JP7500007B2 - Holding member and manufacturing method thereof - Google Patents

Description

The present invention relates to a plate-shaped holding member that is integrally formed and holds the object to be treated on its surface, and a method for manufacturing the same.

An AlN electrostatic chuck is a part of a semiconductor manufacturing device, and adheres a substrate to its surface. A molded body hot pressing method is known as one of the methods for manufacturing such an AlN electrostatic chuck. In this method, an additive and a binder are mixed with an AlN raw material and the mixture is _granulated . At this time, a few wt% of _Y2O3 is added to the AlN raw material in order to increase the thermal conductivity of the sintered body.

The granulated granules are molded to produce multiple molded bodies, and the molded bodies are degreased to produce degreased bodies. The degreased bodies are then stacked with electrodes sandwiched between them, and the stack is hot-pressed and sintered to produce an AlN electrostatic chuck (see, for example, Patent Document 1).

At least an electrode for electrostatic attraction is embedded inside the AlN electrostatic chuck obtained in this way. A surface layer is formed as an insulating layer between the electrode for electrostatic attraction and the substrate mounting surface. By designing the volume resistivity of this surface layer to be within a certain range in the temperature range in which it is used, a strong electrostatic attraction force can be generated between the chuck and the substrate.

Patent No. 6148845

However, electrostatic chucks manufactured using conventional compact pressing methods do not have a sufficiently reduced volume resistivity in the insulating layer region. As a result, the electrostatic adsorption force is insufficient, especially in the temperature range (200 to 400°C).

The present invention was made in consideration of these circumstances, and aims to provide a holding member having a reduced volume resistivity in the surface layer and capable of exerting a strong electrostatic adsorption force on the object to be treated, and a method for manufacturing the same.

(1) In order to achieve the above object, the holding member of the present invention is a plate-shaped holding member that is integrally formed and holds a processing object on its surface, and includes a surface layer and a bulk layer formed of a ceramic sintered body mainly composed of AlN, and an electrode provided between the surface layer and the bulk layer, and is characterized in that the surface layer contains YAG particles in the AlN grain boundaries of the ceramic sintered body, but does not contain YAP particles or YAM particles. This reduces the volume resistivity of the surface layer compared to when YAP particles or YAM particles are included, and allows the surface layer to exert a strong electrostatic adsorption force on the processing object.

(2) The retaining member of the present invention is also characterized in that the ratio of the particle diameter of the YAG particles to the particle diameter of the AlN particles is 0.3 or less. Since a large number of finely dispersed YAG particles are used in this way, the volume resistivity of the surface layer can be reduced.

(3) The retaining member of the present invention is also characterized in that the bulk layer contains YAP particles or YAM particles, but does not contain YAG particles, in the AlN grain boundaries of the ceramic sintered body. By containing YAP particles or YAM particles in the bulk layer in this way, the volume resistivity can be maintained relatively high, which suppresses leakage current and makes it easier to control the voltage of the electrodes.

(4) Furthermore, the retaining member of the present invention is characterized in that the bulk layer contains YAG particles in the AlN grain boundaries of the ceramic sintered body, but does not contain YAP particles or YAM particles. By making the surface layer and the bulk layer in this way the same structure, the manufacturing process can be simplified.

(5) The manufacturing method of the holding member of the present invention is a manufacturing method of a plate-shaped holding member that is integrally formed and holds a processing object on its surface, and includes the steps of granulating a raw material powder obtained by adding Y ₂ O ₃ to an AlN raw material to produce a plurality of compacts, degreasing the plurality of compacts to produce a plurality of degreased bodies, and stacking the plurality of degreased bodies with electrodes sandwiched therebetween and hot-press firing the stacked bodies, and is characterized in that in the degreasing step, a first degreased body that is disposed on the surface side during firing is produced under conditions where the degreasing temperature T1 (°C) and the degreasing time H1 (h) satisfy H1≧300/(T1-540). As a result, the surface layer obtained from the first degreased body contains YAG particles, but does not contain YAP particles or YAM particles. As a result, the volume resistivity of the surface layer is reduced, and a strong electrostatic adsorption force can be exerted on the processing object.

(6) The manufacturing method of the holding member of the present invention is characterized in that, in the degreasing process, a second degreased body is produced that is placed on the bulk side, which is opposite the surface side of the first degreased body, during firing under conditions where the degreasing temperature T2 (°C) and the degreasing time H2 (h) satisfy H2 < 300/(T2 - 540). As a result, the bulk layer obtained from the second degreased body contains YAP particles or YAM particles, which makes it possible to maintain a relatively high volume resistivity, suppress leakage current, and facilitate voltage control of the electrodes. In addition, carbonization of the electrodes can be suppressed, and the electrostatic adsorption function, RF characteristics, and heater function of the holding member can be stabilized.

(7) The method for producing a retaining member of the present invention is characterized in that the amount _{of Y2O3} added to the second degreased body arranged on the bulk side during firing is greater than the amount of _Y2O3 added to the first degreased body arranged on the surface side during firing, thereby making it possible to maintain the volume resistivity of the bulk layer obtained from the second degreased body higher than the volume resistivity of the surface _layer .

According to the present invention, the volume resistivity of the surface layer is reduced, and a strong electrostatic adsorption force can be exerted on the object to be treated.

FIG. 2 is a front cross-sectional view showing the holding member of the first embodiment. 3A to 3D are cross-sectional views each showing a schematic diagram of a manufacturing process of the first embodiment. 1 is a table showing the degreasing conditions and evaluation results of each sample. 1A and 1B are graphs in which the volume resistivity and particle size ratio data of each sample are plotted against the debinding temperature and the debinding time, respectively. 1 is a graph showing the volume resistivity of a surface layer at different measurement temperatures. 1 is a phase diagram of a Y ₂ O ₃ -Al ₂ O ₃ based compound. 13 is a SEM photograph showing a fracture surface of each sample obtained by changing the degreasing conditions. 1 is a table showing the degreasing conditions and evaluation results of each sample.

Next, an embodiment of the present invention will be described with reference to the drawings.

[First embodiment]
[Configuration of holding member]
FIG. 1 is a front cross-sectional view showing a holding member 100. The holding member 100 is formed in a plate shape such as a disk, and includes a surface layer 110, a bulk layer 120, and electrodes 150 and 160. The surface layer 110 and the bulk layer 120 are formed of a ceramic sintered body mainly composed of AlN, and contain a crystal phase of a complex oxide of Y ₂ O ₃ and Al ₂ O _3. In the example shown in FIG. 1, the electrode 150 is provided between the surface layer 110 and the bulk layer 120, and further, the electrode 160 for a heater is provided inside the bulk layer 120. The electrodes 150 and 160 are made of molybdenum or tungsten.

The holding member 100 is, for example, an electrostatic chuck, which is integrally formed from a ceramic material and holds the processing object on its surface by electrostatic adsorption force due to the Johnsen-Rahbek effect. In this case, the electrode 150 is used for electrostatic adsorption. If the material of the surface layer 110 of the electrode 150 has a volume resistivity within a predetermined range, the Johnsen-Rahbek effect is utilized. For the sake of adsorption force and ease of manufacture, it is preferable that the surface layer 110 is formed in the region from the surface (the surface on which the processing object is placed) to the electrode 150, but it may be formed in the region from the surface to just before the electrode 150, or may be formed from the surface to a position between the electrodes 150 and 160.

The AlN grain boundaries of the ceramic sintered body that constitutes the surface layer 110 contain YAG particles, but do not contain YAP or YAM particles. This reduces the volume resistivity of the surface layer 110 compared to when YAP or YAM particles are contained as particles, and allows the surface layer 110 to exert a strong electrostatic adsorption force on the object to be treated.

The composition can be evaluated by whether or not the peaks of YAG, YAM, and YAP are observed in X-ray diffraction. The presence or absence of a peak can be determined by whether or not there is a tip that shows an intensity twice or more higher than the background. The presence or absence of YAG particles can be determined by the presence or absence of a peak that appears at a diffraction angle of about 18.11° among the YAG diffraction peaks shown in the JCPDS card ICDD #01-073-3184. The presence or absence of YAM particles can be determined by the presence or absence of a peak that appears at a diffraction angle of about 30.60° among the YAM diffraction peaks shown in the JCPDS card ICDD #00-033-0368. The presence or absence of YAP particles can be determined by the presence or absence of a peak that appears at a diffraction angle of about 34.24° among the YAP diffraction peaks shown in the JCPDS card ICDD #00-033-0041.

In the surface layer 110, the ratio of the particle size of the YAG particles to the particle size of the AlN particles is preferably 0.3 or less. It is believed that the volume resistivity of the surface layer 110 can be reduced by dispersing such fine YAG particles.

The AlN grain boundaries of the ceramic sintered body constituting the bulk layer 120 preferably contain YAP particles or YAM particles, but not YAG particles. This allows the volume resistivity to be maintained relatively high, suppresses leakage current, and makes it easier to control the voltage of the electrodes in the bulk layer. The holding member 100 does not necessarily have to be an electrostatic chuck, and the electrode 150 may be used as an electrode of an RF power source. In the above example, the holding member 100 is composed of only a disk-shaped member, but a shaft may be provided on the opposite side to the substrate mounting surface. It is also preferable to reduce the thermal conductivity of the shaft without using an auxiliary agent.

[Method of manufacturing the holding member]
Next, a method for manufacturing the holding member 100 configured as described above will be described. FIGS. 2(a) to (d) are cross-sectional views each showing a schematic diagram of one stage of the manufacturing process. First, 2 to 6 wt % of Y ₂ O ₃ is added to the AlN raw material, and a PVA-based binder is added to granulate the raw material powder. Then, a plurality of compacts 210, 220a, and 220b are manufactured using the obtained granulated powder. The plurality of compacts 210, 220a, and 220b are degreased at a predetermined temperature or more for a predetermined time or more to manufacture a plurality of degreased bodies. Note that an atmospheric furnace or a nitrogen atmosphere furnace can be used for degreasing, but an atmospheric furnace is preferable because it is important to remove the organic components of the binder.

When degreasing, the conditions differ depending on whether it is a compact corresponding to the surface layer or a bulk layer. For example, it is preferable that the degreased body 310 (first degreased body) placed on the surface side during firing is produced under conditions where the degreasing temperature T1 (°C) and degreasing time H1 (h) satisfy H1 ≥ 300/(T1-540). This results in the surface layer obtained from the degreased body 310 containing YAG particles as impurity particles, but no YAP or YAM particles. As a result, the volume resistivity of the surface layer is reduced, allowing it to exert a strong electrostatic adsorption force on the processing target.

In addition, the degreased body (second degreased body) that is placed on the bulk side, which is opposite the surface side of the first degreased body during firing, is preferably produced under conditions where the degreasing temperature T2 (°C) and degreasing time H2 (h) satisfy H2 < 300/(T2 - 540). As a result, the bulk layer obtained from the degreased body contains YAP particles or YAM particles, which makes it possible to maintain a relatively high volume resistivity, suppress leakage current, and facilitate voltage control of the electrodes. Carbonization of the electrodes can also be suppressed.

Of the multiple degreased bodies, it is preferable that the amount _{of Y2O3} added to the degreased bodies 320a and _320b arranged on the bulk side during firing is greater than the amount of _Y2O3 added to the degreased body 310 arranged on the surface side during firing. This makes it possible to maintain the volume resistivity of the bulk layer obtained from the degreased bodies higher than the volume resistivity of the surface layer.

The electrostatic adsorption electrode 150 is sandwiched between the degreased body 310 and the degreased body 320a obtained in this way, and the heater electrode 160 is sandwiched between the degreased body 320a and the degreased body 320b, and the laminate is hot-pressed and sintered. By embedding the heater electrode 160 at the same time, the electrostatic chuck can be heated to a specific temperature range (200 to 400°C) by self-heating, and in such a temperature range, the volume resistivity of the insulating layer drops to a value sufficient for electrostatic adsorption, allowing a strong adsorption force to be exerted. In addition, this manufacturing method makes it possible to manufacture an electrostatic chuck that can be used in a specific temperature range (200 to 400°C) by self-heating. Note that the installation of the heater electrode 160 can be determined according to the design, and it is not necessarily necessary to provide the heater electrode 160.

Under conventional _degreasing conditions, YAM ( _Y4Al2O9 ) and YAP ( _YAlO3 ) structures are sparsely dispersed at the grain boundaries. However, by performing hot press sintering after sufficient degreasing, the periphery of the AlN particles is ₍ partially) oxidized _{, and the YAG (Y3Al5O12) structure that reacts with Al2O3 and Y2O3 is finely and abundantly dispersed} at the grain boundaries _.

YAG forms a eutectic with Al ₂ O ₃ and between YAG and YAP at a relatively low temperature, so it is easy to incorporate impurities during firing. Therefore, it is presumed that the resistance of the grain boundaries where the YAG phase appears decreases, and the overall volume resistivity decreases. By using this manufacturing method, it is possible to manufacture an electrostatic chuck that can be used in a specific temperature range (200 to 400°C). The electrostatic chuck manufactured in this way can exert a strong electrostatic adsorption force at a specified temperature.

In the above process, the distribution and crystal phase of the double oxide consisting of Al ₂ O ₃ and Y ₂ O ₃ components that is generated at the grain boundaries of the AlN ceramic structure after hot press sintering are adjusted by appropriately degreasing the molded body. As a result, the volume resistivity of the AlN ceramic is appropriately reduced. To achieve this effect, it is preferable to add 2 to 6 wt% of Y ₂ O ₃ , and more preferably 3 to 5 wt%.

[Second embodiment]
In the above embodiment, the bulk layer 120 is formed of a material having different degreasing conditions or composition from the surface layer 110, but the bulk layer 120 may be formed of the same material as the surface layer 110. That is, both the surface layer 110 and the bulk layer 120 can be configured to contain YAG particles in the AlN grain boundaries of the ceramic sintered body, but not to contain YAP particles or YAM particles. By making the surface layer 110 and the bulk layer 120 have the same configuration, the manufacturing process can be simplified.

[Example 1]
Ceramic sintered bodies were produced under different degreasing conditions based on the above-mentioned manufacturing method for the holding member 100, and volume resistivity was measured at each temperature, XRD analysis was performed, and SEM observation of the fracture surface was performed. Details of the raw materials, granulated powder manufacturing method, molding method, molded body processing method, degreasing method, and hot pressing method were in accordance with the methods described in Japanese Patent No. 6148845.

(Samples a1 to a15)
In both _cases , the raw material powder was granulated to prepare a compact, which was made by adding 5 wt% _Y2O3 to the AlN raw material. The compact was then degreased at a predetermined temperature for a predetermined time to prepare a degreased body. Figure 3 is a table showing the degreasing conditions and evaluation results for each sample. The degreasing temperature and degreasing time are as shown in Figure 3. The obtained degreased body was laminated with electrodes sandwiched between them and hot press sintered. SEM observation was performed using the fracture surface of the sample. No polishing or the like was performed. The particle size of the particles other than the AlN phase was determined by photographing the sintered body structure at 2000x or 5000x magnification, and the average of the particle sizes of the top five particles other than the AlN phase in terms of the maximum long axis dimension was used. An X-ray diffraction device (Rigaku MultiFlex Cu Kα 40kV/40mA) was used to confirm the X-ray diffraction peaks during composition evaluation.

(Method of measuring volume resistivity)
The volume resistivity is measured in accordance with JIS C2139. Heat-resistant metal (such as Ni) electrodes are placed on both sides of the ceramic sintered body, a voltage (500 V) is applied between the electrodes, the current is measured, and the volume resistivity is converted from the dimensions of the ceramic sintered body and the electrodes. The measurement can be performed using a microcurrent meter, for example, R8340A manufactured by ADC Co., Ltd. Alternatively, the volume resistivity can be calculated from the current value using a high-voltage power supply and an ammeter.

(Experimental result)
Figures 4(a) and (b) are diagrams in which the volume resistivity and particle size ratio data of each sample are plotted on a graph of degreasing temperature and degreasing time. In Figure 4(a), for example, "4e11" represents 4 x 10 ¹¹ Ωcm. As shown in Figures 4(a) and (b), the threshold equation H = 300/(T-540) expressed using the degreasing temperature T (°C) and the degreasing time H (hours) indicates the degreasing conditions, and classifies the compositions of the obtained samples.

In other words, samples a5, a6, a8 to a10, a12, a13, and a15, which are plotted in the region of H≧300/(T-540), contain YAG particles in the AlN grain boundaries. Samples a1 to a4, a7, a11, and a14, which are plotted in the region of H<300/(T-540), contain YAP or YAM particles in the AlN grain boundaries. Figures 4(a) and (b) show that samples containing YAG particles in the AlN grain boundaries have smaller volume resistivities and particle size ratios than samples containing YAP or YAM particles in the AlN grain boundaries.

Figure 5 is a graph showing the volume resistivity of the surface layer at the measurement temperature. As shown in Figure 5, the higher the degreasing temperature, the lower the volume resistivity after hot press sintering. Also, the longer the degreasing time, the lower the volume resistivity after hot press sintering.

Fig. 6 is a phase diagram of Y ₂ O ₃ -Al ₂ O ₃ system compounds. Referring to Fig. 6, it is considered that the surface layer was degreased sufficiently and then hot press sintered, so that the periphery of the AlN grains was (partially) oxidized, and the structure of YAG (Y ₃ Al ₅ O ₁₂ ) reacted with Al ₂ O ₃ and Y ₂ O ₃ was finely and numerously dispersed at the grain boundaries.

Figure 7 is an SEM photograph showing the fracture surface of each sample (surface layer) with different degreasing conditions. As shown in Figure 7, the crystalline phase of the grain boundary particles in the ceramic structure of samples a9 and a10, which have a reduced volume resistivity, is mainly YAG, with many fine particles (white in the figure) dispersed. The crystalline phase of the grain boundary particles in the ceramic structure of samples a3 and a7, which have not reduced volume resistivity, is mainly YAP, with the particles biased toward larger particles.

The higher the debinding temperature, the lower the volume resistivity after hot press sintering. Also, the longer the debinding time, the lower the volume resistivity after hot press sintering. The crystalline phase of the grain boundaries of the ceramic structure where the volume resistivity was reduced was mainly YAG. The crystalline phase of the grain boundaries of the ceramic structure where the volume resistivity was not reduced was mainly YAP.

[Example 2]
(Samples b1 to b4)
Next, a holding member was produced _and an experiment was conducted to evaluate the electrostatic adsorption force and leakage current. In both cases, a raw material powder in which 5 wt% _Y2O3 was added to an AlN raw material was granulated to produce a compact. The compact for the surface layer (first compact) was degreased at temperature T1 for time H1 to produce a degreased body (first degreased body). Meanwhile, the compact for the bulk layer (second compact) was degreased at temperature T2 for time H2 to produce a degreased body (second degreased body). Temperature T1 was higher than temperature T2, and in both cases was 550°C or higher. The degreasing time was one hour or more in both cases.

In the degreased body for the surface layer or the degreased body for the bulk layer obtained in this way, recesses were formed in which to embed the electrodes for electrostatic attraction and the electrodes for the heater. The electrodes for electrostatic attraction were placed between the degreased bodies for the surface layer or the degreased bodies for the bulk layer, and the electrodes for the heater were sandwiched between the degreased bodies for the bulk layer and stacked. In both cases, Mo mesh (wire diameter 0.1 mm, plain weave, mesh size 50) cut to a specified shape was used as the electrode. The degreased bodies stacked in this way were hot-press sintered.

(Method of measuring electrostatic adsorption force)
An 8-inch silicon wafer was placed on the surface (substrate mounting surface) of the electrostatic chuck, and self-heated by the built-in heater to 300°C in air. After the temperature reached a steady state, 500 V was applied to the electrostatic adsorption electrode, and after 5 seconds, a push-pull gauge was pressed against the side of the silicon wafer. The load at which the silicon wafer began to move was taken as the electrostatic adsorption force. A load of 1000 gf or more was evaluated as ◯, and a load of less than 1000 gf was evaluated as ×. For both the built-in heater and the electrostatic adsorption electrode, electrodes formed inside the sintered body were used.

In all samples, the volume resistivity of the bulk layer was 3×10 ¹² Ωcm, and the volume resistivity of the surface layer was 6×10 ¹⁰ Ωcm or less. Thus, the volume resistivity of the bulk layer was high, the leakage current between the electrostatic attraction electrode and the heater electrode was kept small, and the volume resistivity of the surface layer was low. Therefore, a sufficiently large electrostatic attraction force was exerted even 5 seconds after a voltage was applied to the electrostatic attraction electrode under good temperature control.

(Sample b5)
As the surface layer compact, a raw material powder in which 2 wt% Y ₂ O ₃ was added to the AlN raw material was granulated to produce a plurality of compacts. As the bulk layer compact, a raw material powder in which 5 wt% Y ₂ O ₃ was added to the AlN raw material was granulated to produce a plurality of compacts. Other conditions for the surface layer compact were the same as those for sample a9. The bulk layer compact was the same as those for sample a3. The volume resistivity of the surface layer at this time was 1×10 ¹⁰ Ωcm. The volume resistivity of the bulk layer was 3×10 ^12. As a result, the volume resistivity of the surface layer could be further reduced and the leakage current was suppressed to a small value, so that a sufficiently large electrostatic adsorption force could be exhibited even 5 seconds after a voltage was applied to the electrostatic adsorption electrode under good temperature control.

(Samples b6, b7)
In both _cases , the compacts were produced by granulating raw material powder in which 5 wt% _Y2O3 was added to the AlN raw material. In sample b6, the degreasing conditions for the surface layer compact and the bulk layer compact were 550°C and 4 hours, respectively, and in sample b7, the degreasing conditions for the surface layer compact and the bulk layer compact were 600°C and 4 hours, respectively, so that the degreasing conditions for the surface layer compact and the bulk layer compact were the same. The volume resistivity of the surface layer and the bulk layer was 3 x ¹⁰¹² Ωcm. Because the volume resistivity of the surface layer was high, a high adsorption force was not exhibited 5 seconds after the voltage was applied to the electrostatic adsorption electrode.

The results obtained in this way showed that the higher the debinding temperature, the lower the volume resistivity after hot press sintering. Also, the longer the debinding time, the lower the volume resistivity after hot press sintering. The crystalline phase of the grains at the grain boundaries of the ceramic structure where the volume resistivity was lowered was mainly YAG. The crystalline phase of the grains at the grain boundaries of the ceramic structure where the volume resistivity was not lowered was mainly YAP.

Therefore, it was found that by selecting degreasing conditions that result in different volume resistivities for the surface layer and bulk layer after hot press sintering of the degreased body and maintain a high volume resistivity for the bulk layer, it is possible to produce an AlN electrode-embedded component with suppressed leakage current.

(Sample b8)
The raw material _powder was granulated by adding 5 wt% _Y2O3 to the AlN raw material. Three compacts were then produced from the granulated powder. One of the compacts was degreased at 600°C for 24 hours as a degreased body for the surface layer. The other two compacts were degreased at 550°C for 4 hours as degreased bodies for the bulk layer.

After processing the degreased body for the bulk layer to create recesses for embedding electrodes, an electrode for electrostatic adhesion was sandwiched between the degreased bodies for the surface layer and the bulk layer, and a heater electrode was sandwiched between the degreased bodies for the bulk layer, which were then stacked. The stack was then hot-pressed and sintered at a maximum temperature of 1850°C and 1 MPa in a nitrogen atmosphere. An electrostatic chuck with a built-in heater was produced by processing the exterior and attaching the necessary terminals.

The heater-embedded electrostatic chuck was heated to 300°C by passing electricity through it, and the substrate was placed on the substrate mounting surface. Voltage was then applied to the electrostatic adsorption power supply to perform electrostatic adsorption. The leakage current at this time was less than 1 mA.

(Sample b9)
First, 4 compacts were prepared by granulating the raw material powder obtained by adding 5 wt% _Y2O3 to the AlN raw material. Two of the compacts were degreased at 600°C for ₂₄ hours to prepare two degreased bodies for the surface layer. Meanwhile, the remaining two compacts were degreased at 550°C for 4 hours to prepare degreased bodies for the bulk layer.

After processing the degreased bodies for the surface layer and bulk layer to create recesses for embedding electrodes, the degreased bodies were laminated with an electrode for electrostatic adhesion and an electrode for a heater sandwiched between each other, and hot-pressed in a nitrogen atmosphere at a maximum temperature of 1850°C and 1 MPa. The exterior shape was then processed and the necessary terminals were attached to create an electrostatic chuck with a built-in heater.

The heater of the electrostatic chuck was energized to heat it up and raise its temperature to 300°C. A substrate was placed on the substrate mounting surface and a voltage was applied to the electrostatic adsorption power supply to perform electrostatic adsorption. The leakage current at this time was less than 1 mA.

100 Holding member 110 Surface layer 120 Bulk layer 150 Electrode for electrostatic attraction 160 Electrode for heater 210 Molded body for surface layer 220a, 220b Molded body for bulk layer 310 Degreased body for surface layer (first degreased body)
320a, 320b Degreaser for bulk layer (second degreaser)

Claims (4)

A plate-shaped holding member that is integrally formed and holds the processing object on its surface,
a surface layer and a bulk layer formed of a ceramic sintered body mainly composed of AlN;
an electrode provided between the surface layer and the bulk layer;
the surface layer contains YAG particles at the AlN grain boundaries of the ceramic sintered body, but does not contain YAP particles or YAM particles;
A retaining member, wherein the bulk layer contains YAP particles or YAM particles, but does not contain YAG particles, in the AlN grain boundaries of the ceramic sintered body. The retaining member according to claim 1, characterized in that the ratio of the particle diameter of the YAG particles to the particle diameter of the AlN particles is 0.3 or less. A method for manufacturing a plate-shaped holding member that is integrally formed and holds a processing object on its surface, comprising the steps of:
A step of granulating a raw material powder obtained by adding Y ₂ O ₃ to an AlN raw material to prepare a plurality of compacts;
A step of degreasing the plurality of compacts to produce a plurality of degreased bodies;
and stacking the plurality of degreased bodies with electrodes sandwiched therebetween, and hot-pressing the stacked body.
In the degreasing process, a first degreased body is prepared to be disposed on the surface side during firing under conditions where a degreasing temperature T1 (°C) and a degreasing time H1 (h) satisfy H1≧300/(T1−540);
A method for manufacturing a retaining member, characterized in that in the degreasing treatment step, a second degreased body is produced, the second degreased body being placed on the bulk side, which is opposite the surface side of the first degreased body, during firing, under conditions where a degreasing temperature T2 (°C) and a degreasing time H2 (h) satisfy H2 < 300/(T2 - 540). A method for manufacturing _a retaining member as described in claim 3, characterized in that, among the multiple degreased bodies, the amount of _Y2O3 added to the second degreased body that is placed on the bulk side during firing is greater than the amount of _Y2O3 added to the first _degreased body that is placed on the surface side during firing.

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