JP2024058161A - Susceptor - Google Patents

Abstract

To provide a heat-resistant susceptor that can be usable at high temperatures, such as above 200°C.SOLUTION: A susceptor 100 includes a disc-shaped sintered ceramic body 110 made mainly of SiC and a plate-shaped metal body 120 embedded in the sintered ceramic body 110. The thickness (length in a vertical direction 5) of the metal body 120 is 0.1 mm or more. The metal body 120 is embedded at a distance of at least 0.05 mm below a top surface 111 of the sintered ceramic body 110.SELECTED DRAWING: Figure 2

Description

The present invention relates to a susceptor that holds a substrate such as a silicon wafer.

Patent Document 1 discloses a susceptor for holding a substrate such as a wafer. The susceptor disclosed in Patent Document 1 includes a ceramic sintered body (substrate support) on which the substrate is placed, and a metal body (RF plate) embedded to a depth of 0.2 mm to 50 mm from the surface. In the susceptor disclosed in Patent Document 1, the ceramic sintered body is made of aluminum nitride (AlN) or alumina (Al ₂ O ₃ ).

JP 2008-300832 A

Traditionally, susceptors have been made of Al alloys such as AlN, due to their ease of processing, high thermal conductivity, and ability to double as high-frequency electrodes. However, due to the heat resistance of the Al alloy itself, there were limitations to their use at high temperatures exceeding 200°C. With the recent trend toward higher power semiconductor processes, there is a demand for susceptors with high heat resistance.

The present invention was made in consideration of these circumstances, and aims to provide a highly heat-resistant susceptor that can be used at high temperatures exceeding 200°C.

According to an aspect of the present invention, there is provided a disk-shaped ceramic sintered body having an upper surface and a lower surface vertically opposed to the upper surface, the disk-shaped ceramic sintered body being mainly composed of SiC;
a plate-shaped metal body embedded in the ceramic sintered body and having a length of 0.1 mm or more in the vertical direction;
The susceptor is characterized in that the metal body is embedded at a position 0.05 mm or more below the upper surface of the ceramic sintered body.

The metal body is embedded at a position 0.05 mm or more below the upper surface of the ceramic sintered body, so that the metal body can be used as a high-frequency electrode or a heater electrode. Since the thickness of the metal body is 0.1 mm or more, the strength of the metal body can be increased. Furthermore, by making the thickness (length in the vertical direction) of the metal body 0.1 mm or more, the impedance can be kept small. This is particularly effective when the metal body is used as a high-frequency electrode. Generally, the operating temperature of a susceptor made of an Al alloy is about 100°C to 200°C. In contrast, in the susceptor of the present invention, the ceramic sintered body is formed by sintering a ceramic material mainly composed of SiC, which has a higher melting point than an Al alloy, so that it can be used at high temperatures of 500°C or more.

FIG. 1 is a perspective view of a susceptor 100 . FIG. 2 is a schematic diagram of the susceptor 100. As shown in FIG. FIG. 3 is a schematic explanatory diagram of the metal body 120. 1A to 1D are diagrams showing the flow of a manufacturing method (calcined body bonding method) for a ceramic sintered body 110. 11A to 11D are diagrams showing the flow of another manufacturing method (powder hot pressing method) of the ceramic sintered body 110. FIG. 6 is a table summarizing the results of Examples 1 to 6.

<Susceptor 100>
A susceptor 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. The susceptor 100 according to this embodiment is used, for example, as a stage for holding a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as a wafer 10) inside a semiconductor manufacturing device, or as a stage for holding another susceptor. In the following description, the up-down direction 5 is defined based on a state in which the susceptor 100 is installed so as to be usable (the state shown in Figure 1). As shown in Figure 1, the susceptor 100 according to this embodiment includes a ceramic sintered body 110, a metal body 120 (see Figures 2 and 3), and wiring 140 (see Figure 2).

The ceramic sintered body 110 is a member having a circular plate shape with a diameter of about 400 mm, and the wafer 10 is placed on the upper surface 111 of the ceramic sintered body 110. The thickness (length in the vertical direction 5) of the ceramic sintered body 110 is preferably 10 mm to 50 mm. In FIG. 1, the wafer 10 and the ceramic sintered body 110 are shown separated from each other to make the drawing easier to see. As shown in FIG. 2, a first flow path 162, which will be described later, is formed inside the ceramic sintered body 110. The ceramic sintered body 110 is formed of a ceramic sintered body containing silicon carbide (SiC) as a main component. Here, containing SiC as a main component means containing 90 wt% or more of SiC. In addition, a sintering aid containing boron (B) as a component (sintering aid of B component) and/or a sintering aid containing carbon (C) as a component (sintering aid of C component) may be added to the ceramic sintered body containing SiC as a main component. The sintering aid of component B and the sintering aid of component C may each be added at a concentration of 5 wt % or less. In addition, an Al compound such as Al ₂ O ₃ , Al ₂ O ₃ --Y ₂ O ₃ , or AlB ₂ may be added at a concentration of 5 wt % or less to a ceramic sintered body containing SiC as a main component.

As shown in FIG. 2, the metal body 120 is embedded in the ceramic sintered body 110 at a position 0.05 mm or more below the upper surface 111. As described below, the metal body 120 is a sintered metal body that is sintered simultaneously with the ceramic sintered body 110, which is mainly composed of SiC. As shown in FIG. 3, the metal body 120 has a circular shape. The diameter of the metal body 120 is 300 mm, and it is not exposed from the side of the ceramic sintered body 110. A terminal portion 121 that is connected to the wiring 140 (see FIG. 2) is provided approximately in the center of the metal body 120. In this embodiment, the metal body 120 functions as a high-frequency electrode.

The metal body 120 is formed of tungsten (W) or molybdenum (Mo), or an alloy containing molybdenum and/or tungsten. The purity of these metals or alloys is preferably 99% or more. From the viewpoint of reducing the difference in linear expansion coefficient with SiC and reducing residual stress after sintering, tungsten (W) is particularly preferable.

The metal body 120 can be formed from a dense metal bulk body (such as a metal foil) formed by powder metallurgy or rolling, a mesh woven from metal wires, or a porous metal body. When the metal body 120 is formed from a porous body, the porosity is preferably 40 to 90%, and more preferably 50 to 75%. The pore size is preferably 50 to 1000 μm. The thickness of the metal body 120 after firing is 0.1 mm or more and 10 mm or less. The thickness of the metal body 120 is more preferably 1 mm or more and 5 mm or less. It is preferable that the thickness of the metal body 120 is uniform, but the thickness does not have to be uniform. In that case, the maximum thickness of the metal body 120 is the thickness of the metal body 120. In this embodiment, the metal body 120 has a circular shape as shown in FIG. 3, but the shape of the metal body 120 is not limited to this and can be changed as appropriate. In addition to or instead of the metal body 120 serving as a high-frequency electrode, another metal body may be embedded inside the ceramic sintered body 110. For example, a heating resistor (heater electrode) may be embedded as the other metal body.

2, a first flow path 162 is formed inside the ceramic sintered body 110. The first flow path 162 extends so as to draw a double circle concentric with the disc-shaped ceramic sintered body 110. An inlet port 162a is provided at one end of the first flow path 162, and an outlet port 162b is provided at the other end. The inlet port 162a and the outlet port 162b are formed as through holes extending in the up-down direction 5 from the lower surface 113 of the ceramic sintered body 110 to the first flow path 162. A refrigerant can be flowed through the first flow path 162 via the inlet port 162a and the outlet port 162b. The refrigerant flowing through the first flow path 162 may be a liquid or a gas. For example, water, alcohol, etc. can be used as the refrigerant. The main component of the ceramic sintered body used in a general susceptor is often aluminum nitride (AlN), but since AlN reacts with water, it is not possible to form a refrigerant flow path inside the ceramic sintered body and directly flow cooling water, as in this embodiment. In contrast, the ceramic sintered body 110 of the susceptor 100 of this embodiment contains SiC as its main component. Since SiC does not react with water, it is possible to directly pass cooling water through the first flow path 162 formed inside the ceramic sintered body 110.

As shown in FIG. 2, inside the ceramic sintered body 110, there are arranged wiring 140 connected to the metal body 120 and a temperature sensor 141 such as a thermocouple. Although only one wiring 140 is shown in FIG. 2, multiple wirings 140 can be provided. The upper end of the wiring 140 is electrically connected to the metal body 120. A temperature sensor is provided at the upper end of the temperature sensor 141, and is arranged inside the ceramic sintered body 110.

Next, a method for manufacturing the susceptor 100 will be described. First, a calcined body joining method will be described as a method for manufacturing the ceramic sintered body 110. Note that, for the sake of simplicity, it is assumed that one metal body 120 is embedded inside the ceramic sintered body 110. In addition, in the following description, an example is given in which three calcined bodies are produced and stacked, but the present invention is not limited to such an embodiment, and two or four or more calcined bodies may be produced and stacked.

As shown in FIG. 4(a), the SiC granulated powder P is mixed with a binder such as a thermosetting resin binder and a sintering aid, and then CIP molded and processed into a disk shape to produce three SiC molded bodies 610a, 610b, and 610c. The SiC granulated powder P preferably contains 5 wt% or less of a sintering aid of the B component and/or 5 wt% or less of a sintering aid of the C component. The SiC granulated powder P is preferably high in purity, and its purity is preferably 96% or more, more preferably 98% or more. The average particle size of the SiC granulated powder is preferably 0.1 μm or more and 1.0 μm or less, more preferably 0.3 μm or more and 0.8 μm or less. The mixing method may be either wet or dry.

Next, as shown in FIG. 4(b), the SiC molded bodies 610a to 610c are heated at a temperature of 900°C or more and less than 1200°C to perform a degreasing process, and after removing the binder, are heated at a temperature of 1200°C or more and 1900°C or less to produce the SiC calcined bodies 611a to 611c. The SiC molded bodies 610a to 610c may be heated while being continuously heated to a temperature of 1200°C or more and 1900°C or less to produce the SiC calcined bodies 611a to 611c. Alternatively, the degreased bodies obtained by degreasing the SiC molded bodies 610a to 610c may be used as the SiC calcined bodies 611a to 611c.

Next, as shown in FIG. 4(c), a recess 612 that will become the first flow path 162 is formed in the SiC calcined body 611c, a recess 613 for embedding the metal body 120 is formed in the SiC calcined body 611b, and the metal body 120 is placed in the recess 613. The SiC calcined body 611b with the recess 613 formed therein is stacked on the SiC calcined body 611c with the recess 612 formed therein, and the SiC calcined body 611a is further stacked on top of that. Note that the recesses 612 and 613 may be formed in the molded bodies 610c and 610b beforehand.

Next, as shown in FIG. 4(d), the SiC calcined bodies 611a to 611c stacked so as to sandwich the metal body 120 are pressed and fired at a temperature of 2000°C to 2200°C to produce the fired body 615. The pressure applied during firing is preferably 1 MPa or more. The firing time is preferably 0.1 hours to 10 hours, more preferably 1 hour to 5 hours.

After producing the sintered body 615, blind hole processing is performed up to the metal body 120 to form an insertion hole for inserting the wiring 140. Similarly, blind hole processing is performed to form an insertion hole for inserting the temperature sensor 141. Furthermore, through holes are formed to become the inlet port 162a and outlet port 162b of the first flow path 162. This makes it possible to produce a ceramic sintered body 110 with the first flow path 162 formed inside.

If the first flow path 161 is not formed inside the ceramic sintered body 110, the ceramic sintered body 110 can be produced by the powder hot pressing method described below.

As shown in FIG. 5(a), granulated powder P mainly composed of SiC powder is put into a bed-type mold 501 made of carbon and pre-pressed with a punch 502. The granulated powder P preferably contains 5 wt% or less of a sintering aid of B component and/or 5 wt% or less of a sintering aid of C component. Next, as shown in FIG. 5(b), a metal body 120 is placed on the pre-pressed granulated powder P. The metal body 120 is placed so as to be parallel to a surface perpendicular to the pressure direction (the bottom surface of the bed-type mold 501). At this time, W pellets or Mo pellets may be embedded in a position where they overlap with the wiring 140 of the metal body 120 (see FIG. 3).

As shown in FIG. 5(c), granulated powder P is further poured into bed-type mold 501 so as to cover metal body 120, and pressed and molded with punch 502. Next, as shown in FIG. 5(d), granulated powder P with metal body 120 embedded therein is fired in a pressed state to produce a fired body. It is preferable that the pressure applied during firing is 1 MPa or more. It is also preferable that firing is performed at a temperature of 1800°C or more. The process after producing the fired body is the same as the process described above, so a description thereof will be omitted.

The present invention will be further explained below using Examples 1 to 6. However, the present invention is not limited to the examples described below. Figure 6 shows a table summarizing the results of Examples 1 to 6.

[Example 1]
The susceptor 100 (see FIG. 2) of Example 1 will be described. In Example 1, a ceramic sintered body 110 having a diameter of 400 mm and a thickness of 45 mm was produced by the above-mentioned calcined body bonding method using granulated powder of silicon carbide (SiC) to which _0.5 wt % of B4C and 4 wt % of C were added as a raw material. A circular tungsten foil having a thickness of 0.1 mm and a diameter of 300 mm (see FIG. 3) was used as the metal body 120.

The SiC compacts 610a to 610c were calcined under normal pressure in argon gas at a temperature of 1700°C for a calcination time of 3 hours. The SiC calcined bodies 611a and 611b were processed to have a diameter of 400 mm and a thickness of 10 mm, and the SiC calcined body 611c was processed to have a diameter of 400 mm and a thickness of 25 mm. The depth of the recess 613 formed in the SiC calcined body 611b was 0.1 mm, the same as the thickness of the metal body 120. The diameter of the recess 613 was 302 mm. The width of the recess 162 formed in the SiC calcined body 611c was 20 mm and the depth was 15 mm. The calcined SiC bodies 611a to 611c were calcined under a temperature of 2070°C and a pressure of 2.45 MPa. By firing under such firing conditions, it was possible to produce a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated within the ceramic sintered body 110. In other words, it was possible to directly bond the SiC ceramic and the metal body 120 inside the ceramic sintered body 110 without using a bonding agent or the like. In addition, even when water was circulated as a coolant through the first flow path 162, no problems such as water leakage occurred.

[Example 2]
The susceptor 100 of Example 2 was manufactured by the same manufacturing method as the susceptor 100 of Example 1, except that the thickness of the metal body 120 was set to 0.3 mm, and the depth of the recess 613 formed in the SiC calcined body 611b was set to 0.3 mm, which is the same as the thickness of the metal body 120. As in Example 1, it was possible to manufacture a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated within the ceramic sintered body 110, that is, a susceptor 100 in which the SiC ceramic and the metal body 120 were directly bonded to each other without using a bonding agent or the like within the ceramic sintered body 110. Furthermore, even when water was circulated as a coolant through the first flow path 162, no problems such as water leakage occurred.

[Example 3]
The susceptor 100 of Example 3 was manufactured by the same manufacturing method as the susceptor 100 of Example 1, except that the thickness of the metal body 120 was set to 1 mm, and the depth of the recess 613 formed in the SiC calcined body 611b was set to 1 mm, which is the same as the thickness of the metal body 120. As in Example 1, it was possible to manufacture a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated within the ceramic sintered body 110, that is, a susceptor 100 in which the SiC ceramic and the metal body 120 were directly bonded to each other without using a bonding agent or the like within the ceramic sintered body 110. Furthermore, even when water was circulated as a coolant through the first flow path 162, no problems such as water leakage occurred.

[Example 4]
The susceptor 100 of Example 4 was manufactured by the same manufacturing method as the susceptor 100 of Example 1, except that the thickness of the metal body 120 was set to 5 mm, and the depth of the recess 613 formed in the SiC calcined body 611b was set to 5 mm, which is the same as the thickness of the metal body 120. As in Example 1, it was possible to manufacture a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated within the ceramic sintered body 110, that is, a susceptor 100 in which the SiC ceramic and the metal body 120 were directly bonded to each other without using a bonding agent or the like within the ceramic sintered body 110. Furthermore, even when water was circulated as a coolant through the first flow path 162, no problems such as water leakage occurred.

[Example 5]
The susceptor 100 of Example 5 was manufactured by the same manufacturing method as the susceptor 100 of Example 1, except that a molybdenum mesh (a plain weave of molybdenum wire with a wire diameter of 0.1 mm, mesh size 50) was used as the metal body 120, and the depth of the recess 613 formed in the SiC calcined body 611b was set to 0.1 mm, which is the same as the thickness of the metal body 120. As in Example 1, a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated in the ceramic sintered body 110, that is, a susceptor 100 in which the SiC ceramic and the metal body 120 were directly bonded to each other without using a bonding agent or the like, could be manufactured. Furthermore, even when water was circulated as a coolant in the first flow path 162, no problems such as water leakage occurred.

[Example 6]
The susceptor 100 of Example 6 was produced by the same manufacturing method as the susceptor 100 of Example 1, except that a tungsten porous body (porosity 40%) having a thickness of 5 mm was used as the metal body 120, and the depth of the recess 613 formed in the SiC calcined body 611b was set to 3.5 mm, which is 70% of the thickness of the porous body. As in Example 1, a susceptor 100 in which the SiC ceramic and the metal body 120 were sintered and integrated in the ceramic sintered body 110, that is, a susceptor 100 in which the SiC ceramic and the metal body 120 were directly bonded to each other without a bonding agent or the like, was produced. Since the depth of the recess 613 was set to 70% of the thickness of the porous body, the porous body could be densified by the pressure applied during firing. In addition, since a porous body was used as the metal body 120, SiC penetrated into some of the pores of the porous body during firing, and it was possible to firmly bond the SiC to the metal body 120. Furthermore, even when water was circulated as a coolant through the first flow path 162, no problems such as water leakage occurred.

<Effects of the embodiment>
In the above embodiment and examples 1 to 6, the susceptor 100 includes a disk-shaped ceramic sintered body 110 mainly composed of SiC, and a plate-shaped metal body 120 embedded in the ceramic sintered body 110. The fact that the main component is SiC means that the ratio of SiC to the ceramic material constituting the ceramic sintered body 110 is 90 wt % or more. The thickness (length in the vertical direction 5) of the metal body 120 is 0.1 mm or more. The metal body 120 is embedded at a position 0.05 mm or more below the upper surface 111 of the ceramic sintered body 110.

Since the metal body 120 is embedded at a position 0.05 mm or more below the upper surface 111 of the ceramic sintered body 110, the metal body 120 can be used as a high-frequency electrode or a heater electrode. Since the thickness of the metal body 120 is 0.1 mm or more, the strength of the metal body 120 can be increased. Furthermore, by making the thickness of the metal body 120 0.1 mm or more, the impedance can be kept small. This is particularly effective when the metal body 120 is used as a high-frequency electrode. The thickness of the metal body 120 can be 3 mm or more, and can also be 5 mm or more.

Generally, the operating temperature of an Al alloy susceptor is approximately 100°C to 200°C. In contrast, in the susceptor 100 of this embodiment, the ceramic sintered body 110 is formed by sintering a ceramic material whose main component is SiC, which has a higher melting point than an Al alloy, so it can be used at high temperatures of 200°C or higher.

In the above embodiment and Examples 1 to 6, the ceramic sintered body 110 and the metal body 120 are directly bonded inside the ceramic sintered body 110. In other words, the ceramic sintered body 110 and the metal body 120 are integrated by sintering. Therefore, heat resistance can be improved compared to when the ceramic sintered body 110 and the metal body 120 are integrated with an organic adhesive or other low-melting point bonding agent.

The wafer 10 can be placed directly on the upper surface 111 of the susceptor 100. Alternatively, the wafer 10 can be placed on the upper surface 111 of the susceptor 100 via another susceptor. In the above embodiment and Examples 1 to 6, a first flow path 162 is formed inside the ceramic sintered body 110. By flowing a coolant adjusted to a predetermined temperature through the first flow path 162, the heat of the susceptor 100 can be removed. This makes it possible to adjust the temperature of another susceptor or the wafer 10 placed on the upper surface 111 of the susceptor 100. In addition, since the ceramic sintered body 110 is mainly composed of SiC, it is not reactive with water. Therefore, water can be flowed as a coolant through the first flow path 162 formed inside the ceramic sintered body 110.

In the above embodiment and Examples 1 to 6, the metal body 120 contains at least one metal selected from W, Mo, and an alloy of W and Mo as a main component. When these metals are used as the metal body 120, the difference between the linear expansion coefficient of the metal body 120 and the linear expansion coefficient of SiC can be made smaller than when other metals are used. This makes it possible to reduce the residual stress remaining inside the ceramic sintered body 110 after sintering, thereby suppressing the occurrence of breakage when the susceptor 100 is used repeatedly for a long period of time. Among W, Mo, and an alloy of W and Mo, the difference between the linear expansion coefficient of W and the linear expansion coefficient of SiC is the smallest. Therefore, from the viewpoint of reducing the difference between the linear expansion coefficient of the metal body 120 and the linear expansion coefficient of SiC, it is preferable to use W as the metal body 120.

In Example 6 above, the metal body 120 was a porous body. In this case, the porous body becomes dense by applying pressure during sintering, and SiC penetrates into some of the pores of the porous body during firing, so that the SiC and the metal body 120 can be firmly bonded.

<Modification>
The above-described embodiment is merely an example and may be modified as appropriate. For example, the shape and dimensions of the ceramic sintered body 110 are not limited to those in the above-described embodiment and may be modified as appropriate.

In the above embodiment, molybdenum, tungsten, or an alloy containing molybdenum and/or tungsten is used as the metal body 120, but the present invention is not limited to such an embodiment. For example, metals or alloys other than molybdenum and tungsten can also be used. Also, in the above embodiment, the number of metal bodies 120 is one. However, the present invention is not limited to such an embodiment, and multiple metal bodies 120 may be embedded in the ceramic sintered body 110.

The above describes the embodiment of the invention and its modified forms, but the technical scope of the present invention is not limited to the scope of the above description. It will be clear to those skilled in the art that various modifications and improvements can be made to the above embodiment. It is also clear from the claims that forms with such modifications or improvements can be included in the technical scope of the present invention.

The order of execution of each process in the manufacturing method shown in the specification and drawings is not specifically stated, and the processes may be executed in any order unless the output of a previous process is used in a subsequent process. For convenience, even if the description uses "first," "next," etc., it does not mean that the processes must be executed in that order.

100 susceptor 110 ceramic sintered body 120 metal body

Claims (6)

a disk-shaped ceramic sintered body having an upper surface and a lower surface facing the upper surface in the vertical direction, the disk-shaped ceramic sintered body being mainly composed of SiC;
a plate-shaped metal body embedded in the ceramic sintered body and having a length of 0.1 mm or more in the vertical direction;
The susceptor is characterized in that the metal body is embedded at a position 0.05 mm or more below the upper surface of the ceramic sintered body. The susceptor according to claim 1, in which the ceramic sintered body and the metal body are directly bonded. The susceptor according to claim 1, wherein the ceramic sintered body includes a flow path formed therein. The susceptor according to claim 2, wherein the ceramic sintered body includes a flow path formed therein. The susceptor according to any one of claims 1 to 4, wherein the metal body contains at least one metal selected from the group consisting of W, Mo, and an alloy of W and Mo as a main component. The susceptor according to claim 5, wherein the metal body is a porous body.

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