KR101268870B1 - Rare-earth oxide-alumina ceramics having excellent plasma erosion resistance and manufacturing method of the same - Google Patents

Abstract

According to the present invention, a part of Y is substituted with Gd in a Y ₃ Al ₅ O ₁₂ composition containing less rare earth metal, or a part of La is substituted with Y in a LaAl ₁₁ O ₁₈ composition to have excellent plasma resistance and superior phase stability. It relates to a rare earth oxide-alumina ceramic having a and a method for producing the same. According to the present invention, since secondary phases such as Al ₂ O ₃ do not exist or are contained very little, selective etching of Al ₂ O ₃ does not occur, there is little possibility of generation of contaminated particles, and thermal phase stability since it contains a garnet crystal phase. It has excellent phase stability and can be used as a heat shielding material because of its excellent mechanical properties at high temperatures.

Description

Rare-earth oxide-alumina ceramics having excellent plasma erosion resistance and manufacturing method of the same}

The present invention relates to a rare earth oxide-alumina-based ceramic and a method for manufacturing the same, and more particularly, in the Y ₃ Al ₅ O ₁₂ composition containing a relatively small rare earth metal, a part of Y is substituted with Gd, or LaAl ₁₁ O ₁₈ The present invention relates to a rare earth oxide-alumina ceramic having a phase stability while having a portion of La replaced by Y in the composition and having excellent plasma resistance, and a method of manufacturing the same.

As ultrafine line width is widely used in semiconductor manufacturing processes, the lifetime of surrounding materials is greatly reduced and contaminant particles are increased in the chamber where the plasma process is performed.

In general, the plasma process not only promotes chemically active radicals by generating radicals that are chemically active, but also releases cations dissociated by plasma at high energy into the surface of the material to promote the reaction and physically etch the material. Cause. Al ₂ O ₃ is typically used as a material having excellent plasma resistance, and in recent years, Y ₂ O ₃ having excellent plasma resistance has been adopted and widely used.

The reason why Y ₂ O ₃ shows better etching resistance than Al ₂ O ₃ in fluorine-based plasma is that the compound between yttrium (Y) and fluorine (F) has a high binding energy. In recent research, when aluminum-yttrium-based ceramics were exposed to fluorine-based plasma, fluorination of the specimen surface was greatly increased, and thus the removal rate of the fluorine-based compound was a major factor in determining the etching rate. In general, considering that the greater the heat of sublimation reaction, the lower the sputtering rate, the fluorine-based compound of yttrium (Y) is more slowly etched than aluminum (Al).

It is obvious that Y ₂ O ₃ is a material with excellent plasma resistance, but the supply and demand is irregular worldwide, and the price fluctuations are severe in recent years, increasing the difficulty of the industry. Therefore, research on materials that can replace Y ₂ O ₃ needs to be preceded. However, the characteristics of materials that can resist the semiconductor etching process have not yet been established, and thus, the development of materials that can be used in the semiconductor etching process is insufficient.

The problem to be solved by the present invention is that the rare earth element Gd which forms a solid solution in the crystal structure of Y ₃ Al ₅ O ₁₂ and exhibits excellent corrosion resistance against fluorine-based plasma is substituted for a portion of Y to have excellent plasma resistance The present invention provides a rare earth oxide-alumina ceramic having high phase stability and a method of manufacturing the same.

Another problem to be solved by the present invention is a rare earth element Y, which forms a solid solution in the crystal structure of LaAl ₁₁ O ₁₈ and exhibits excellent corrosion resistance to fluorine-based plasma, replaces part of La or the garnet crystal phase together with the LaAl ₁₁ O ₁₈ crystal phase. The present invention further provides a rare earth oxide-alumina ceramic having superior plasma properties and phase stability, and a method of manufacturing the same.

The present invention is a rare earth oxide-alumina-based ceramic having a composition of A ₃ Al ₅ O ₁₂ , wherein the A site is composed of Gd _x Y _1-x (0 <x≤0.8), and Gd and Y are atomically substituted with each other. It contains a garnet crystal phase that forms a solid solution having a solid structure, and the diffraction peak strength of the garnet structure I ₍₂₁₁₎ and GdAlO _{3 in} a rare earth oxide-alumina ceramic of (Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ composition The amount of corundum crystal phase when the relative amounts of the garnet crystal phase, the GdAlO ₃ crystal phase and the corundum crystal phase were measured from the diffraction peak intensity I ₍₁₁₀₎ of the structure and the diffraction peak intensity of the corundum structure ₍ I ₁₀₄₎ . A rare earth oxide-alumina ceramic having plasma characteristics is characterized by being less than or equal to 10% with respect to the total amount of the crystal phase.

In addition, the present invention is a rare earth oxide-alumina ceramic having a BAl ₁₁ O ₁₈ composition, wherein the B site is made of La _x Y _1-x (0 <x <1), and includes a LaAl ₁₁ O ₁₈ crystal phase and a garnet crystal phase. The present invention provides a rare earth oxide-alumina-based ceramic having plasma characteristics, wherein the etching rate with respect to the fluorine-based plasma is smaller than that of the LaAl ₁₁ O ₁₈ composition.

The rare earth oxide-alumina ceramic has a lower etching rate than quartz and sapphire under fluorine plasma etching conditions.

In the rare earth oxide-alumina ceramic having the A ₃ Al ₅ O ₁₂ composition, the A site is made of Gd _x Y _1-x (0 < _x ≦ 0.5), so that the etching rate of the fluorine plasma is Y ₃ Al ₅ O ₁₂ . It may be smaller than ceramic.

In the rare earth oxide-alumina-based ceramic having a (La _x Y _1-x ) Al ₁₁ O ₁₈ composition, I _{(104) in the} range of 0.8≤x <1 and the diffraction peak intensity of the corundum structure and the diffraction peak intensity of the garnet structure the amount of the I ₍₂₁₁₎ and, LaAl ₁₁ O nose from a diffraction peak intensity in I ₍₀₁₂₎ of ₁₈ reondeom crystal phase, garnet crystal phase and LaAl ₁₁ O ₁₈ as measured by the relative amount of the crystal phase co reondeom amount of the whole crystal of the crystal phase Less than or equal to 10%.

In addition, the present invention, in the method for producing a rare earth oxide-alumina ceramic of the A ₃ Al ₅ O ₁₂ composition, to achieve a (Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ (0 < _x ≤ 0.8) composition. Al ₂ O _3, Y ₂ O ₃ and Gd ₂ O ₃ by calculating the molar ratio of Al ₂ O ₃ powder, Y ₂ O ₃ powder and Gd ₂ O ₃ powder; and the Al ₂ O, which were weighed and mixed for _3, Preparation of Rare Earth Oxide-Alumina Ceramics with Plasma Resistance Characteristics comprising Molding a Mixture of Y ₂ O ₃ and Gd ₂ O ₃ to Closest Fill and Sintering the Molded Result at a Temperature of 1500-1800 ° C Provide a method.

In addition, the present invention, in the method for producing a rare earth oxide-alumina ceramic having a BAl ₁₁ O ₁₈ composition, Al ₂ O ₃ to achieve a (La _x Y _1-x ) Al ₁₁ O ₁₈ (0 <x <1) composition , Y ₂ O _3, and by calculating the molar ratio of La ₂ O ₃ Al ₂ O _3, powder, Y ₂ O ₃ powder, and La ₂ O; and the Al ₂ O, which were weighed and mixed for ₃ powder _3, Y ₂ O _It provides a method for producing a rare earth oxide-alumina ceramic having a plasma resistance characteristics comprising the step of molding the mixture of ₃ and La ₂ O ₃ to the closest filling and sintering the molded product at a temperature of 1500 ~ 1800 ℃ do.

The mixing uses a ball milling process, phosphoric acid is used in the ball milling process to disperse oxides, and the molding is preferably using a cold hydrostatic press.

In order to make the rare earth oxide-alumina ceramic of the A ₃ Al ₅ O ₁₂ composition smaller than the ceramic of the Y ₃ Al ₅ O ₁₂ composition in the etching rate with respect to the fluorine-based plasma, the A site has Gd _x Y _1-x (0 Al ₂ O ₃ powder, Y ₂ O ₃ powder and Gd ₂ O ₃ powder can be weighed and mixed by calculating the molar ratios of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ so that <x≤0.5). have.

B site is made of La _x Y _1-x (0.8 ≦ _x <1) so that the alumina (Al ₂ O ₃ ) crystal phase is not present or is very small in the rare earth oxide-alumina-based ceramic of BAl ₁₁ O ₁₈ composition. The molar ratios of fork Al ₂ O ₃ , Y ₂ O ₃ and La ₂ O ₃ can be calculated to weigh and mix Al ₂ O ₃ powder, Y ₂ O ₃ powder and La ₂ O ₃ powder.

According to the rare earth oxide-alumina ceramic having plasma characteristics according to the present invention, since the ionic radii of Y and Gd are similar, (Y · Gd) ₃ Al having phase stability without forming a secondary phase such as Al ₂ O ₃ It is possible to form a solid solution of ₅ O ₁₂ . The rare earth element Gd, which forms a solid solution in the crystal structure of Y ₃ Al ₅ O ₁₂ and exhibits excellent corrosion resistance against fluorine-based plasma, is substituted for a portion of Y to have excellent plasma resistance and phase stability.

In addition, according to the rare earth oxide-alumina ceramic having plasma characteristics according to the present invention, Y is a rare earth element which forms a solid solution in the crystal structure of LaAl ₁₁ O ₁₈ and exhibits excellent etching resistance to fluorine-based plasma. Substituted in place of or complexed with the garnet crystal phase has excellent plasma resistance and phase stability.

According to the rare earth oxide-alumina ceramics having plasma characteristics according to the present invention, since secondary phases such as Al ₂ O ₃ do not exist or are very small, selective etching of Al ₂ O ₃ does not occur and contaminant It is less likely to occur.

In addition, according to the rare earth oxide-alumina-based ceramic having plasma characteristics according to the present invention, since it contains a garnet crystal phase, it has excellent thermal phase stability and can be used as a heat shielding material because of its excellent mechanical properties at high temperature. have.

According to the method of manufacturing a rare earth oxide-alumina ceramic having plasma characteristics according to the present invention, since the sintering process is performed at a high temperature of 1500 ° C. or higher, the surface layer is dense and induces the formation of YF ₃ , GdF ₃ or LaF ₃ by surface etching. To improve the corrosion resistance to the plasma.

1 is a composition triangle showing the composition change of A ₃ Al ₅ O ₁₂ (A is Gd or Y) according to the addition of Y in the Al ₂ O ₃ -GdAlO ₃ -YAlO ₃ system according to the present invention.
Figure 2 is a composition triangular diagram showing the composition change of BAl ₁₁ O ₁₈ (B is La or Y) with the addition of Y in the Al ₂ O ₃ -LaAlO ₃ -YAlO ₃ system according to the present invention.
3 is a graph showing a change in crystal phase generated by changing the content of Y by 20 mol% of the total rare earth elements in the composition (Gd · Y) ₃ Al ₅ O ₁₂ according to the present invention.
4 is a graph showing the relative mole fraction of garnet, GdAlO ₃ and Al ₂ O ₃ according to the amount of Gd added according to the present invention.
5 and 6 are field emission scanning electron microscope (FE-SEM) photographs showing microstructures measured by reflecting electron images for the case where the Y content is 60 and 0 mol%, respectively.
7 is a phase equilibrium diagram at 1680 ° C. according to the composition of Al ₂ O ₃ -GdAlO ₃ -YAlO ₃ system.
8 is a graph showing the rate at which (Gd · Y) ₃ Al ₅ O ₁₂ is etched under the conditions of the fluorine plasma according to the present invention.
9 is a graph showing a change in crystal phase generated by changing the content of Y by 20 mol% of the total rare earth elements in the (La · Y) Al ₁₁ O ₁₈ composition according to the present invention.
10 is a graph showing the relative mole fraction of (La · Y) Al ₁₁ O ₁₈ , garnet and Al ₂ O ₃ according to the amount of Y added according to the present invention.
11 and 12 are field emission scanning electron microscope (FE-SEM) photographs showing microstructures measured by reflecting electron images for the case where the Y content is 60 and 0 mol%, respectively.
FIG. 13 is a phase equilibrium diagram at 1680 ° C. according to the composition of an Al ₂ O ₃ —LaAlO ₃ —YAlO ₃ system.
14 is a graph showing the rate at which (La · Y) Al ₁₁ O ₁₈ is etched under the conditions of fluorine plasma according to the present invention.
15 is LaAl ₁₁ O ₁₈ according to the present invention This graph shows the binding energy of 2p electrons of Al atoms in the sintered body.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various modifications may be made without departing from the scope of the present invention. It is not.

The present invention is a rare earth oxide-alumina-based ceramic having a composition of A ₃ Al ₅ O ₁₂ , wherein the A site is composed of Gd _x Y _1-x (0 <x≤0.8), and Gd and Y are atomically substituted with each other. A rare earth oxide-alumina-based ceramic having plasma characteristics including a garnet crystal phase forming a solid solution having a structure present in the present invention is provided. In the rare earth oxide-alumina ceramic of (Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ composition, I ₍₂₁₁₎ which is the diffraction peak intensity of garnet structure, I ₍₁₁₀₎ which is the diffraction peak intensity of GdAlO ₃ structure, When the relative amounts of the garnet crystal phase, the GdAlO ₃ crystal phase and the corundum crystal phase were measured from the diffraction peak intensity I ₍₁₀₄₎ of the corundum structure, the amount of the corundum crystal phase was less than or equal to 10% of the total crystal phase. In addition, since secondary phases such as Al ₂ O ₃ having a corundum structure do not exist or are very small, selective etching of Al ₂ O ₃ does not occur and contaminants are less likely to be generated. In the rare earth oxide-alumina ceramic having the A ₃ Al ₅ O ₁₂ composition, the A site is made of Gd _x Y _1-x (0 < _x ≦ 0.5), so that the etching rate of the fluorine plasma is Y ₃ Al ₅ O ₁₂ . It may be smaller than ceramic.

In addition, the present invention is a rare earth oxide-alumina ceramic having a BAl ₁₁ O ₁₈ composition, wherein the B site is made of La _x Y _1-x (0 <x <1), and includes a LaAl ₁₁ O ₁₈ crystal phase and a garnet crystal phase. In addition, the present invention provides a rare earth oxide-alumina ceramic having an etching rate with respect to fluorine-based plasma having a smaller plasma resistance than that of a ceramic having a LaAl ₁₁ O ₁₈ composition. In the rare earth oxide-alumina-based ceramic having a (La _x Y _1-x ) Al ₁₁ O ₁₈ composition, I _{(104) in the} range of 0.8≤x <1 and the diffraction peak intensity of the corundum structure and the diffraction peak intensity of the garnet structure the amount of the I ₍₂₁₁₎ and, LaAl ₁₁ O nose from a diffraction peak intensity in I ₍₀₁₂₎ of ₁₈ reondeom crystal phase, garnet crystal phase and LaAl ₁₁ O ₁₈ as measured by the relative amount of the crystal phase co reondeom amount of the whole crystal of the crystal phase Less than or equal to 10%, and because secondary phases such as Al ₂ O ₃ having a corundum structure do not exist or are very small, selective etching of Al ₂ O ₃ does not occur, and contaminants are less likely to occur. Lose.

In the present invention, the rare earth oxide-alumina-based plasma resistance is examined to replace Y ₂ O _3, which is irregularly supplied worldwide, with other rare earth oxides, or to reduce the use amount.

For example, various phases exist as Al ₂ O ₃ is added to Y ₂ O ₃ . Y ₃ Al ₅ O ₁₂ (YAG) having a garnet structure is mentioned as a compound with alumina which contains the least Y ₂ O ₃ . If the content of alumina is increased than the correct Y ₃ Al ₅ O ₁₂ composition, Al ₂ O ₃ is present as a second phase, there is a concern that the selective etching of the alumina occurs in the plasma environment resulting in generation of contaminated particles. Therefore, in order to use the compound to which the rare earth oxide is applied as a plasma resistant material, it is necessary to select a region where the compound is stably present in a single phase.

Garnet crystal system A ₃ Al ₅ O ₁₂ is a material that can be used as a heat shielding material because of excellent thermal phase stability and excellent mechanical properties at high temperatures. In addition, the Garnet crystal system has a large cubic unit cell with a lattice constant of 1200 pm, and one cell contains about 160 atoms. Thus, various materials can be doped and the properties can be easily adjusted to the composition.

In particular, if the surface of the oxide specimen is completely fluorinated under conditions for application to plasma etching and has an ideal composition of YF ₃ , LaF _3, and GdF ₃ , the rate at which the surface layer is etched is due to sputtering of the surface layer by incident ions. Can be influenced by the speed being. The sputtering rate will depend on the latent heat of sublimation of the material being sputtered.

Accordingly, when plasma etching is performed on an oxide having a garnet crystal structure, a collision between fluorine ions and the surface layer occurs and a fluorine compound is formed on the surface layer. In the case of the elements constituting the garnet crystal (A ₃ Al ₅ O ₁₂ ), Y, Gd or La is located at the A site, and since the valence at the A site constitutes a fluorine compound, To be excellent.

The present invention proposes a material having excellent plasma resistance while forming a garnet crystal structure based on Y ₂ O ₃ having an etching property superior to Al ₂ O ₃ in a fluorine-based plasma.

In addition, in LaAl ₁₁ O ₁₈ prepared by mixing Al ₂ O ₃ and La ₂ O ₃ , the formation of LaAl ₁₁ O ₁₈ increases the fracture toughness due to a crack bridging phenomenon. As a method of increasing fracture toughness, a method of substituting La with Y is used, and a material having excellent phase stability and excellent plasma resistance is proposed.

1 is a composition triangle showing the composition change of A ₃ Al ₅ O ₁₂ (A is Gd or Y) according to the addition of Y in the Al ₂ O ₃ -GdAlO ₃ -YAlO ₃ system according to the present invention.

Referring to FIG. 1, when mol% of the atoms constituting A in the garnet is 100%, A1 is 100 mol% of Gd, A2 is 80 mol% of Gd, A3 is 60 mol% of Gd, and A4 is 40 mol% of Gd. , A5 represents 20 mol% of Gd, and A6 represents 0 mol% of Gd. In Figure 1, Gd100 means that mol% of Gd is 100mol% and Gd0 means that mol% of Gd is 0mol%.

The composition of A2 to A6 in FIG. 1 is composed only of the garnet phase even after sintering, thus showing excellent plasma resistance when performing a test for plasma etching.

In the case of the rare earth oxide-alumina ceramic having excellent plasma characteristics according to the present invention, the transition of the crystal phase was observed while changing the composition from A1 to A6, and the etching resistance against fluorine plasma was measured.

In the rare earth oxide-alumina ceramic having plasma characteristics according to the present invention, in the A ₃ Al ₅ O ₁₂ composition of the garnet crystal system, the A site is composed of Gd _x Y _{1 -x} (0 <x≤0.8). desirable.

Figure 2 is a composition triangular diagram showing the composition change of BAl ₁₁ O ₁₈ (B is La or Y) with the addition of Y in the Al ₂ O ₃ -LaAlO ₃ -YAlO ₃ system according to the present invention.

Referring to FIG. 2, when the mol% of atoms constituting B in the composition of B1 to B6 is 100%, B1 is 100 mol% of La, B2 is 80mol% of La, B3 is 60mol% of La, B4 Is 40 mol% La, B5 is 20 mol% La and B6 is 0 mol% La. In Figure 2 La100 means that mol% of La is 100mol%, La0 means that mol% of La is 0mol%.

In FIG. 2, only B1 may exhibit a single phase BAl ₁₁ O ₁₈ (B is La or Y) even after sintering, and may show secondary phases such as Al ₂ O ₃ or Y ₃ Al ₅ O ₁₂ depending on the addition of Y. will be.

In the case of the rare earth oxide-alumina ceramic having plasma characteristics according to the present invention, the B site is preferably composed of La _x Y _1-x (0 <x <1) in the BAl ₁₁ O ₁₈ composition.

Hereinafter, a method of manufacturing a rare earth oxide-alumina ceramic having plasma characteristics according to the present invention will be described.

The oxide powder containing the element to be added to the A site in the composition of A ₃ Al ₅ O ₁₂ is weighed, or the oxide powder containing the element to be added to the B site to have the composition of BAl ₁₁ O ₁₈ , respectively.

In the composition of A ₃ Al ₅ O ₁₂ , Gd and Y, which are rare earth elements, may be added together to the A site, and Gd ₂ O ₃ , Y ₂ O ₃ , and the like may be used as oxides as source materials of these elements. (Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ (0 <x≤0.8) Calculate the molar ratio of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O _{3 to form} a composition Al ₂ O ₃ powder, Y ₂ O ₃ powder and Gd ₂ O ₃ powder are weighed. At this time, in order to make the rare earth oxide-alumina ceramic of the A ₃ Al ₅ O ₁₂ composition smaller than that of the Y ₃ Al ₅ O ₁₂ composition in the etching rate with respect to the fluorine-based plasma, the A site is Gd _x Y _1-x Al ₂ O ₃ powder, Y ₂ O ₃ powder and Gd ₂ O ₃ powder can be weighed by calculating the molar ratios of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ to (0 <x≤0.5). have.

In addition, in the BAl ₁₁ O ₁₈ composition, the rare earth elements La and Y may be added together at the B site, the source material of La may be La ₂ O _3, and the source material of Y may be Y ₂ O ₃ . _{(La x Y 1-x)} Al 11 O 18 (0 <x <1) the composition fulfill _{Al 2 O 3, Y 2 O} 3 and La ₂ by calculating the molar ratio of O ₃ Al ₂ O _3, powder, Y ₂ O ₃ powder and La ₂ O ₃ powder are weighed. At this time, the B site is La _x Y _1-x (0.8 ≦ _x <1) so that the alumina (Al ₂ O ₃ ) crystal phase does not exist or is very small in the rare earth oxide-alumina-based ceramic having the BAl ₁₁ O ₁₈ composition. be made of Al ₂ O _3, Y ₂ O ₃ and it is possible to calculate the molar ratio of La ₂ O ₃ were weighed to the Al ₂ O ₃ powder, Y ₂ O ₃ powder, and La ₂ O ₃ powder.

An oxide powder, which is a source raw material containing an element to be added to the A site or an element to be added to a B site, and an Al ₂ O ₃ powder, which is a source raw material of Al, are mixed. The mixing may use a ball milling process.

Hereinafter, the ball milling process will be described in detail.

The ball mill is rotated at a constant speed to mechanically grind and uniformly mix the source raw materials. The balls used for ball milling may use balls made of ceramics such as zirconia, and the balls may be all the same size or may be used with balls having two or more sizes. The size of the balls, the milling time, and the rotation speed per minute of the ball miller are adjusted so as to be crushed to the target particle size. For example, in consideration of the particle size, the size of the ball can be set in the range of about 1 mm to 10 mm, and the rotational speed of the ball mill can be set in the range of about 50 to 500 rpm. Ball milling is performed for 1 to 100 hours in consideration of the target particle size and the like. By ball milling, the source raw materials are ground to finely sized particles, have a uniform particle size distribution, and are mixed uniformly.

A drying process is performed while stirring using a magnetic bar so that the mixed slurry is not precipitated. The drying process may be a constant drying for 2-100 hours in an oven 60 ~ 100 ℃.

The mixed source raw materials are charged into a mold and molded. The molding is charged into a metal mold having a diameter of 10 to 20 mm, first uniaxially formed at a pressure of 20 to 100 MPa for a predetermined time (for example, 1 to 10 minutes), and then again to a predetermined time (for example, 1 to 1 to 120 MPa). 10 minutes) by cold isostatic pressing. Through this process it is possible to prepare a molded body of A ₃ Al ₅ O ₁₂ or BAl ₁₁ O _{18 It} is possible to implement a rare earth oxide-alumina ceramic that does not generate thermal stress. Also close packing is achieved between the particles.

The molded specimen is sintered to form a rare earth oxide-alumina ceramic material. It is preferable to perform the said sintering for about 1 to 48 hours at the temperature of about 1500-1800 degreeC. The sintering step can be carried out by increasing the temperature to a sintering temperature at a temperature increase rate of 2 to 10 ° C./min, maintaining the constant time (for example, about 1 to 48 hours), and sintering to normal temperature. At this time, the sintering atmosphere is preferably sintered in an oxidizing atmosphere.

Hereinafter, experimental examples of the method of preparing a rare earth oxide-alumina ceramic having plasma characteristics according to the present invention will be described in more detail, and the present invention is not limited to the following experimental examples.

In the experiments below, Y ₃ Al ₅ O ₁₂ and LaAl ₁₁ O ₁₈ instead of Y are used instead of Y ₃ Al ₅ O ₁₂ and LaAl ₁₁ O ₁₈ to make stable compounds with the least rare earth oxides in the Gd-Y-Al and La-Y-Al system. The upper stable region was examined while substituting Gd and Y instead of La. After exposing the prepared specimen to fluorine-based plasma, the etch rate was measured and the composition of the surface was analyzed using X-ray photoelectron spectroscopy (XPS).

XPS (PHI 5000, Ulvac-phi Co., Japan) was used to analyze the chemical composition and chemical bonding state of the specimen exposed to the plasma. On the other hand, in order to analyze the crystal phase of the sintered compact by using a high-power X-ray diffractometer (D / max-2500, Rigaku, Japan) to scan the powder of the sintered compact pulverized at a speed of 10 ^o / min at 15 kV, 30 mA A pattern was obtained. In order to observe the surface microstructure and components, the specimens were coated with platinum and analyzed using FE-SEM (JSM-6701F, Jeol, Japan). In addition, the etching depth of the test piece was measured using a surface profiler (surfcorder ET3000, Kosaka Lab., Japan).

<Experimental Example 1>

Al ₂ O ₃ (AKP-30, Sumitomo Chemical Co., Japan), Y ₂ O ₃ (C-grade, HC Stark, Germany) and Gd ₂ O ₃ (99.9%, Kojundo Chemical Co, Japan) as source raw materials Used.

As shown in FIG. 1, the composition used in the experiment was 100% by mol% of atoms constituting A when the crystal phase of A ₃ Al ₅ O ₁₂ , which is a garnet in an Al ₂ O ₃ -GdAlO ₃ -YAlO ₃ system, was used. When A1 is 100 mol% Gd, A2 is 80 mol% Gd, A3 is 60 mol% Gd, A4 is 40 mol% Gd, A5 is 20 mol% Gd and A6 is 0 mol% Gd.

As a prepared source material, a dispersant (RE 610, Rhodia Co., USA) was added using ethanol as a solvent. The mixed solution of ethanol to which the dispersant was added was milled for 20 hours using Al ₂ O ₃ balls. The mixed slurry was first dried while stirring on a hot plate, and then further dried in an oven at 80 ° C. for 12 hours to prepare a powder raw material ground using a mortar.

The prepared powder was filled into a metal mold having a diameter of 10 mm, and first molded at low pressure, and then a molded product having a thickness of 2 mm was obtained at a pressure of 200 MPa using a cold isostatic press (CIP).

The molded test piece was heated to 1680 ° C. at 5 ° C./min in an air atmosphere, sintered for 4 hours, and cooled to prepare a sintered body.

The sintered test pieces were mirror polished using a 9,3,1 (μm) diamond paste, and washed with ultrasonic waves in acetone.

The intermediate region of the polished test piece surface was masked using a Jabton tape so that only 0.3 mm in width was exposed. An etching apparatus of ICP type (Versaline, UNAXIS Co, USA) was used as an etching apparatus to evaluate the plasma resistance.

CF ₄ and O ₂ were used as the etching gas, and the exposure time to the plasma was 60 minutes with six exposures of 10 minutes each. Table 1 is a table showing the etching conditions of the rare earth oxide-alumina ceramic having a plasma resistance according to the present invention.

parameter Condition RF power 700 W RF power (bias) 200W CF ₄ 30SCCM O ₂ 5SCCM Ar 10SCCM pressure 10 mTorr

3 is a graph showing a change in crystal phase generated by changing the content of Y by 20 mol% of the total rare earth elements in the composition (Gd · Y) ₃ Al ₅ O ₁₂ according to the present invention.

Referring to FIG. 3, except for Gd100, the garnet crystal structure is shown.

In view of the change of the crystal phase caused by changing the Y content by 20 mol%, only a phase having a gannet crystal structure exists in the range of 0 to 80 mol% of the relative content of Gd among the rare earth elements, and the content of Gd At 100 mol%, the garnet phase becomes unstable and GdAlO ₃ Phase separation takes place with and Al ₂ O ₃ . Therefore, as a rare earth oxide-alumina ceramic having plasma properties according to the present invention, when the A site is Gd _x Y _1-x (0 <x≤0.8) in the composition of A ₃ Al ₅ O ₁₂ , the monolithic phase of the garnet It can be said that it consists only of).

4 is a graph showing the relative mole fraction of garnet, GdAlO ₃ and Al ₂ O ₃ according to the amount of Gd added according to the present invention.

Referring to Fig. 4, the diffraction intensity ratio between peaks with little overlap in X-ray diffraction appears, and the change is indicated. Estimate the relative amounts of each phase from the diffraction peak intensities of the garnet structure I ₍₂₁₁₎ , I ₍₁₁₀₎ of the GdAlO ₃ structure, and I ₍₁₀₄₎ of the corundum structure in (Gd · Y) ₃ Al ₅ O ₁₂ It was. From Figure 4 it can be determined (Gd · Y) is very wider range of ₃ Al ₅ O ₁₂ solid solution having a garnet structure. In FIG. 4, the right direction is a direction in which mol% of Gd is increased, and the left direction is a direction in which mol% of Y is increased.

This difference in solid solution appears to be due to the change in ion size.

If you consider the size of the ion Gd ^{+ 3} and Y ^{3 +,} Gd ^{3 +} is Gd ^{+ 3} as 0.94Å, Y ^{3 +} a 0.9Å has a large ionic size, about 4.4% more than Y ^3+. Thus, Gd ^{+ 3} is the employment wide range can be easily substituted by Y ^{3 +.}

5 and 6 are field emission scanning electron microscope (FE-SEM) photographs showing microstructures measured by reflecting electron images for the case where the Y content is 60 and 0 mol%, respectively.

Referring to Figure 5, it can be seen that when the content of Gd is 40mol% (Gd40) is composed of a single phase. The EDX analysis also showed that the atomic ratio of Y: Gd was 65:35, similar to the value expected from the starting composition.

Referring to FIG. 6, in the case of (Gd · Y) ₃ Al ₅ O ₁₂ , when Gd is 100 mol% (Gd100), light-colored GdAlO ₃ and dark-colored Al ₂ O ₃ as predicted by X-ray diffraction analysis You can check.

Therefore, when combined with the results of X-ray diffraction analysis, the solid solution range of (Gd · Y) ₃ Al ₅ O ₁₂ may be 80 mol% or more, based on the Gd content in the rare earth elements.

7 is a phase equilibrium diagram at 1680 ° C. according to the composition of Al ₂ O ₃ -GdAlO ₃ -YAlO ₃ system.

Referring to FIG. 7, A ₃ Al ₅ O ₁₂ (A is Gd or Y) from C to D forms a solid solution, and particles entering the A site include Gd or Y. The point C is a point at which Gd becomes 80 mol%. In contrast, the point D is a point at which Gd becomes 0 mol%.

It was confirmed in the X-ray diffraction analysis of Figure 3 that the C to D is composed of a single phase of the garnet irrespective of the change in composition.

8 is a graph showing the rate of etching under the conditions of fluorine plasma according to the present invention. In Figure 8, the horizontal axis represents the content of Gd. To the right, the content of Gd increases. The etch rates for quartz glass, sapphire and Y ₂ O ₃ were reported together under the same conditions for comparison with the results according to the invention.

Referring to FIG. 8, it can be seen that the etch rate of Y ₂ O ₃ is the slowest.

It can be seen that the etching rate by plasma etching is more dependent on the proportion of rare earth metals than the substitution of Gd or Y. For example, in the (Gd _x Y _{1 -x} ) ₃ Al ₅ O ₁₂ (0 <x≤0.8) sinter, which represents a solid solution, the maximum deviation of the etching rate is ± 15 as the Gd content of the rare earth content changes from 0 to 80 mol%. It was only%. In the rare earth oxide-alumina ceramic having A ₃ Al ₅ O ₁₂ composition, when the A site is Gd _x Y _1-x (0 < _x ≦ 0.5), the etching rate with respect to the fluorine plasma is Y ₃ Al ₅ O ₁₂ Small compared to

The reason why the etching rate by plasma etching varies depending on the rare earth metal is considered to be related to the generation of fluorine compounds.

In the experimental conditions according to the given Table 1, the etching rate of each material to the etching rate of quartz glass is about 18.6% for sapphire single crystal, 1.5% for Y ₂ O ₃ , and (Gd _x Y _{1 -x} ) ₃ Al ₅ O ₁₂ (0 <x <1) showed an etching rate of 2.8 ~ 3.8%.

<Experimental Example 2>

Al ₂ O ₃ (AKP-30, Sumitomo Chemical Co., Japan), Y ₂ O ₃ (C-grade, HC Stark, Germany) and La ₂ O ₃ (99.9%, Kojundo Chemical Co, Japan) as source raw materials Used.

The composition used in the experiment is 100% mol% of the atoms constituting B in the composition of BAl ₁₁ O ₁₈ (B is La or Y) in the Al ₂ O ₃ -LaAlO ₃ -YAlO ₃ system, as shown in FIG. In this case, B1 is 100 mol% of La, B2 is 80mol% of La, B3 is 60mol% of La, B4 is 40mol% of La, B5 is 20mol% of La and B6 is 0mol% of La. .

As a prepared source material, a dispersant (RE 610, Rhodia Co., USA) was added using ethanol as a solvent. The mixed solution of ethanol to which the dispersant was added was milled for 20 hours using Al ₂ O ₃ balls. The mixed slurry was first dried while stirring on a hot plate, and then further dried in an oven at 80 ° C. for 12 hours to prepare a powder raw material ground using a mortar.

The prepared powder was filled into a metal mold having a diameter of 10 mm, and first molded at low pressure, and then a molded product having a thickness of 2 mm was obtained at a pressure of 200 MPa using a cold isostatic press (CIP). The molded test piece was heated to 1680 ° C. at 5 ° C./min in an air atmosphere, sintered for 4 hours, and cooled to prepare a sintered body.

The sintered test pieces were mirror polished using a 9,3,1 (μm) diamond paste, and washed with ultrasonic waves in acetone.

The intermediate region of the polished test piece surface was masked using a Jabton tape so that only 0.3 mm in width was exposed.

CF ₄ and O ₂ were used as the etching gas, and the exposure time to the plasma was 60 minutes with six exposures of 10 minutes each. Experimental conditions were carried out under the conditions of Table 1 in the same manner as in Example 1.

9 is a graph showing a change in crystal phase generated by changing the content of Y by 20 mol% of the total rare earth elements in the (La · Y) Al ₁₁ O ₁₈ composition according to the present invention.

Referring to FIG. 9, except for La 100, all of Y ₂ O ₃ and garnet (Y ₃ Al ₅ O ₁₂ ) are observed. In the composition of (La · Y) Al ₁₁ O ₁₈ , when the relative content of La in rare earth elements is 80 mol%, the crystal phases of garnet and corundum structures already appear, and as La decreases, When Al ₁₁ O ₁₈ phase is reduced and La content reaches 0 mol%, it consists of Y ₃ Al ₅ O ₁₂ of garnet structure and Al ₂ O ₃ crystal phase of corundum structure.

10 is a graph showing the relative mole fraction of (La · Y) Al ₁₁ O ₁₈ , garnet and Al ₂ O ₃ according to the amount of Y added according to the present invention.

Referring to Fig. 10, the diffraction intensity ratio between peaks with little overlap in X-ray diffraction appears, and the change is indicated. _{(La · Y) Al 11 O} 18 each on the relative amounts from the diffraction peak intensity in _{I (104), I (211} ), I (012) of LaA _l1 O ₁₈ garnet structure of the corundum structure were estimated from. 10, it was confirmed that the range of the solid solution of (La · Y) Al ₁₁ O ₁₈ was very narrow and three phases coexist in a wide range of composition. In FIG. 10, the right direction is a direction in which mol% of La increases, and the left direction is a direction in which mol% of Y increases.

These differences in employment ranges can be considered in conjunction with the change of the ion size of La ^{3 +,} Y ^{3 +.} And Y ^{+ 3} are 0.9Å, La ^{3 +} is 1.03Å. Therefore, La ^{3 +} has a larger ionic size of about 14.4%. Therefore, La ^{3 +} cannot be easily substituted with Y ^{3 +} ions, so it can be estimated that the range of solid solution is narrow.

11 and 12 are field emission scanning electron microscope (FE-SEM) photographs showing microstructures measured by reflecting electron images for the case where the Y content is 60 and 0 mol%, respectively.

Referring to FIG. 11, when the La content is 40 mol% (La40), the reflection electron image shows that three phases, E1, E2, and E3, exist. EDX analysis confirmed that E1 is a garnet crystal of Y ₃ Al ₅ O ₁₂ , E2 is a LaAl ₁₁ O ₁₈ crystal and E3 is Al ₂ O ₃ .

Referring to Figure 12, when the La content is 100mol% (La100) is composed of a single phase of LaAl ₁₁ O ₁₈ .

These results are in agreement with the results expected from the difference in ion size between the rare earth elements.

FIG. 13 is a phase equilibrium diagram at 1680 ° C. according to the composition of an Al ₂ O ₃ —LaAlO ₃ —YAlO ₃ system.

Referring to FIG. 13, the range in which BAl ₁₁ O ₁₈ (B is La or Y) forms a solid solution is narrow.

14 is a graph showing the rate of etch in the conditions of fluorine plasma according to the present invention. In Figure 14, the horizontal axis represents the content of La. To the right, the La content increases. The etch rates for quartz glass, sapphire and Y ₂ O ₃ were reported together under the same conditions for comparison with the results according to the invention.

Referring to Figure 14, it can be confirmed that the fluorine plasma etch rate of BAl ₁₁ O ₁₈ (B is La or Y) is 20 ~ 40nm / min. In the experimental conditions according to the given Table 1, the etching rate of each material to the etching rate of quartz glass is about 18.6% for sapphire single crystal, 1.5% for Y ₂ O ₃ , and 8.6 ~ 11.1 for (LaY) Al ₁₁ O ₁₈ sintered body. The etching rate was%. Rare earth oxides BAl ₁₁ O ₁₈ composition - that when the B-site in an alumina-based ceramic consisting of _{La x Y 1-x (0} <x <1) the etch rate for a fluorine-based plasma small compared to the ceramic of LaAl ₁₁ O ₁₈ composition You can check it.

15 is LaAl ₁₁ O ₁₈ according to the present invention This graph shows the binding energy of 2p electrons of Al atoms in the sintered body.

Referring to FIG. 15, LaAl ₁₁ O ₁₈ Sintered body can be seen that the binding energy of Al 2p is slightly moved upward.

X-ray photoelectron spectroscopy (XPS) was used to analyze the composition and chemical bonding of the surface exposed to the plasma. XPS is a tool used to scan the X-rays on the surface of the sample to find the binding energy of the electrons protruding from the kinetic energy of the electrons coming out of the sample.

Table 2 shows LaAl ₁₁ O ₁₈ The surface component analysis result of the sintered compact was shown, and the atomic sensitivity factor used for composition calculation was shown together. However, BAl ₁₁ O ₁₈ Since back to fluorine plasma environment consisting of the etch rate measurement on the sintered body, the surface layer is determined that there is a LaF ₃ or AlF ₃ is formed. Therefore, the binding energy of electrons in the 2p period in Al seems to be due to the combined bonding of F and Al.

Referring to Table 2, it was confirmed that the surface of the fluorine content is very high, and to confirm the binding of the cation and the fluorine ion, the Al peak calibrated based on the XPS peak position 285 eV of the surface carbon was observed.

element Selected peak Atomic fraction,% Atomic sensitivity factor
(Atomic sensitivity factor for composition calculation) Al 2p 16.3 0.249 La 4d 6.8 2.730 F 1 s 43.8 One O 1 s 28.3 0.733 C 1 s 4.8 0.314

It was observed that the binding energy shifted up to about 1.8 eV when exposed to plasma compared to the position 73.8 eV of Al _2p observed in the conventional oxide.

From these results, the binding energy of Al 2p in AlF ₃ , a fluorine compound generated by the collision of BAl ₁₁ O ₁₈ (B is La) and F ions, is 74 ~ 77 eV.

The increase in the binding energy of Al _2p can be thought to be due to the higher electron-extraction energy barrier at core level 2p, as the electronegative fluorine binds to aluminum on the surface of the test specimen, making the aluminum ions more positive. Can be. Therefore, it can be said that the increase of the fluorine content on the surface and the change of the peak position show the same tendency.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, This is possible.

Claims (10)

A rare earth oxide-alumina ceramic having A ₃ Al ₅ O ₁₂ composition, wherein the A site is composed of Gd _x Y _1-x (0 <x≤0.8), and has a structure in which Gd and Y are atomically substituted with each other. In the rare earth oxide-alumina ceramic of (Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ composition containing a solid solution garnet crystal phase, I ₍₂₁₁₎ which is the diffraction peak intensity of the garnet structure and the diffraction peak of the GdAlO ₃ structure When the relative amounts of the garnet crystal phase, the GdAlO ₃ crystal phase, and the corundum crystal phase were measured from the intensity I ₍₁₁₀₎ and the diffraction peak intensity of the corundum structure ₍ I ₁₀₄₎ , the amount of the corundum crystal phase was the total crystal phase. Rare earth oxide-alumina ceramics having plasma properties, characterized in that less than or equal to 10% by weight.
Rare earth oxide-alumina ceramic with BAl ₁₁ O ₁₈ composition, B site consisting of La _x Y _1-x (0 <x <1), containing LaAl ₁₁ O ₁₈ crystal phase and garnet crystal phase, Rare earth oxide-alumina-based ceramics having plasma properties, characterized in that the etching rate is smaller than that of the LaAl ₁₁ O ₁₈ composition.
The rare earth oxide-alumina ceramic according to claim 1 or 2, wherein the rare earth oxide-alumina ceramic has an etching rate lower than that of quartz and sapphire under fluorine plasma etching conditions. .
According to claim 1, The rare earth oxide-alumina-based ceramic of the A ₃ Al ₅ O ₁₂ composition of the A site is Gd _x Y _1-x (0 < _x ≤ 0.5) the etching rate for the fluorine-based plasma Y ₃ A rare earth oxide-alumina-based ceramic having plasma characteristics, which is smaller than that of an Al ₅ O ₁₂ composition.
3. The method of claim _{2, (La x Y 1-x} ) Al 11 O 18 composition of the rare earth oxide - and 0.8≤x <1 in the range of alumina-based ceramic, the nose and the diffraction peak intensity I ₍₁₀₄₎ of reondeom structure, garnet amount of the diffraction peak intensity in I ₍₂₁₁₎ of the structure, as from a diffraction peak intensity in I ₍₀₁₂₎ of LaAl ₁₁ O ₁₈ as measured by the relative amount of the corundum crystalline phase, garnet crystal phase and LaAl ₁₁ O ₁₈ crystal corundum crystals A rare earth oxide-alumina ceramic having plasma characteristics, characterized in that less than or equal to 10% of the total crystal phase.
In the method for producing a rare earth oxide-alumina ceramic of A ₃ Al ₅ O ₁₂ composition,
(Gd _x Y _1-x ) ₃ Al ₅ O ₁₂ (0 <x≤0.8) Calculate the molar ratio of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O _{3 to form} a composition Al ₂ O ₃ powder, Y ₂ O Weighing and mixing ₃ powder and Gd ₂ O ₃ powder;
Molding the mixture of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ to form a closest fill; And
Method for producing a rare earth oxide-alumina ceramic having a plasma resistance characteristics comprising the step of sintering the molded product at a temperature of 1500 ~ 1800 ℃.
In the method for producing a rare earth oxide-alumina ceramic having a BAl ₁₁ O ₁₈ composition,
_{(La x Y 1-x)} Al 11 O 18 (0 <x <1) the composition fulfill _{Al 2 O 3, Y 2 O} 3 and La ₂ by calculating the molar ratio of O ₃ Al ₂ O _3, powder, Y ₂ O Weighing and mixing ₃ powder and La ₂ O ₃ powder;
Shaping the mixture of Al ₂ O ₃ , Y ₂ O ₃ and La ₂ O ₃ to form a closest fill; And
Method for producing a rare earth oxide-alumina ceramic having a plasma resistance characteristics comprising the step of sintering the molded product at a temperature of 1500 ~ 1800 ℃.
The method of claim 6 or 7, wherein the mixing uses a ball milling process, phosphoric acid is used to disperse the oxides in the ball milling process, and the molding is performed using a cold hydrostatic molding machine. Method for producing a rare earth oxide-alumina-based ceramic having.
The method according to claim 6, wherein the A site is Gd _{x in} order to make the rare earth oxide-alumina ceramic of the A ₃ Al ₅ O ₁₂ composition smaller than that of the Y ₃ Al ₅ O ₁₂ composition in the etching rate with respect to the fluorine-based plasma. Al ₂ O ₃ powder, Y ₂ O ₃ powder and Gd ₂ O ₃ powder by calculating the molar ratio of Al ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ to be made of Y _1-x (0 <x≤0.5) A method for producing a rare earth oxide-alumina ceramic having plasma characteristics, characterized in that weighing and mixing.
According to claim 7, Al ₂ O ₃ , Y ₂ O ₃ and La so that the B site in the rare earth oxide-alumina-based ceramic composition of BAl ₁₁ O ₁₈ is La _x Y _1-x (0.8≤x <1) ₂ O ₃ by calculating the molar ratio of Al ₂ O ₃ powder, Y ₂ O ₃ powder and a rare earth oxide with the plasma characteristics, characterized in that the weighing and mixing the La ₂ O ₃ powder manufacturing method of alumina-based ceramic.

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