreover, it is an aluminum oxide sintered body having an average crystal grain size of 3 to 50 μm.

Moreover, it is an aluminum oxide sintered body containing Na of 1000 ppm or less in terms of Na ₂ O and Fe of 300 ppm or less in terms of Fe ₂ O ₃ .

  Further, the pore occupation area ratio (void ratio) on the surface of the sintered body is 3% or less.

  Moreover, as a manufacturing method of the aluminum oxide sintered body of the present invention, a step of obtaining a primary raw material powder of aluminum oxide by blending 0.1 to 0.9 μm particles and 1 to 10 μm particles, and 2 μm or less A step of adding a sintering auxiliary agent together with a binder to the primary raw material powder, mixing and granulating to obtain a secondary raw material powder, and subjecting the obtained secondary raw material powder to a powder press molding method or an isostatic pressing method. A step of obtaining a green body by molding, a step of baking the green body at a firing temperature of 1500 to 1600 ° C. to obtain a sintered body, and grinding the sintered body with a grinding resistance value of 400 N or less. It is characterized by using a process.

  Further, the α crystal particle diameter of the primary raw material powder is set to 0.5 to 2 μm.

  Further, the sintering aid is characterized by being made of any one of Si and Ca.

  Moreover, the aluminum oxide sintered body is used as a corrosion-resistant member.

  The aluminum oxide sintered body of the present invention is a sintered body containing aluminum oxide as a main component and any one or more compounds of Si, Mg, and Ca elements as subcomponents. Particles constituting an aluminum oxide sintered body by the action of Si and Ca elements in the amorphous phase by forming an amorphous phase containing Si, Al, Ca and O elements at the grain boundaries of the crystal grains Therefore, it is possible to make the crystal grain size of the sintered body large and easy to scrape. Therefore, the processing man-hour at the time of grinding can be reduced, and processing costs can be significantly reduced. In addition, since Al element is contained in the amorphous phase, it is possible to obtain corrosion resistance equal to or higher than the conventional one.

  Moreover, the aluminum oxide sintered body of the present invention has a maximum width of the amorphous phase existing between two particles of 1 μm or less, and a maximum width of the amorphous phase present at the triple point between the three particles of 5 μm. For example, even when used as a member for a semiconductor or liquid crystal manufacturing apparatus, for example, the area of the amorphous phase exposed to corrosive gases and their plasma can be reduced, and its corrosion resistance is equal to or higher than the conventional one. It becomes possible to do.

  Furthermore, the aluminum oxide sintered body of the present invention is characterized by containing aluminum oxide in an amount of 98% by mass or more and subcomponents of 2% by mass or less, and each of Si, Mg, and Ca as subcomponents other than alumina. In order to produce a liquid phase at a lower temperature by setting the content ratio to 1% by mass or less, 0.2% by mass or less, and 0.8% by mass or less in terms of oxide, sintering is performed at a lower temperature than before. The firing cost can be reduced.

  In addition, since the aluminum oxide sintered body of the present invention has an average crystal grain size of 3 to 50 μm and has a larger average crystal grain size than conventional ones, in ceramics that are ground in the form of particle dropout. Has good grindability and can greatly reduce grinding costs.

Moreover, the aluminum oxide sintered body of the present invention is used as a member for a semiconductor or liquid crystal manufacturing apparatus by setting Na to 1000 ppm or less in terms of Na ₂ O and Fe to 300 ppm or less in terms of Fe ₂ O _3. In such a case, the content of Na and Fe, which can be the main cause of the particles, is small, so that the generation of particles can be suppressed as much as possible.

  Moreover, when the aluminum oxide sintered body of the present invention is used as a member for a semiconductor or liquid crystal manufacturing apparatus by setting the pore occupation area ratio (void ratio) of the sintered body surface to 3% or less, It is possible to reduce the contact surface area with fluorine-based or chlorine-based corrosive gas and its plasma used in the semiconductor manufacturing process, or etching liquid used in the liquid crystal manufacturing process, and to improve the corrosion resistance of the members It becomes possible.

  Moreover, as a manufacturing method of the aluminum oxide sintered body of the present invention, a step of obtaining a primary raw material powder of aluminum oxide by blending 0.1 to 0.9 μm particles and 1 to 10 μm particles, and 2 μm or less A step of adding a sintering aid to the primary raw material powder together with a binder, mixing and granulating to obtain a secondary raw material powder, and using the obtained secondary raw material powder by a powder press molding method or an isostatic pressing method A step of obtaining a molded body by molding, a step of firing the molded body at a firing temperature of 1500 to 1600 ° C. to obtain a sintered body, and a step of grinding the sintered body with a grinding resistance value of 400 N or less By mixing coarse powder and fine powder, the specific surface area is increased and the filling rate is increased by increasing the particle size difference compared to the blending of fine particles alone or between fine particles. Can improve grindability That.

  Further, as a method for producing the aluminum oxide sintered body of the present invention, it is necessary to pulverize the powder for a long time by using a relatively small primary material having an α crystal particle diameter of 0.5 to 2 μm. Therefore, the pulverization cost can be reduced.

  Moreover, as a manufacturing method of the aluminum oxide sintered body of the present invention, the sintering aid is made of any one of Si, Ca, and Mg, so that Si having a low melting point and Ca having a grain growth promoting action are added. In the case of promoting grain growth or adding both SiO and CaO as binders, it has not only made it possible to produce many common materials and calcination in the low temperature range, but also has a high practical value. A sintered body can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  The corrosion-resistant member of the present invention is a sintered body containing aluminum oxide as a main component and any one or more compounds of Si, Mg, and Ca elements as subcomponents. An amorphous phase containing Si, Al, Ca, and O elements is formed at the grain boundary, and can be suitably used as a semiconductor or liquid crystal manufacturing apparatus.

The semiconductor and liquid crystal manufacturing apparatuses include fluorine-based gases such as SF ₆ , CF ₄ , CH 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. Or halogen-based corrosive gases such as bromine-based gases such as Br ₂ , HBr, and BBr ₃ are used, and these gases are used for members for semiconductor and liquid crystal manufacturing devices in order to generate and use those plasmas. And high corrosion resistance to the plasma.

  Here, the amorphous phase is shown in FIG. 1 as a schematic cross-sectional view of the aluminum oxide sintered body of the present invention, and the position of the grain boundary of the two crystal particles 2 of the aluminum oxide sintered body (FIG. 1). (A)) or a triple point between three crystal grains (FIG. 1 (b)).

  In the present invention, the structure in which the amorphous phase 1 exists at the position of the grain boundary or triple point between the crystal grains in this way promotes sintering by creating a liquid phase at a low temperature and a high density in a low temperature range. It becomes a sintered body. Therefore, the firing time is shorter than in the prior art, and the firing can be performed in an air atmosphere, so that no gas for adjusting the atmosphere is required, and in particular, the manufacturing cost for the firing process can be greatly reduced.

  In the present invention, it can be said that the amorphous phase 1 includes Si, Al, Ca, and O elements. If such an element is contained in the amorphous phase 1, it becomes possible to promote grain growth of crystal grains constituting the aluminum oxide sintered body by the action of Si and Ca, and to improve grindability, Further, due to the action of the Al element, even in the amorphous phase 1, it becomes possible to maintain the corrosion resistance against the corrosive gas like the sintered body.

Here, the grain growth is promoted by adding Si and Ca to the amorphous phase 1 because Si and Ca elements such as SiO ₂ and CaO added to form the amorphous phase 1 are added. This is because the contained compound melts at a low temperature to form a liquid phase that activates the surface of each crystal particle. In particular, since CaO melts in the vicinity of 1400 ° C., if the content ratio of CaO is increased, heat treatment can be performed at a lower temperature, and an aluminum oxide sintered body having larger crystals after heat treatment can be obtained. By promoting grain growth and enlarging the crystal grain size in this way, in ceramics that can be processed in the form of crystal grains falling off, the grindability is improved and the grinding cost is greatly reduced compared to the past. It becomes possible to do.

  Further, when the amorphous phase 1 contains an Al element having high corrosion resistance, when the aluminum oxide sintered body of the present invention is used as a member for a semiconductor or liquid crystal manufacturing apparatus, corrosive gases and their It can be set as the member which has sufficient corrosion resistance with respect to plasma.

  In addition, as a content rate of Si, Al, Ca, and O element contained in the amorphous phase 1, Si is 15 to 20 mol%, Al is 12 to 16 mol%, Ca is 3 to 7 mol%, and O is It is good to set it in the range of 51-65 mol%. The ratio is based on a value calculated by a quantitative method such as a thin film approximation method from a spectrum detected by using an energy dispersive X-ray spectroscopic analyzer and reducing the X-ray irradiation spot diameter to 1 to 50 nm.

  Further, the size of the amorphous phase 1 in the aluminum oxide sintered body is schematically shown in FIG. 1 by observing a cross section of the sintered body at a high magnification with a transmission electron microscope or the like. It is possible to obtain a cross-sectional photograph of the sintered body, and from this photograph, the size of the amorphous phase at the grain boundary or triple point is measured as the width of the grain boundary or triple point.

  The maximum width of the grain boundary or triple-point amorphous phase is 1 μm or less as the grain boundary and 5 μm or less as the triple point. Here, when the maximum width of the grain boundary or triple point is set to 1 μm or less and 5 μm or less, respectively, the aluminum oxide sintered body is used as a member for a semiconductor or a liquid crystal manufacturing apparatus, for example. In this case, the area of the amorphous phase 1 exposed to the corrosive gases and their plasmas increases, and corrosion progresses from that portion and the corrosion resistance of the entire member decreases.

  In the present invention, by adding Al element to the amorphous phase, the corrosion resistance of the amorphous phase 1 is improved. However, if it is outside the above range, it is more corrosive than the particles constituting the sintered body. Corrosion resistance tends to be corroded by reactive gases and plasmas. More preferably, the maximum width of the amorphous phase at each of the grain boundaries and triple points is 0.5 μm or less and 3 μm or less, respectively.

  Moreover, the aluminum oxide sintered body of the present invention is preferably composed of 98% by mass or more of aluminum oxide and 2% by mass or less of other subcomponents. This is because if the aluminum oxide is in a range of less than 98% by mass, it becomes a sintered body that is remarkably inferior in corrosion resistance when used as a member for a semiconductor or liquid crystal manufacturing apparatus. This is because, of course, the mechanical properties, particularly strength and hardness of the aluminum oxide sintered body are lowered.

Furthermore, as the auxiliary component, 1% by mass of Si in terms of SiO ₂ or less, 0.2 mass% of Mg in terms of MgO less, had better be a ratio of 0.8 mass% or less in terms of CaO to Ca. The above-mentioned proportions of Si, Mg, and Ca are higher than that, and when the aluminum oxide sintered body of the present invention is used as a semiconductor or liquid crystal manufacturing apparatus, corrosive gas or its This is because the corrosion resistance against plasma is reduced.

  Moreover, when Si, Mg, and Ca are each contained alone, the aluminum oxide sintered body is difficult to increase in density, and therefore, contained as any combination of Si—Mg, Si—Ca, and Mg—Ca. It is more preferable that the shape is made. In this case, since the generation of the liquid phase starts near 1200 ° C. in the combination of Si—Ca, the sinterability is improved in the aluminum oxide sintered body of the present invention, which is preferable. In other combinations of Si—Mg, generation of a liquid phase is started around 1500 ° C., and in the case of Ca—Mg, around 2400 ° C. In summary, Si—Ca is more suitable for lowering the firing temperature, and it can be said that sinterability can be improved in the order of Si—Mg and Ca—Mg.

  The aluminum oxide sintered body of the present invention preferably has an average crystal grain size of 3 to 50 μm. When the average crystal grain size is smaller than 3 μm, the mechanical characteristics are remarkably improved, but the grindability is remarkably deteriorated, and it becomes difficult to process the sintered body into various shapes. When the average crystal grain size is larger than 50 μm, the grindability is remarkably improved because the grain size is large and the grinding amount is increased at one time. The strength and hardness required for the structural member cannot be satisfied. The average crystal grain size is obtained by mirror-processing and etching the cross section of the sintered body, taking a crystal photograph at a predetermined magnification using an electron microscope, measuring the crystal grain diameter within a predetermined range of the photograph, and calculating an average value thereof. Is obtained by calculating.

Furthermore, the aluminum oxide sintered body of the present invention preferably has a Na content of 1000 ppm or less in terms of Na ₂ O and a Fe content of 300 ppm or less in terms of Fe ₂ O ₃ . This makes it possible to minimize the generation of Na and Fe compounds, which are the main cause of particles in the semiconductor and liquid crystal manufacturing processes.

  The contents of Na and Fe can be measured by quantitative analysis with an ICP emission spectroscopic analyzer. Specifically, a portion of the sintered body is finely pulverized, and a small amount of this is mixed with a chemical solution such as sulfuric acid, nitric acid, hydrofluoric acid, etc., and then subjected to pressure acid decomposition, and this solution is heated to treat white smoke. And a desired element is designated and quantitative analysis is performed with an ICP emission spectroscopic analyzer.

  In addition, the aluminum oxide sintered body of the present invention has a porosity occupied area ratio (void ratio) of 3% or less on the surface of the sintered body, so that corrosive gases used in semiconductor and liquid crystal manufacturing processes and their The surface area exposed to plasma can be reduced, and a sintered body having good corrosion resistance can be obtained. Note that the pore occupation area ratio is obtained by mirror-processing the cross section of the sintered body and calculating the ratio of the black part (= void part) with several high-magnification photographs using an image analyzer.

  Moreover, in the aluminum oxide sintered body of the present invention, it is preferable to take a distribution form of crystal grain size in which crystals of 10 μm or more account for 50% or more. As a result, since a large amount of relatively large crystal grains are contained, the grindability is greatly improved, and as a result, the grinding resistance value can be kept low. And the number of processes can be reduced as much as possible, and the manufacturing cost can be greatly reduced.

The density of the aluminum oxide sintered body of the present invention is preferably 3.8 g / cm ³ . When the density is lower than 3.8 g / cm ^{3, the} number of pores existing on the surface of the sintered body increases. Therefore, when used as a member for a semiconductor or liquid crystal manufacturing apparatus, the surface area exposed to corrosive gas or plasma thereof is low. Increases and decreases corrosion resistance.

  Further, regarding the mechanical properties, it is preferable that the strength (three-point bending) is 200 MPa or more and the Young's modulus is 300 GPa or more. These mechanical characteristics are values that are commonly required for members used for semiconductor and liquid crystal manufacturing apparatuses. Below this, even if they exhibit high corrosion resistance, they are difficult to apply.

  In addition, the said density is calculated | required by the Archimedes method, About the said intensity | strength and Young's modulus, the value measured based on JISR1601-1995 is shown.

  Next, the manufacturing method of the aluminum oxide sintered body of the present invention will be described in detail.

  The method for producing an aluminum oxide sintered body according to the present invention comprises a step of obtaining 0.1 to 0.9 μm particles and 1 to 10 μm particles to obtain a primary raw material powder of aluminum oxide, and a sintering of 2 μm or less. A step of adding a binder together with a binder to the primary raw material powder, mixing and granulating to obtain a secondary raw material powder, and using the obtained secondary raw material powder by a powder press molding method or an isostatic pressing method A step of molding to obtain a molded body, a step of firing the molded body at a firing temperature of 1500 to 1600 ° C. to obtain a sintered body, and a step of grinding the sintered body with a grinding resistance value of 400 N or less, It is characterized by comprising.

  Here, the 0.1 to 0.9 μm particles and the 1 to 10 μm particles are blended with a small particle of 0.1 to 0.9 μm in a gap between relatively large particles of 1 to 10 μm. In order to increase the density of the molded body after the molded body, it is possible to improve the handleability of the molded body, and it is also possible to increase the density of the sintered body. When mixing the particle size, the mixture is stirred using a commercially available dry stirring and mixing device.

  Then, after mixing the primary particle powder of aluminum oxide mixed with the particle size together with a sintering aid of 2 μm or less and commercially available various binders using a stirring and mixing device used at the time of particle size mixing, a spray dryer device is used. The secondary raw material is obtained by granulation by all spray granulation methods.

Here, the particle size of the sintering aid is set to 2 μm or less because the particle size of the sintering aid is reduced to improve the dispersibility in the aluminum oxide raw material powder, and thereby the sintered body after firing. This is because the amorphous phase 1 is formed at the grain boundaries or triple points throughout, more preferably 1 μm or less. Further, as the sintering aid, commercially available silicon oxide (SiO ₂ ), calcium oxide (CaO), and magnesium oxide (MgO) are pulverized using a pulverizing means such as a vibration mill or a ball mill until a desired particle size is obtained. It is good to use.

  And the said secondary raw material powder is shape | molded by the powder press molding method or an isostatic pressing method (rubber press), and a molded object is obtained. In the case of using any of the powder press molding method and the isostatic press molding method, cutting may be further performed so as to obtain a desired shape after molding.

  Next, the compact is fired at a firing temperature of 1500 to 1600 ° C. to obtain a sintered body. Usually, a high-purity alumina sintered body exceeding 95% is fired in a high temperature range of about 1600 ° C., but the aluminum oxide sintered body of the present invention is 1500 to promote grain growth at a lower temperature. It can be fired at ˜1600 ° C. at a relatively low temperature compared to the prior art.

  In this way, the aluminum oxide sintered body of the present invention is obtained, but in order to obtain a predetermined shape, the sintered body obtained through the previous manufacturing process is finally subjected to grinding, to a predetermined shape, It is necessary to finish within the dimensions. In the present invention, grinding is performed with the grinding resistance value generated during the grinding process being 400 N or less. By processing with such a low grinding resistance value, the amount of grinding can be increased, and the grinding process is performed. Not only can the time be shortened, but the number of processing steps can be greatly reduced, so that the total manufacturing cost can be greatly reduced.

  Here, the grinding resistance value refers to the friction force generated between the workpiece and the electrodeposition diamond when drilling is performed by the electrodeposition diamond perpendicularly toward the workpiece using a machining center device. Measured with a type dynamometer. More specifically, the tip outer diameter 3 attached to the tip of the machining center device while spraying a grinding fluid at a temperature of about 20 ° C. on the workpiece at a pressure of 5 to 30 MPa at an angle of 10 to 90 ° with respect to the machining surface. 10 to 20 holes are drilled into the workpiece at a depth of 10 mm or less at a rotation speed of 3000 to 8000 rpm / min and a vertical feed rate of 10 to 50 mm / min by a 10 mm electrodeposition diamond. At this time, the frictional force generated between the workpiece and the diamond when the final drilling is performed is measured with a piezoelectric dynamometer. In the present invention, since the measured value at this time can be processed with a relatively low grinding resistance value of 400 N or less, it is possible to increase the amount of processing at one time, thereby reducing the number of processing steps and the processing time is short. Compared to other materials, the number of processing processes per unit time is large, which makes it possible to greatly reduce the processing cost.

  The piezoelectric type dynamometer may be a commercially available one. In particular, by using a quartz crystal as the piezoelectric element, it is possible to suppress numerical variation during grinding resistance measurement.

  Next, an example in which the aluminum oxide sintered body of the present invention is used as a processing container member of an inductively coupled plasma etching apparatus which is a semiconductor manufacturing apparatus is shown in FIG.

  FIG. 2 is a schematic cross-sectional view showing the inductively coupled plasma etching apparatus 10, and the reference numeral 11 in the figure is the processing container 11 of the present invention. The processing container 11 has a dome shape, and has a rough surface portion 12 on the inner wall surface. A metal lower chamber 13 is provided below the processing container 11 so as to be in close contact with the processing container 11. Has been. A support table 14 is disposed in the upper portion of the lower chamber 13, and an electrostatic chuck 15 is provided on the support table 14. A semiconductor wafer 16 is placed on the electrostatic chuck 15. A direct current power source is connected to the electrode of the electrostatic chuck 15, thereby electrostatically adsorbing the semiconductor wafer 16.

  An RF power source is connected to the support table 14. On the other hand, a vacuum pump 19 is connected to the bottom of the lower chamber 13 so that the inside of the chamber 13 can be evacuated.

A gas supply nozzle 17 for supplying an etching gas such as CF ₄ gas is provided above the semiconductor wafer 16 above the lower chamber 13. An induction coil 18 is provided around the processing container 1, and a high frequency of 400 kHz, for example, is applied to the induction coil 18 from an RF power source.

In such an etching apparatus 10, the inside of the chamber 13 is evacuated to a predetermined degree of vacuum by the vacuum pump 19, the semiconductor wafer 16 is electrostatically adsorbed by the electrostatic chuck 15, and then, for example, CF ₄ gas is used as an etching gas from the nozzle 17. By supplying power to the induction coil 18 from the RF power supply, etching gas plasma is formed in the upper portion of the semiconductor wafer 16, and the semiconductor wafer 16 is etched into a predetermined pattern.

  Note that the anisotropy of etching can be increased by supplying power to the support table 15 from a high-frequency power source.

During such an etching process, the inner surface of the processing vessel 11 is corroded by CF ₄ gas or plasma thereof, and a fluoride film or the like is attached thereto.

  However, since the processing container 11 is composed of the above-described aluminum oxide sintered body of the present invention, the corrosion resistance against plasma is high, and deposits are not easily dropped due to the influence of the rough surface portion 12 formed on the surface.

  The aluminum oxide sintered body of the present invention is not limited to the processing container of the semiconductor manufacturing apparatus as shown in FIG. 2, but can be used for members such as a chamber, a microwave introduction window, a shower head, a focus ring, and a shield ring. is there.

  In addition, the liquid crystal manufacturing apparatus has almost the same structure as that of the semiconductor manufacturing apparatus, but the size of the processed product is larger than that of the semiconductor, and accordingly, the size of the liquid crystal manufacturing apparatus member is also large. Become.

  The aluminum oxide sintered body of the present invention can also be applied as a member for a liquid crystal manufacturing apparatus having an increased size, and is rather suitable for use as a member for a liquid crystal manufacturing apparatus because it can be baked at low temperatures and easily processed. . Examples of the liquid crystal manufacturing apparatus member used include a stage, a mirror, a mask holder, a mask stage, a chuck, and a reticle.

  As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that it can apply also to what was variously improved and changed if it is a range which does not deviate from the scope of the present invention.

  Examples of the present invention will be described below.

  First, an aluminum oxide powder having a purity of 99%, a particle size of 1 μm at a ratio of 90 mass%, and a particle size of 0.6 μm at a ratio of 10 mass% by stirring and mixing with a dry stirring mixer is prepared.

Thereafter, to 98% by mass of the powder, commercially available SiO ₂ , MgO, and CaO purified powders as a sintering aid are added and mixed at a ratio as shown in Table 1 so that the total amount becomes 2% by mass. . It is set as the mixed powder used as the origin of 1-15.

  Then, 0.1 to 1% by mass of PVA as a binder and a predetermined amount of water as a solvent are added to each mixed powder, and each sample is mixed in a ball mill for 1 hour to form a slurry. After granulating into a secondary raw material powder, the granulated powder is put into a rubber mold and molded with an isostatic press machine, and then a molded body having a diameter of 75 mm and a thickness of 12.5 mm is formed by cutting. Make it.

  Thereafter, each sample was fired at a firing temperature of 1550 ° C. in an air atmosphere, whereby a sample No. having a size of φ60 mm × thickness 10 mm was obtained. 1-15 are obtained.

  Next, each surface of one side of the sample is mirror-finished, the surface is observed with a transmission electron microscope, and the amorphous phase portion existing at the grain boundary is irradiated with X-rays using an energy dispersive X-ray spectrometer. The elements present in the amorphous phase are confirmed from the reflection spectrum.

At the same time, the maximum width of the grain boundary was confirmed.

  Moreover, the same surface was observed with a metal microscope, a 200-fold enlarged structure photograph was taken, and the average crystal particle diameter was calculated from this photograph.

  Further, after confirming the elements in the amorphous phase, a machining center apparatus in which a tip-shaped φ5 mm electrodeposition diamond was attached to the opposite surface of the same sintered body, the rotational speed was 5000 rpm / min, and the vertical feed speed was 25 mm / min. With a piezoelectric type dynamometer (KISTLER-TYPE5019) manufactured by Kistler, in which the frictional force generated between the sample and the electrodeposited diamond was preliminarily attached to the machining center device. This was measured and used as a grinding resistance value.

  The electrodeposition diamond is replaced with a new one every time the grinding resistance of each sample is measured, and measurement variations due to the surface state of the electrodeposition diamond are eliminated.

  Moreover, the corrosion resistance with respect to corrosive gas and its plasma was also evaluated using the said sample.

  In the evaluation, each sample was set in a RIE (Reactive Ion Etching) apparatus, exposed to plasma in a fluorine-based gas atmosphere such as CF4, and the etching rate per minute was calculated from the weight loss before and after that.

  The sample is used after mirror finishing again before the corrosion resistance evaluation.

The test results are shown in Table 1.

From Table 1, sample No. For Nos. 1 to 3, SiO ₂ , MgO, and CaO were added alone as sintering aids, and since the sinterability was poor and the density was not high, the mechanical strength was extremely low. 1 and 2 were not able to measure each characteristic of cracking during processing.

  Sample No. Although No. 3 was processed, the corrosion resistance was low because the strength was low and the density was not sufficiently increased.

  Sample No. Nos. 4, 11 and 12 show that the Ca is not contained in the amorphous phase and the grain growth is not promoted so much, so that it shows a grinding resistance value of 400 N or more, and such a high grinding resistance value seems to be considered. The processing cost cannot be reduced.

  Furthermore, sample no. 6, 13 and 15 all have poor sinterability and cannot be sufficiently densified at a temperature of 1550 ° C., so the mechanical strength is low. Similar to 1 and 2, breakage occurred during sample processing, and each characteristic evaluation could not be performed.

  Compared to this, sample No. within the scope of the present invention. 5, 7, 8, 9, 10, and 14 are all sufficiently densified, the grinding resistance value is as low as 400 N or less, the corrosion resistance is also good, and the firing cost and processing cost are reduced. It was confirmed that this was possible.

  Next, sample no. The processing vessel of the inductively coupled plasma etching apparatus shown in FIG.

  The processing container has an outer diameter of 1.5 m and an average wall thickness of 10 mm.

  As a result, what was conventionally obtained only at a temperature of 1650 ° C. can be obtained at a low firing temperature of 1550 ° C. by using the aluminum oxide sintered body of the present invention. It was confirmed that the firing cost can be reduced.

  Furthermore, in the grinding process after firing, it was possible to carry out grinding with a processing amount more than twice the conventional amount, and the processing time was reduced to less than half, which confirmed that processing costs could be reduced. .

FIG. 1 is a schematic cross-sectional view of an aluminum oxide sintered body according to the present invention, in which FIG. 1 (a) is the position of a grain boundary of two crystal particles 2 of the aluminum oxide sintered body, and FIG. 1 (b) is three crystal particles. It is a schematic diagram which shows the position of the triple point in between. It is sectional drawing of the inductively coupled plasma etching apparatus which is a semiconductor manufacturing apparatus using the aluminum oxide sintered body of this invention as a process container member.

Explanation of symbols

1: amorphous phase 2: crystal particle 10: inductively coupled plasma etching apparatus 11: processing vessel 12: rough surface portion 13: chamber 14: support table 15: electrostatic chuck 16: semiconductor wafer 17: gas supply nozzle 18: induction Coil 19: Vacuum pump

Claims (14)

A sintered body containing aluminum oxide as a main component and any one or more compounds of Si, Mg, and Ca as subcomponents, wherein Si, Al, An aluminum oxide sintered body characterized in that an amorphous phase containing Ca and O elements is formed. The aluminum oxide sintered body according to claim 1, wherein the amorphous phase exists between two crystal grains. The aluminum oxide-based sintered body according to claim 2, wherein the maximum width of the amorphous phase existing between two crystal grains is 1 µm or less. The aluminum oxide sintered body according to claim 1, wherein the amorphous phase is present at a triple point of crystal grains. 5. The aluminum oxide sintered body according to claim 4, wherein the maximum width of the amorphous phase existing at the triple point of the crystal grains is 5 μm or less. The aluminum oxide sintered body according to any one of claims 1 to 5, wherein said aluminum oxide contains 98% by mass or more and subcomponents 2% by mass or less. The 1 wt% secondary component the Si in terms of SiO ₂ or less, 0.2 mass% of Mg in terms of MgO below, according to claim 6, characterized in that not more than 0.8 wt% of Ca in terms of CaO Aluminum oxide sintered body. The aluminum oxide sintered body according to any one of claims 1 to 7, wherein an average crystal grain size is 3 to 50 µm. The aluminum oxide sintered body according to any one of claims 1 to 8, wherein Na is contained in an amount of 1000 ppm or less in terms of Na ₂ O, and Fe is contained in an amount of 300 ppm or less in terms of Fe ₂ O ₃ . The aluminum oxide sintered body according to any one of claims 1 to 9, wherein a pore occupation area ratio (void ratio) on the surface of the sintered body is 3% or less. A method for producing an aluminum oxide sintered body according to any one of claims 1 to 10, wherein 0.1 to 0.9 µm particles and 1 to 10 µm particles are mixed to form a primary material for aluminum oxide. Obtaining a powder;
Adding a sintering aid of 2 μm or less to the primary raw material powder together with a binder, mixing and granulating to obtain a secondary raw material powder;
Molding the obtained secondary raw material powder using a powder press molding method or an isostatic pressing method to obtain a molded body,
Firing the molded body at a firing temperature of 1500 to 1600 ° C. to obtain a sintered body;
A method for producing an aluminum oxide sintered body comprising a step of grinding the sintered body with a grinding resistance value of 400 N or less. The method for producing an aluminum oxide sintered body according to claim 11, wherein the α crystal particle diameter of the primary raw material powder is 0.5 to 2 µm. The method for producing an aluminum oxide sintered body according to claim 11 or 12, wherein the sintering aid is composed of at least one of Si, Ca, and Mg. A semiconductor manufacturing apparatus using the aluminum oxide sintered body according to claim 1 as a corrosion-resistant member.

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