JP2019121724A - Substrate tray for plasma treatment - Google Patents

Abstract

To provide a tray with which, when applying plasma treatment while one or a plurality of substrates are placed on the tray, it is possible to apply even treatment to each substrate, and which is usable over a long time.SOLUTION: A tray 20, which is used when placing one or a plurality of substrates to be treated on a tray and applying plasma treatment to the substrates to be treated while the tray is placed in an electrostatic chuck, is constituted by a) a tabular upper member 22 having a hole part 24 for individually accommodating each substrate 30 to be treated and having a thickness that corresponds to the thickness of the substrates 30 to be treated, and b) a tabular lower member 24 placed beneath the upper member 22 and having a durable part 25 composed of a highly plasma resistant material in a top face portion that corresponds to the periphery of the hole part 24. When a substrate 30 to be treated is inserted into each hole part 24 of the upper member 22 of the tray 20 having the upper member 22 and the lower member 23 stacked one on another and plasma treatment is applied, it is unlikely to occur that the tray 20 is eroded by plasma entering from a gap between the periphery of each hole part 24 and the substrate 30 to be treated.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a tray for mounting a substrate on a thin plate-like workpiece (hereinafter referred to as a “substrate”) such as a wafer when performing plasma processing.

  When plasma treatment such as etching or lamination is performed on the surface of a substrate, the substrate needs to be fixed on a substrate table in order to prevent the substrate from moving or deforming during processing. In order to fix the substrate, a suction holding device usually called an electrostatic chuck (ESC) is used. The electrostatic chuck is also provided with a substrate cooling mechanism. This is to prevent the temperature of the substrate from being excessively raised by plasma treatment, damaging the substrate and changing the plasma treatment conditions. The substrate cooling mechanism often comprises a flow path provided in the electrostatic chuck and a cooling medium source for circulating a cooling medium such as helium gas through the flow path.

  When it is necessary to apply plasma treatment uniformly over the entire surface of the substrate, even if the density and temperature of the generated plasma are made uniform over a wide range, the geometrical conditions of the central portion and the peripheral portion of the substrate Because of the difference, differences in plasma throughput, speed, etc. occur. Therefore, a method of providing a ring having the same height as the surface of the substrate to surround the periphery of the substrate and reducing the difference in such plasma processing conditions as much as possible has been developed. For example, Patent Document 1 discloses that a ring called a focus ring is provided around a wafer.

However, since a gap must be provided between the substrate and the focus ring, there is a problem that plasma penetrates from the gap and erodes the electrostatic chuck. In order to solve this, Patent Document 2 discloses that a protective layer made of a material having high plasma resistance such as yttria (Y ₂ O ₃ ) is provided on the lower surface of the gap.

Japanese Patent Laid-Open No. 2002-246370 JP 2017-050468 A JP, 2012-074650, A

  When loading a substrate into a plasma processing chamber or unloading a substrate after processing out of the processing chamber, the substrate is placed on a tray and transported in order to prevent damage to the substrate and improve handling. Processing is often performed while being placed on the Furthermore, in order to enhance processing efficiency, a plurality of substrates may be placed on one tray, a plurality of substrates may be collectively transported by the tray, and processing may be collectively performed in a processing chamber (Patent Literature 3).

  When performing plasma processing on a substrate placed on a tray in a processing chamber, the tray is placed on a substrate table in the processing chamber, and the tray is adsorbed by an electrostatic chuck provided on the substrate table, and The mounted substrate is also indirectly attracted by the electrostatic chuck. In addition, a mechanism for circulating the cooling medium is also provided to the tray.

  As described above, even in the state where the substrate is placed on the tray, it is possible to perform the plasma processing as in the case where only the substrate is placed directly on the electrostatic chuck, but in particular, a plurality of substrates are placed on the tray. In this case, as compared with the case where a single substrate is simply processed, the geometrical configuration in a plan view is complicated, so that processing results are likely to differ between the inside and the periphery of each substrate. Moreover, although the tray is used repeatedly, when the deterioration is severe, the tray can not be used at an early stage, the production efficiency is bad, and the production cost is also increased.

  The problem to be solved by the present invention is that, in the case where plasma processing is performed in a state where one or more substrates are placed on a tray, each substrate is uniformly processed and used for a long time It is to provide a tray that can

The present invention, which has been made to solve the above problems, places one or a plurality of substrates to be treated on a tray and places the tray on an electrostatic chuck with respect to the substrate to be treated. A tray used for plasma treatment,
a) On the upper surface, there are one or more holes having a depth corresponding to the thickness of the substrate to be treated, which accommodates each substrate to be treated individually;
b) A plasma processing apparatus tray characterized in that a durable part having high plasma resistance is provided in a lower part around the respective hole parts.

  In the above, the depth corresponding to the thickness of the substrate to be treated means that the depth is determined by the thickness of the substrate to be treated, and specifically, it is the same as the thickness of the substrate to be treated Sometimes it is shallower (smaller) or deeper (larger). This is set according to the purpose described later.

  Also, the lower portion around each hole is the bottom of the periphery of each hole or below the side of each hole, or both.

  In the tray for a plasma processing apparatus according to the present invention, after the substrate to be processed is inserted into each hole, it is placed on the electrostatic chuck in the plasma processing chamber. Then, after the main tray and the substrate to be processed are adsorbed and fixed by an electrostatic chuck, plasma processing is performed.

  In the tray for a plasma processing apparatus according to the present invention, by making the depth of the holes equal to the thickness of the substrate to be processed, the density and temperature of the plasma inside and around each substrate to be processed can be made substantially uniform. . In addition, by making the depth of the hole shallower or deeper than the thickness of the substrate to be processed, the degree of intentional processing such as making the degree of plasma processing around the substrate to be processed higher or lower than the inside It is also possible to make a difference of

  In the tray for a plasma processing apparatus according to the present invention, since a durable portion having high plasma resistance is provided in the lower part around each hole, the substrate to be processed is inserted into each hole to perform plasma processing. In such a case, the tray is less likely to be corroded by plasma entering from the gap between the periphery of each hole and the substrate to be processed inserted into the hole.

The durable portion in the present invention may be only the lower portion around each hole or may be the entire inside of the hole. Furthermore, it may be the whole tray. The durable portion can be made of, for example, yttria (Y ₂ O ₃ ), quartz, aluminum nitride (AlN), zirconia (ZrO ₂ ) or the like.

Specifically, the tray for a plasma processing apparatus according to the present invention can be in the following mode (first mode). That is,
a) A plate-like upper member having a thickness corresponding to the thickness of the substrate to be treated, having one or more holes for separately accommodating each substrate to be treated;
b) a plate-like member disposed below the upper member, the lower member having a durable portion made of a material having high plasma resistance in a portion corresponding to the periphery of the hole on the upper surface; It can be used as a processing device tray.

  Here, the hole portion of the upper member is a hole which penetrates the upper and lower surfaces of the upper member, unlike the hole portion.

  In the tray for a plasma processing apparatus of the first aspect, the upper member and the lower member may be fixed or separated and may be stacked at the time of use.

  In the tray for a plasma processing apparatus of the first aspect, the durable portion can be formed by providing a groove on the surface of the lower member and filling the groove with a material having high plasma resistance.

  The filling of the material having high plasma resistance can be performed by spraying the material having high plasma resistance in the groove.

The tray for a plasma processing apparatus according to the present invention can also be in the following aspect (second aspect). That is,
a) A material having high resistance to plasma, having a hole for separately accommodating each substrate to be treated, having a thickness corresponding to the thickness of the substrate to be treated, and projecting inward from the periphery of the hole A plate-like upper member having a durable portion comprising
b) A tray for a plasma processing apparatus, comprising: a lower member which is a plate-like member disposed below the upper member.

Yttria (Y ₂ O ₃ ), quartz, aluminum nitride (AlN), or zirconia (ZrO ₂ ) can be used as the material having high plasma resistance.

  In the tray for a plasma processing apparatus according to the present invention, for example, by making the depth of the hole the same as the thickness of the substrate to be processed, the density and temperature of the plasma inside and around each substrate to be processed are approximately equalized. Can. In addition, by making the depth of the hole shallower or deeper than the thickness of the substrate to be processed, the degree of intentional processing such as making the degree of plasma processing around the substrate to be processed higher or lower than the inside It is also possible to make a difference of

  In the tray for a plasma processing apparatus according to the present invention, since a durable portion having high plasma resistance is provided in the lower part around each hole, the substrate to be processed is inserted into each hole to perform plasma processing. In such a case, the tray is less likely to be corroded by plasma entering from the gap between the periphery of each hole and the substrate to be processed inserted into the hole. For this reason, the tray for a plasma processing apparatus according to the present invention can be used in a state of little damage over a long period of time, which can improve the production efficiency and reduce the production cost.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole structure of a plasma processing apparatus. FIG. 2 is a top view of a tray according to an embodiment of the present invention. The center sectional view of the tray of the embodiment. The upper surface figure (a) of the upper member which comprises the tray of the said embodiment, the upper surface figure (b) of a lower member, and center sectional drawing (c) of a lower member. Sectional drawing of the tray which is another 3 types of embodiment. The side view of the tray which is other embodiment, and an electrostatic chuck. The top view of the tray which is other embodiment.

  Hereinafter, a plasma processing apparatus according to the present invention will be described with reference to the attached drawings. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

<1. Overall configuration>
Before describing the tray 20 for the plasma processing apparatus (hereinafter simply referred to as the "tray 20"), the overall configuration of the plasma processing apparatus 10 in which the tray 20 is used will be described with reference to FIG. FIG. 1 is a schematic view showing an entire configuration of a plasma processing apparatus 10. As shown in FIG.

  The plasma processing apparatus 10 includes a vacuum vessel 11 and an upper electrode 12 and a lower electrode 13 provided opposite to the inside thereof. Each of the electrodes 12 and 13 is connected to a high frequency power supply (not shown) for applying a high frequency voltage thereto.

A dielectric layer 14 is provided on the upper surface of the lower electrode 13. On the upper surface of the dielectric layer 14, a tray 20 on which a substrate to be treated (hereinafter simply referred to as a substrate) 30 is mounted is mounted. That is, the upper surface of the dielectric layer 14 constitutes a mounting surface on which the tray 20 is mounted, and the lower electrode 13 and the dielectric layer 14 electrostatically adsorb the tray 20 (electrostatic adsorption device) 15 Configure The electrostatic chuck 15 is a JR force type, and the dielectric layer 14 is made of a low resistance material having a volume resistivity of about 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm. The electrostatic chuck portion 15 may be either a single-pole type or a bipolar type, but the single-pole type can make the adsorption property of the tray 20 particularly good.

  The upper surface of the dielectric layer 14 is provided with a groove 16 for circulating a cooling medium such as helium gas, and the groove 16 is connected to a cooling medium supply device (not shown). The lower electrode 13 is connected to a cooling mechanism 17 for circulating cooling water therein, whereby the lower electrode 13 and the tray 20 are cooled.

  The plasma processing apparatus 10 includes, in addition to the above-described elements, a gas supply unit that supplies various gases and the like for generating plasma in the vacuum vessel 11 and a vacuum exhaust device that exhausts the inside of the vacuum vessel 11 (all not shown) Is equipped.

<2. Tray 20>
The configuration of the tray 20 will be described with reference to FIG. 2, FIG. 3 and FIG. 4 in addition to FIG. 2 is a top view of the tray 20, FIG. 3 is a central cross-sectional view of the tray 20 (III-III cross section of FIG. 2), and FIG. 4 is a top view of the upper member 22 and the lower member 23 constituting the tray 20. And a central cross-sectional view of the lower member 23 (a cross-sectional view taken along a line c-c in FIG. 4B).

<2-1. Overall configuration>
The tray 20 is an apparatus for placing one or a plurality of substrates 30 to be processed by the plasma processing apparatus 10. As shown in FIG. 2, the upper surface of the substrate 30 is shown in FIG. One or more (four in the example of FIG. 2) portions (shown by dotted lines) on which one sheet is placed (hereinafter also referred to as “substrate placement area”) 21 are provided. Each substrate mounting area 21 is an area slightly larger than the substrate 30 in plan view.

  As shown in FIG. 3, the tray 20 in the present embodiment is formed by laminating an upper member 22 and a lower member 23. The upper member 22 and the lower member 23 may be fixed in a stacked state, or may be prepared in a separated state and used by being stacked at the time of plasma processing. In the latter case, it is desirable that a mechanism for positioning the upper member 22 and the lower member 23 be provided on either or both of the upper member 22 and the lower member 23.

  As shown in FIG. 4A, the upper member 22 is a circular flat plate in which a predetermined number (four in the example of FIG. 4) of holes 24 for accommodating one substrate 30 is formed. The lower member 23 is a circular flat plate having the same diameter as that of the upper member 22 as shown in FIG. 4B, and when the upper member 22 is overlapped, a ring shape corresponding to the periphery of the hole 24 is formed. The region is a plasma resistant region 25 corresponding to the durable portion of the present invention. The plasma resistant region 25 is around the substrate 30 when the upper member 22 is placed from outside the hole 24 (indicated by the dotted line inside in FIG. 4B) when the upper member 22 is placed. At the inner side (shown by the dotted line).

In the lower member 23, the plasma resistant region 25 is formed by filling the groove provided in the region with yttria (Y ₂ O ₃ ), which is a material highly resistant to plasma, by thermal spraying. In addition, as the material having high plasma resistance, quartz, aluminum nitride (AlN), zirconia (ZrO ₂ ), or the like can be used.

  By making the thickness of the upper member 22 the same as the thickness of the substrate 30, when the substrate 30 is placed on the substrate placement area 21 of the tray 20, the upper surface of the tray 20 and the upper surface of the substrate 30 become flush. This allows the substrate 30 to be more uniformly processed by plasma.

  The upper member 22 may be configured to cover only the upper surface side of the lower member 23 as shown in FIG. 3 or, as shown in FIG. 5A, in addition to the upper surface side, the side surface of the lower member 23 You may comprise so that it may cover. According to this configuration, the side surface portion of the lower member 23 is not etched by plasma to release impurities. However, the intensity of the plasma in contact with the side surface of the tray 20 is smaller than the intensity of the plasma in contact with the upper surface, 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 member 23 is covered by the upper member 22.

2-2. Forming material>
The lower member 23 in contact with the electrostatic chuck portion 15 of the tray 20 is made of a low volume resistivity material, and the upper member 22 exposed to plasma is made of a high volume resistivity material. The term "low volume resistivity material" as used herein refers to 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 ·· It is a material of cm or less). Moreover, a "high volume resistivity material" said here is a material whose volume resistivity exceeds 1 * 10 < ¹³ > ohm * cm.

The forming material (low volume resistivity material) of the lower member 23 is, for example, a ceramic (in particular, a ceramic containing a large amount of carbon is preferable), and specifically, for example, silicon carbide (SiC). Alternatively, a low resistance aluminum nitride material having a volume resistivity of about 10 ¹¹ Ω · cm can be used as a forming material of the lower member 23. The “low-resistance aluminum nitride material” refers to the volume resistivity of aluminum nitride (volume resistivity is about 10 ¹⁴ Ω · cm) by dispersing a conductive material (conductive additive) such as titanium carbide or carbon fiber. The lower the
Further, as described above, the dielectric layer 14 of the electrostatic chuck portion 15 is formed of a low resistance material having a volume resistivity of about 1 × 10 ⁹ to 1 × 10 ¹² Ω · cm, and the lower member 23 is It is also preferable to form the same material as the material of the dielectric layer 14.

The material forming the upper member 22 (high volume resistivity material) is preferably a material containing a large amount of oxygen, and specifically, for example, alumina (Al ₂ O ₃ ). Alternatively, quartz, aluminum nitride (AlN), yttria (Y ₂ O ₃ ), zirconia (ZrO ₂ ), or the like can be used as a material for forming the upper member 22.

The lower member 23 disposed on the lower surface side of the tray 20 is made of a low volume resistivity material having a volume resistivity of 1 × 10 ¹³ Ω · cm or less, whereby the tray 20 is securely attracted to the electrostatic chuck portion 15 At the same time, the substrate 30 is securely attracted to the tray 20. Thereby, the adhesion between the dielectric layer 14 and the tray 20 and the adhesion between the tray 20 and the substrate 30 are improved, and the heat generated in the substrate 30 and the tray 20 by the plasma processing passes through the tray 20 and the dielectric layer 14. And the lower electrode 13 (outside).

  Further, since the lower member 23 is covered with the upper member 22 made of another material (high volume resistivity material) other than this, for example, a conductive additive for resistance control etc. Even if it is added, it is not released by etching to contaminate the substrate 30.

In particular, here, the upper member 22 is made of a high volume resistivity material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm. That is, although the lower member 23 needs to be made of a material having a relatively low volume resistivity so that the lower member 23 is adsorbed to the electrostatic chuck portion 15, the upper member 22 has no such limitation, and the constituent material thereof Those having a relatively high volume resistivity (specifically, a high volume resistivity material having a volume resistivity exceeding 1 × 10 ¹³ Ω · cm) are acceptable. In this high volume resistivity material, of course, it is not necessary to add a conductive additive for resistance control, and it can be formed from a high purity material. Therefore, even if the upper member 22 is etched, the conductive additive that causes the contamination of the substrate 30 is not released.

  Further, since the upper member 22 does not have such a limitation, it is possible to employ a material having a relatively high etching resistance by plasma, such as yttria exemplified above, as a constituent material of the upper member 22. . By adopting such a material, it is possible to obtain the tray 20 having excellent durability.

According to the present embodiment, since the lower member 23 made of a low volume resistivity material and the upper member 22 made of a high volume resistivity material are formed separably, only the lower member 23 (or only the upper member 22) is replaced. be able to. For example, a plurality of upper members 22 formed of different materials may be prepared, and the optimum upper member 22 may be selected and used according to the process conditions. Also, for example, in the case of a process condition in which the upper member 22 is unnecessary, unnecessary consumption of the upper member 22 can be suppressed by removing the upper member 22 and using only the lower member 23 as a tray.
Alternatively, for example, a plurality of upper members 22 having different sizes and positions of the holes 24 may be prepared, and the optimum upper member 22 may be selected according to the size and the number of substrates 30 to be placed on the tray 20. it can. In this case, the lower member 23 can be a common one.

<2-3. Other configuration example>
In the above embodiment, the hole 24 of the upper member 22 is straight, but as shown in FIG. 5B, the lower surface side of the upper member 22 projects into the hole on the lower surface side. It is also good. In this case, the overhanging portion 26 is the durable portion of the present invention. Furthermore, as in the example of FIG. 5 (a), the upper member 22 may cover the lower member 23 (FIG. 5 (c)).

  When the lower member 23 and the upper member 22 are overlapped to form the tray 20 as described above (in particular, the upper member 22 is not provided with a portion covering the side surface of the lower member 23 (FIGS. 5A and 5C) , It is also preferable to provide an element for aligning the lower member 23 and the upper member 22 and for preventing misalignment. Specifically, for example, one of the lower member 23 and the upper member 22 has an outer peripheral edge thereof. Positioning pins can be provided to be erected at three or more positions.

  In the above embodiment, as shown in FIG. 6, for example, it is also preferable that the substrate mounting area 21 be provided with a cooling passage 27 formed of a groove for circulating a cooling medium. The cooling passage 27 may extend radially from the center of the substrate mounting area 21 as shown in FIG. 7A, or as shown in FIG. 7B, for example. It may be formed along a plurality of circles concentric with the center of the.

  By providing the cooling passage 27 in the tray 20, the substrate 30 placed on the tray 20 can be brought into direct contact with the cooling medium flowing through the cooling passage 27, so that the substrate 30 can be cooled effectively.

  When the cooling passage 27 is provided in the tray 20, it is also preferable to connect the cooling passage 27 to the groove 16 provided on the upper surface of the dielectric layer 14 via the communication passage 28, for example. By so doing, the cooling medium circulated in the groove 16 can be circulated to the cooling passage 27. That is, the cooling medium can flow between the dielectric layer 14 and the tray 20 and between the tray 20 and the substrate 30 in one flow passage. Therefore, the substrate 30 can be efficiently cooled during plasma processing.

  In the above embodiment, the tray 20 has a two-layer structure consisting only of the lower member 23 and the upper member 22. However, the tray 20 may include other layers.

DESCRIPTION OF SYMBOLS 10 Plasma processing apparatus 11 Vacuum container 12 Upper electrode 13 Lower electrode 14 Dielectric layer 15 Electrostatic chuck 16 Groove 17 Cooling mechanism 20 Tray 21 Substrate mounting area 22 Upper member 23 lower part Member 24 ... hole 25 ... plasma resistance region 26 ... overhang portion 27 ... cooling passage 28 ... communicating passage 30 ... substrate

Claims (6)

a) On the upper surface, there are one or more holes having a depth corresponding to the thickness of the substrate to be treated, which accommodates each substrate to be treated individually;
b) A tray for a plasma processing apparatus, wherein a durable portion having high plasma resistance is provided in a portion around each of the hole portions. It is a tray used in the case where the substrate to be processed is to be subjected to plasma processing while one or more substrates to be processed are mounted on a tray and the tray is mounted on an electrostatic chuck,
a) A plate-like upper member having a hole corresponding to the thickness of the substrate to be treated, which has a hole for separately accommodating each substrate to be treated;
b) a plate-like member disposed under the upper member, the lower member having a durable portion made of a material having high plasma resistance on a portion corresponding to the periphery of the hole on the upper surface; A tray for a plasma processing apparatus characterized by   The tray for a plasma processing apparatus according to claim 2, wherein the durable portion is made of a highly plasma resistant material filled in a groove formed in the lower member. The tray for a plasma processing apparatus according to any one of claims 1 to 3, wherein the material having high plasma resistance is yttria (Y ₂ O ₃ ). It is a tray used in the case where the substrate to be processed is to be subjected to plasma processing while one or more substrates to be processed are mounted on a tray and the tray is mounted on an electrostatic chuck,
a) A material having high resistance to plasma, having a hole for separately accommodating each substrate to be treated, having a thickness corresponding to the thickness of the substrate to be treated, and projecting inward from the periphery of the hole A plate-like upper member having a durable edge comprising
b) A tray for a plasma processing apparatus, comprising: a lower member which is a plate-like member disposed below the upper member. The tray for a plasma processing apparatus according to claim 5, wherein the upper member is any one of yttria (Y ₂ O ₃ ), quartz, aluminum nitride (AlN), and zirconia (ZrO ₂ ).

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