JP6664790B2 - Tray for plasma processing equipment - Google Patents

Description

  The present invention relates to a tray for mounting a substrate such as a semiconductor when performing plasma processing on the substrate.

  When performing a process such as etching on a substrate such as a semiconductor, when the substrate is carried into the processing chamber or when the processed substrate is carried out of the processing chamber, the substrate is prevented from being damaged and the handling property is improved. In many cases, the sheet is placed on a tray and conveyed, and the processing is often performed while the sheet is placed on the tray. In order to increase processing efficiency, a plurality of substrates may be placed on a single tray, and a plurality of substrates may be collectively transported by the tray and collectively processed in a processing chamber.

  When plasma processing is performed on a substrate, the temperature of the substrate may increase due to the processing, and processing conditions may change. Further, depending on the substrate, the substrate may be denatured or damaged depending on the temperature. Therefore, in many cases, the substrate is cooled by flowing a cooling medium such as helium gas under the substrate during the plasma processing. Here, in order to effectively transfer the heat of the substrate to the cooling medium, the lower surface of the substrate must be in close contact with the surface of the mounting table through which the cooling medium flows. For this reason, the mounting table is provided with a mechanism for sucking the substrate. In many cases, an electrostatic chuck (electrostatic chuck) that has a simple mechanism and does not generate vibration or the like is used (see Patent Document 1). ).

The electrostatic chuck includes a Coulomb force type and a JR (Johnsen-Rahbek) force type. The former uses a ceramic having a volume resistivity of 1 × 10 ¹⁶ Ω · cm or more, such as high-purity alumina or aluminum nitride, for the dielectric layer. The Coulomb force type has the feature that the time constant required to adsorb and desorb a silicon wafer is short, but it requires the application of a high voltage of 2.0 kV to 3.0 kV to the dielectric layer to obtain the required adsorption force. is there. The JR force type uses a low-resistance dielectric layer with a volume resistivity of about 1 × 10 ⁹ to 1 × 10 ¹² Ωcm, and the time constant required to adsorb and release a silicon wafer is Although it is necessary to consider an appropriate volume resistivity at the time of design at the time of design, the voltage applied to the dielectric layer to obtain the required attraction force may be 1.0 kV or less, which has the advantage of simplifying the power supply configuration. (See Non-Patent Document 1).

JP 2012-074650 JP

Ceramic Society of Japan, Ceramics Museum, "Electrostatic Chuck", [online], July 2008, [Search on June 20, 2016], Internet <URL: http: //www.ceramic.or. jp / museum / contents / pdf / 2008_07_04.pdf>

When a substrate is placed on a tray and plasma processing is to be performed with the substrate placed on the tray, the tray must be attracted by an electrostatic chuck. Therefore, when using a JR force type electrostatic chuck, a tray having a volume resistivity as low as about 1 × 10 ⁹ to 1 × 10 ¹² Ωcm was used, or a conductive pattern was formed on a ceramic tray. You need to use something. In the former case, it is necessary to add a conductive additive such as a metal oxide for resistance control to a ceramic material such as alumina or aluminum nitride in order to reduce the volume resistivity of the dielectric in this way. However, when the substrate is subjected to the plasma processing, the tray is also exposed to the plasma, so that such a conductive additive or the like contained in the tray may be released by the plasma and contaminate the substrate to be processed.

  The problem to be solved by the present invention is to provide a plasma processing apparatus using a JR force type electrostatic chuck, in which a tray that is reliably held by the electrostatic chuck and that releases less impurities during plasma processing is used. To provide.

The present invention made in order to solve the above problems, in a tray for a plasma processing apparatus using a JR force type electrostatic adsorption device,
The lower surface side in contact with the electrostatic adsorption device is made of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less,
A tray characterized in that the upper side exposed to plasma is made of a material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm.

In the tray for a plasma processing apparatus according to the present invention, since the volume resistivity of the material on the lower surface side is 1 × 10 ¹³ Ω · cm or less, the tray is reliably attracted to the electrostatic attracting apparatus. Thereby, the adhesion between the tray mounting table and the tray is improved, and the heat generated in the substrate and the tray by the plasma processing is satisfactorily released to the tray mounting table (outside) through the tray.
Further, since the lower surface side of the tray is covered with a portion made of another material, even if a conductive additive or the like for resistance control is added to the lower surface side, this is not affected. The substrate to be processed is not contaminated by being released by etching (erosion).

In the tray for a plasma processing apparatus according to the present invention, the upper portion, on which one or a plurality of substrates to be processed are placed, is made of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less, and other plasma It is desirable to configure the part exposed to the material with a material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm.
Thereby, the adhesion between the tray and the substrate to be processed is also improved, and the heat generated in the substrate by the plasma processing is better released to the tray mounting table (outside) through the tray.

In this case, it is desirable that only the portion of the tray on which the substrate to be processed is to be settled (settled down) from the upper surface of the tray (so-called “sinking” is performed).
As a result, the separation distance between the upper surface of the substrate to be processed and the upper surface of the tray (that is, the surface made of a material having a volume resistivity of more than 1 × 10 ¹³ Ω · cm) is reduced, and in particular, the counterbore depth is reduced. If the thickness is set to be substantially the same as the thickness of the processing substrate, each of these upper surfaces is flush. This improves the uniformity of the plasma processing.

Such a tray structure is composed of a flat lower layer made of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less and a material having a volume resistivity exceeding 1 × 10 ¹³ Ωcm. A two-layer structure of an upper layer having holes corresponding to the substrate to be processed in a flat plate.
With such a structure, the tray can be easily manufactured.

In the tray for a plasma processing apparatus according to the present invention, it is preferable that a cooling medium circulation passage is provided in a portion of the tray where one or a plurality of substrates to be processed are placed.
Thereby, the substrate comes into direct contact with the cooling medium such as helium gas flowing through the passage, so that the substrate can be cooled better.
It is desirable that the passage for cooling medium distribution on the substrate mounting surface of the tray be communicated with a passage for cooling medium distribution provided on the surface of the tray mounting table or the lower surface of the tray.
This allows the cooling medium to flow through the cooling medium distribution passage between the tray mounting table and the tray and between the tray and the substrate to be processed in one circulation path, and allows the substrate to be processed efficiently during plasma processing. Can be cooled.

In the tray for the plasma processing apparatus according to the present invention, the lower surface side has a volume resistivity of 1 × 10 ¹³ Ωcm or less, so that the tray is securely attracted to the JR force type electrostatic attraction apparatus, and the substrate and the substrate are subjected to the plasma processing. The heat generated in the tray is satisfactorily released to the tray mounting table (outside) through the tray. Further, since the lower surface side of the tray is covered with a portion made of another material, even if a conductive additive or the like for resistance control is added to the lower surface side, this is not affected. The substrate to be processed is not contaminated by being released by etching.

FIG. 1 is a schematic diagram illustrating an overall configuration of a plasma processing apparatus. FIG. 4 is a top view of the tray according to the embodiment. FIG. 3 is a cross-sectional view of the tray according to the embodiment as viewed from an arrow K in FIG. 2. Sectional drawing of the tray which concerns on other embodiment. Sectional drawing of the tray which concerns on other embodiment. The side view of the tray and electrostatic chuck concerning other embodiments. FIG. 14 is a top view of a tray according to another embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments are mere examples embodying the present invention, and do not limit the technical scope of the present invention.

<1. Overall Configuration>
Before describing the tray 10 for a plasma processing apparatus (hereinafter, simply referred to as “tray 10”), an overall configuration of a plasma processing apparatus 100 using the same will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of the plasma processing apparatus 100.

  The plasma processing apparatus 100 includes a vacuum vessel 1 and an upper electrode 2 and a lower electrode 3 provided to face each other. A high-frequency power supply (not shown) for applying a high-frequency voltage thereto is connected to each of the electrodes 2 and 3.

A dielectric layer 4 is provided on the upper surface of the lower electrode 3, and a tray 10 (that is, a tray 10 on which a substrate (substrate to be processed) 9 is mounted) is mounted on the upper surface of the dielectric layer 4. That is, the upper surface of the dielectric layer 4 constitutes a mounting surface on which the tray 10 is mounted, and the lower electrode 3 and the dielectric layer 4 hold the tray 10 by electrostatic chucking (electrostatic chucking device) 5. Is configured. The dielectric layer 4 is a dielectric layer made of a low-resistance material having a volume resistivity of about 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm. That is, the electrostatic chuck section 5 is of the JR force type. The electrostatic chuck unit 5 may be either a monopolar type or a bipolar type. However, if the electrostatic chuck unit 5 is a monopolar type, the adsorption property of the tray 10 can be particularly excellent.

A groove 6 for flowing a cooling medium such as helium gas is provided on the upper surface of the dielectric layer 4, and the groove 6 is connected to a cooling medium supply device (not shown).
The lower electrode 3 is connected to a cooling mechanism 7 for circulating cooling water therein, whereby the lower electrode 3 is cooled.
The plasma processing apparatus 100 includes, in addition to the components described above, a gas supply unit that supplies various gases and the like for generating plasma into the vacuum vessel 1, a vacuum exhaust device that exhausts the inside of the vacuum vessel 1, etc. (Omitted).

<2. Tray 10>
The configuration of the tray 10 will be described with reference to FIGS. 2 and 3 in addition to FIG. FIG. 2 is a top view of the tray 10. FIG. 3 is a sectional view of the tray 10 as viewed from the arrow K in FIG.

<2-1. Overall Configuration>
The tray 10 is a member on which one or more substrates 9 to be processed (hereinafter, simply referred to as “substrates 9”) to be processed by the substrate processing apparatus 100 are placed. One or more portions (hereinafter, also referred to as “substrate mounting regions”) 101 for mounting one substrate 9 are defined (four in the example in the figure). Each substrate mounting area 101 is an area having substantially the same size as the substrate 9 in a plan view (or an area having a slightly larger size than the substrate 9). Each substrate mounting area 101 is sunk (settled) below the upper surface position of the tray 10, thereby forming a spot facing portion 102 of the substrate 9.

  The substrate 9 is loaded into the vacuum vessel 1 in a state where the substrate 9 is mounted on the substrate mounting area 101 on the tray 10 (specifically, in a state where the substrate 9 is disposed in the counterbore 102), and the plasma 9 is generated there. Receive processing. By using the tray 10 in which the plurality of substrate mounting areas 101 are defined, the plurality of substrates 9 can be transported collectively and processed at the same time.

<2-2. Forming Material>
The tray 10 has a multilayer structure including a layer 11 made of a low volume resistivity material and a layer 12 made of a high volume resistivity material (in this embodiment, a two-layer structure composed of only these layers 11 and 12). I have. Specifically, the tray 10 has a lower surface side in contact with the electrostatic chuck portion 5 formed of a layer (hereinafter also referred to as a “lower layer”) 11 made of a low volume resistivity material, and an upper side exposed to plasma has a high level. It is composed of a layer (hereinafter also referred to as “upper layer”) 12 made of a volume resistivity material.
However, the term “low volume resistivity material” as used herein means a material having a volume resistivity of 1 × 10 ¹³ Ω · cm or less (preferably, a volume resistivity of 1 × 10 ⁷ Ω · cm or more and 1 × 10 ¹³ Ω · cm or more. Ω · cm or less). The “high volume resistivity material” here is a material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm.

The material (low volume resistivity material) for forming the lower layer 11 is, for example, a ceramic (particularly, a ceramic containing a large amount of carbon is preferable), and specifically, for example, silicon carbide (SiC). In addition, as a material for forming the lower layer 11, a low-resistance aluminum nitride material having a volume resistivity of about 10 ¹¹ Ω · cm can be used. "Low-resistance aluminum nitride material" refers to the volume resistivity obtained by dispersing a conductive material (conductive additive) such as titanium carbide or carbon fiber in aluminum nitride (volume resistivity is about 10 ¹⁴ Ωcm). Is reduced.
As described above, the dielectric layer 4 is formed of a low-resistance material having a volume resistivity of about 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm. It is also preferable to use the same material as the material.

The material (high volume resistivity material) for forming the upper layer 12 is preferably a material containing a large amount of oxygen, and specifically, for example, alumina (Al ₂ O ₃ ). The others as the material of the upper layer 12, silica, aluminum nitride (AlN), yttria (Y ₂ O _3), zirconia (ZrO _2), or the like can also be used.

The lower layer 11 arranged on the lower surface side of the tray 10 is made of a low volume resistivity material having a volume resistivity of 1 × 10 ¹³ Ω · cm or less, so that the tray 10 At the same time, the substrate 9 is securely sucked to the tray 10. Thereby, the adhesiveness between the dielectric layer 4 and the tray 10 and the adhesiveness between the tray 10 and the substrate 9 are improved, and the heat generated in the substrate 9 and the tray 10 by the plasma processing is transmitted through the tray 10 to the dielectric layer 4. And, it is satisfactorily emitted to the lower electrode 3 (outside).
Further, since the lower layer 11 is covered with the upper layer 12 made of a different material (high volume resistivity material), for example, a conductive additive or the like for controlling the resistance is applied to the lower layer 11. Even if it is added, it is not released by etching and contaminating the substrate 9.
In particular, here, the upper layer 12 is made of a high volume resistivity material whose volume resistivity exceeds 1 × 10 ¹³ Ω · cm. In other words, the lower layer 11 had to be made of a material having a relatively low volume resistivity so that the lower layer 11 was attracted to the electrostatic chuck portion 5, but the upper layer 12 was not limited to such a material. A material having a relatively high volume resistivity (specifically, a high volume resistivity material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm) is acceptable. In this high volume resistivity material, it is needless to say that it is not necessary to add a conductive additive for resistance control, and the material can be formed from a high-purity substance. Therefore, even if the upper layer 12 is etched, the conductive additive that causes contamination of the substrate 9 is not released.
Further, since there is no such limitation in the upper layer 12, it is also possible to adopt a material having relatively high etching resistance by plasma, such as the above-mentioned yttria, as a constituent material of the upper layer 12. . By using such a material, the tray 10 having excellent durability can be obtained.

<2-3. Configuration of Lower Layer 11 and Upper Layer 12>
As described above, the tray 10 has a two-layer structure of the lower layer 11 made of a low volume resistivity material and the upper layer 12 made of a high volume resistivity material.

The lower layer 11 is a thin flat plate-shaped portion having substantially the same size and substantially the same shape as the upper surface of the electrostatic chuck portion 5 in plan view. On the other hand, the upper layer 12 is provided so as to cover an area on the upper surface of the lower layer 11 except for the substrate mounting area 101 described above. That is, holes corresponding to the substrate mounting area 101 are formed in the upper layer 12 of the tray 10.
As described above, in the tray 10, when viewed from above, the entire (or a part) of the portion (substrate mounting region) 101 on which the substrate 9 is mounted is made of the low volume resistivity material, and the other plasma is used. The portion exposed to is composed of a high volume resistivity material. Thereby, the adhesion between the tray 10 and the substrate 9 is improved, and the heat generated in the substrate 9 by the plasma processing is better released to the outside through the tray 10.

Further, by providing the upper layer 12 in an area other than the substrate mounting area 101, a concave portion having the substrate mounting area 101 as a bottom surface is formed on the upper surface of the tray 10, and this constitutes the counterbore portion 102 described above. I do.
By forming the counterbore portion 102, the substrate mounting area 101 is arranged at a relatively low position. Therefore, the distance between the upper surface of the substrate 9 placed on the tray 10 and the upper surface of the tray 10 is reduced. In particular, if the depth of the counterbore portion 102 is set to be approximately the same as the thickness of the substrate 9, each of these upper surfaces will Become flush. Thereby, the substrate 9 mounted on the substrate mounting area 101 is more uniformly processed by the plasma. Further, since the substrate mounting region 101 made of a low volume resistivity material is disposed at a relatively low position, the release of impurities from the substrate mounting region 101 (that is, the lower part of the substrate 9) ( That is, release of impurities caused by etching of the portion by the plasma) can be further reduced.

  The upper layer 12 may be configured to cover only the upper surface side of the lower layer 11 as shown in FIG. 3A, or may be configured to cover the upper surface side as shown in FIG. Thus, the side surface of the lower layer 11 may be configured to be covered. According to the configuration in which the side surface of the lower layer 11 is covered with the upper layer 12, a situation in which the side surface portion of the lower layer 11 is etched by plasma and impurities are released does not occur. However, the intensity of the plasma to which the side surface of the tray 10 is exposed is smaller than the intensity of the plasma to which the upper surface of the tray 10 is exposed, and the side surface is less likely to be etched than the upper surface. Therefore, it is not essential that the side surface of the lower layer 11 is covered with the upper layer 12.

<2-4. Form of Tray 10>
As described above, the tray 10 is configured to include the thin flat plate-shaped lower layer 11 and the upper layer 12 covering only a part of the surface, and the tray 10 is formed separately from the lower layer 11. May be formed by combining the upper layer 12 with the upper layer 12 (first forming mode), or the lower layer 11 and the upper layer 12 may be integrally formed (first mode). 2).

<I. First Form>
The first formation mode will be specifically described.
First, the lower layer 11 is obtained by, for example, baking a low volume resistivity material to form a predetermined thin flat plate shape. On the other hand, the high volume resistivity material is fired, for example, to form a thin flat plate covering the entire upper surface of the lower layer 11 (or a sectional gate shape covering the entire upper surface and the entire side surface of the lower layer 11). I do. Then, holes (through-holes) are formed in the obtained member at each position corresponding to the above-mentioned substrate mounting area 101. Thereby, the upper layer 12 is obtained. By overlaying the upper layer 12 on the lower layer 11, the tray 10 can be obtained.

According to the first formation mode, the lower layer 11 made of the low volume resistivity material and the upper layer 12 made of the high volume resistivity material are formed so as to be separable, so that only the lower layer 11 (or only the upper layer 12) is formed. Can be replaced. For example, a plurality of upper layers 12 made of different materials are prepared, and an optimum upper layer 12 can be selected and used according to the process conditions. Further, for example, in the case of a process condition in which the upper layer 12 is not required, useless consumption of the upper layer 12 can be suppressed by removing the upper layer 12 and using only the lower layer 11 as a tray.
According to the first formation mode, for example, a plurality of upper layers 12 having different hole sizes and formation positions are prepared, and an optimum upper layer 12 is formed according to the size and the number of the substrates 9 to be placed on the tray 10. Layer 12 can be selected. That is, even when the size and the number of the substrates 9 to be placed on the tray 10 are different, the common lower layer 11 can be used.

<Ii. Second Form>
The second formation mode will be specifically described.
First, the lower layer 11 is obtained by, for example, baking a low volume resistivity material to form a predetermined thin flat plate shape. Then, in a region other than the substrate mounting region 101 in the lower layer 11, a high volume resistivity material is sprayed, for example, to form a coating (that is, the upper layer 12) made of the high volume resistance material. Thereby, the tray 10 can be obtained.

According to the second formation mode, when the thickness of the upper layer 12 is reduced due to wear, the thickness of the upper layer 12 is returned to an expected state by spraying a high volume resistivity material or the like again. be able to.
Further, according to the second formation mode, no gap is formed between the lower layer 11 and the upper layer 12 in the tray 10 (or, even if such a gap is formed, the gap becomes very small). Therefore, the thermal conductivity of the tray 10 increases. As a result, heat generated in the substrate 9 and the tray 10 by the plasma processing is satisfactorily released to the outside through the tray 10.
Further, according to the second formation mode, the adjustment of the thickness of the upper layer 12 is easy. Therefore, for example, by making the thickness extremely thin, the entire tray 10 can be made thinner and space efficiency can be improved.
Further, according to the second formation mode, the upper layer 12 can be formed accurately at a predetermined position.

<3. Other Embodiments>
In the above embodiment, the lower layer 11 has a flat upper surface (FIG. 3). However, in the lower layer 11, a region excluding the entire substrate mounting region 101 on the upper surface, or An area excluding a part of the mounting area 101 may be sunk (sunk) from the upper surface position of the other area.
FIG. 4 illustrates a case where a region excluding the entire substrate mounting region 101 is lowered. FIG. 5 illustrates a case where an area excluding a part (here, a central part) of the substrate mounting area 101 is sunk.
According to each of these configurations, the thickness of the upper layer 12 is increased by the depressed width, so that the durability of the tray 10 against plasma is increased.
In particular, according to the configuration illustrated in FIG. 5, a portion (here, a ring-shaped peripheral portion) of the substrate mounting region 101 is configured by the upper layer 12 formed of a high volume resistivity material. . When the substrate 9 is mounted on the substrate mounting area 101, the ring-shaped peripheral portion is not likely to be covered by the substrate 9 (ie, is exposed to plasma). By being formed of the volume resistivity material, it is possible to avoid that the peripheral portion is etched and impurities are released.
In each of the examples shown in FIGS. 4 and 5, the upper layer 12 is configured to cover only the upper surface side of the lower layer 11 as shown in FIGS. 4A and 5A. Alternatively, as shown in FIGS. 4B and 5B, a configuration may be made to cover the side surface of the lower layer 11 in addition to the upper surface side.

In the above embodiment, for example, as shown in FIG. 6, it is also preferable that the substrate mounting area 101 is provided with a cooling passage 103 formed of a groove through which a cooling medium flows. The cooling passage 103 may extend radially from the center of the substrate mounting area 101 as shown in FIG. 7A, for example, or may be mounted on the substrate mounting area as shown in FIG. It may be formed along a plurality of circles arranged concentrically with the center of the region 101.
By providing the cooling passage 103 in the tray 10, the substrate 9 placed on the tray 10 can be brought into direct contact with the cooling medium flowing through the cooling passage 103, so that the substrate 9 can be cooled effectively.

When the cooling passage 103 is provided in the tray 10, it is also preferable that the cooling passage 103 communicates with the groove 6 provided on the upper surface of the dielectric layer 4 via, for example, the communication passage 104.
By doing so, the cooling medium flowing through the groove 6 can be flown to the cooling passage 103. That is, the cooling medium can flow between the dielectric layer 4 and the tray 10 and between the tray 10 and the substrate 9 through one circulation passage. Therefore, the substrate 9 can be efficiently cooled during the plasma processing.

In the above-described embodiment, when the tray 10 is formed by the first formation mode (particularly, when the upper layer 12 is not provided with a portion that covers the side surface of the lower layer 11 (FIG. 3A)), It is also preferable to provide an element for aligning with the upper layer 12 and preventing misalignment.
Specifically, for example, one of the lower layer 11 and the upper layer 12 (for example, the lower layer 11) may be provided with a positioning pin that stands up to three or more positions on the outer peripheral edge thereof. According to this configuration, in a state where the upper layer 12 is put on the lower layer 11, the positioning pins abut on the side surfaces of the upper layer 12, thereby positioning the portions 11 and 12.
In this case, it is also preferable to provide a mark such as a scribe mark at a position corresponding to the positioning pin on the outer peripheral edge of the portion where the positioning pin is not erected. According to this configuration, the rotational positions of both portions 11, 12 can be aligned by aligning the positioning pins with the mark positions.

  In the above embodiment, the tray 10 has a two-layer structure including only the lower layer 11 and the upper layer 12, but the tray 10 may include other layers.

Reference Signs List 100 plasma processing apparatus 1 vacuum vessel 2 upper electrode 3 lower electrode 4 dielectric layer 5 electrostatic chuck section 6 groove 7 cooling mechanism 9 substrate 10 plasma processing tray (tray)
11 Lower layer 12 Upper layer 101 Substrate mounting area 102 Counterbore 103 Cooling passage 104 Communication path

Claims (5)

A tray for a plasma processing device using a JR force type electrostatic adsorption device,
The lower surface side in contact with the electrostatic adsorption device is made of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less,
The upper side exposed to the plasma was made of a material whose volume resistivity exceeded 1 × 10 ¹³ Ωcm.
tray. The tray according to claim 1,
The upper portion, on which one or more substrates to be processed are placed, is made of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less, and the other portions exposed to plasma have a volume resistivity of 1 ×. Composed of a material exceeding 10 ¹³ Ωcm
tray. 3. The tray according to claim 2 , wherein
The portion on which the substrate to be processed is placed is sinking from the upper surface of the tray,
tray. 4. The tray according to claim 3, wherein
A flat lower layer composed of a material having a volume resistivity of 1 × 10 ¹³ Ωcm or less,
An upper layer made of a material having a volume resistivity exceeding 1 × 10 ¹³ Ωcm, and having a flat plate having holes corresponding to the substrate to be processed,
Comprising a tray. The tray according to claim 2 , wherein:
In a portion where the substrate to be processed is mounted, a passage for cooling medium circulation is provided.
tray.

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