JP6981652B2 - Substrate tray for plasma processing - Google Patents

Description

The present invention relates to a tray on which a thin plate-shaped material to be treated such as a wafer (hereinafter, referred to as "a substrate") is subjected to plasma treatment and the substrate is placed.

When plasma treatment such as etching or lamination is applied to the surface of a substrate, it is necessary to fix the substrate on a substrate base so that the substrate does not move or deform during the treatment. A suction holding device called an electrostatic chuck (ESC) is usually used for fixing the substrate. 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 the plasma treatment, damaging the substrate, and changing the plasma treatment conditions. In many cases, this substrate cooling mechanism 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 evenly to 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 part and the peripheral part of the substrate will be met. Since there is a difference, there is a difference in the amount of plasma processed, the speed, and the like. Therefore, a method has been developed in which a ring having the same height as the surface of the substrate is provided so as to surround the periphery of the substrate, and the difference in such plasma processing conditions is minimized. For example, Patent Document 1 discloses that a ring called a focus ring is provided around a wafer.

However, since there is no choice but to provide a gap between the substrate and the focus ring, there is a problem that plasma invades through the gap and erodes the electrostatic chuck. In order to solve this problem, Patent Document 2 discloses that a protective layer made of a material having high plasma resistance such as _{ytria (Y 2} O _{3) is provided on the lower surface of the gap.}

Japanese Unexamined Patent Publication No. 2002-246370 Japanese Unexamined Patent Publication No. 2017-050468 Japanese Unexamined Patent Publication No. 2012-074650

In order to prevent damage to the substrate and improve handleability when the substrate is carried into the plasma processing chamber or the processed substrate is carried out from the processing chamber, the substrate is placed on a tray and transported, and also on the tray. In many cases, the processing is performed while it is placed on the screen. Further, in order to improve the processing efficiency, it is also possible to place a plurality of substrates on one tray, transport the plurality of substrates together in the tray, and perform the processing collectively in the processing chamber (patented). Document 3).

When the substrate placed on the tray is subjected to plasma treatment in the processing chamber, the tray is placed on the substrate base in the processing chamber, the tray is attracted by the electrostatic chuck provided on the substrate base, and the tray is placed on the tray. The mounted substrate is also indirectly attracted by the electrostatic chuck. In addition, the tray is also provided with a mechanism for distributing the cooling medium.

In this way, even when the substrate is placed on the tray, plasma treatment can be performed in the same manner as when only the substrate is directly placed on the electrostatic chuck, but in particular, a plurality of substrates are placed on the tray. In this case, the geometrical configuration in a plan view is more complicated than in the case of simply processing one substrate, so that the processing result tends to differ between the inside and the periphery of each substrate. In addition, the tray is used repeatedly, but if the deterioration is severe, the tray becomes unusable at an early stage, resulting in poor production efficiency and an increase in production cost.

The problem to be solved by the present invention is that when one or more substrates are placed on a tray and plasma treatment is performed, each substrate is uniformly treated and used for a long period of time. It is to provide a tray that can be used.

In the present invention made to solve the above problems, one or a plurality of substrates to be processed are placed on a tray, and the tray is placed on an electrostatic chuck with respect to the substrate to be processed. This tray is used for plasma processing.
a) The upper surface has one or more holes having a depth corresponding to the thickness of the substrate to be processed, which individually accommodates each substrate to be processed.
b) This is a tray for plasma processing equipment, characterized in that a durable portion having high plasma resistance is provided in the lower portion around each of the holes.

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

Further, the lower portion around each hole portion is the bottom portion around each hole portion, the lower portion of the side portion of each hole portion, or both of them.

The tray for a plasma processing apparatus according to the present invention is placed on an electrostatic chuck in a plasma processing chamber after a substrate to be processed is inserted into each hole. Then, after adsorbing and fixing the tray and the substrate to be processed with an electrostatic chuck, plasma processing is performed.

In the plasma processing apparatus tray according to the present invention, by making the depth of the hole 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 equal. .. Further, by making the depth of the hole portion shallower or deeper than the thickness of the substrate to be processed, the degree of plasma treatment around the substrate to be processed is intentionally made higher or lower than the inside. It is also possible to make a difference.

Further, in the tray for a plasma processing apparatus according to the present invention, since a durable portion having high plasma resistance is provided in a lower portion around each hole portion, a substrate to be processed is inserted into each hole portion to perform plasma processing. In this case, it is unlikely that the tray will be eroded by the plasma that invades from the gap between the periphery of each hole and the substrate to be processed inserted in the hole.

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

Specifically, the tray for a plasma processing apparatus according to the present invention can have the following aspects (first aspect). That is,
a) A plate-shaped upper member having one or more holes for individually accommodating each substrate to be processed and having a thickness corresponding to the thickness of the substrate to be processed.
b) Plasma having a plate-shaped member arranged under the upper member and having a lower member having a durable portion made of a material having high plasma resistance at a portion corresponding to the periphery of the hole portion on the upper surface. It can be a tray for processing equipment.

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

In the tray for the 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 the 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 into the groove.

The tray for a plasma processing apparatus according to the present invention can also have the following aspects (second aspect). That is,
a) A material with high plasma resistance that has a hole for individually accommodating each substrate to be processed, has a thickness corresponding to the thickness of the substrate to be processed, and projects from the periphery of the hole to the inside. A plate-shaped upper member with a durable edge made of
b) It can be a tray for a plasma processing device provided with a lower member which is a plate-shaped member arranged under the upper member.

As the material having high plasma resistance, yttrium (Y ₂ O ₃ ), quartz, aluminum nitride (AlN), and zirconia (ZrO ₂ ) can be used.

In the plasma processing apparatus tray according to the present invention, for example, by making the depth of the hole portion 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 made substantially equal. Can be done. Further, by making the depth of the hole portion shallower or deeper than the thickness of the substrate to be processed, the degree of plasma treatment around the substrate to be processed is intentionally made higher or lower than the inside. It is also possible to make a difference.

Further, in the tray for a plasma processing apparatus according to the present invention, since a durable portion having high plasma resistance is provided in a lower portion around each hole portion, a substrate to be processed is inserted into each hole portion to perform plasma processing. In this case, it is unlikely that the tray will be eroded by the plasma that invades from the gap between the periphery of each hole and the substrate to be processed inserted in the hole. Therefore, the tray for the plasma processing apparatus according to the present invention can be used in a state of less damage for a long period of time, and the production efficiency can be improved and the production cost can be reduced.

The schematic which shows the whole structure of a plasma processing apparatus. Top view of a tray according to an embodiment of the present invention. The central sectional view of the tray of the said embodiment. The top view (a) of the upper member, the top view (b) of the lower member, and the central sectional view (c) of the lower member constituting the tray of the embodiment. Sectional view of the tray which is the other three embodiments. A side view of a tray and an electrostatic chuck according to another embodiment. Top view of the tray according to another embodiment.

Hereinafter, the plasma processing apparatus according to the present invention will be described with reference to the accompanying drawings. The following embodiments are examples that embody the present invention and do not limit the technical scope of the present invention.

<1. Overall configuration>
Before explaining the tray 20 for the plasma processing apparatus (hereinafter, simply referred to as “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 the overall configuration of the plasma processing apparatus 10.

The plasma processing device 10 includes a vacuum container 11 and an upper electrode 12 and a lower electrode 13 provided facing the inside of the vacuum container 11. A high frequency power supply (not shown) for applying a high frequency voltage to each of the electrodes 12 and 13 is connected to the electrodes 12 and 13.

A dielectric layer 14 is provided on the upper surface of the lower electrode 13, and a tray 20 on which a substrate to be processed (hereinafter, simply referred to as a substrate) 30 is placed is placed on the upper surface of the dielectric layer 14. 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 attract the tray 20 to the electrostatic chuck portion (electrostatic adsorption device) 15. To configure. The electrostatic chuck portion 15 is of 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 unipolar type or a bipolar type, but by adopting the unipolar type, the adsorptivity of the tray 20 can be made particularly good.

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

In addition to the above-mentioned elements, the plasma processing device 10 has a gas supply unit that supplies various gases for generating plasma into the vacuum vessel 11, a vacuum exhaust device that exhausts the inside of the vacuum vessel 11 (all not shown). It is equipped with.

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

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

As shown in FIG. 3, the tray 20 in the present embodiment is formed by laminating the upper member 22 and the lower member 23. The upper member 22 and the lower member 23 may be fixed in a laminated state, or may be prepared in a separated state and used by being laminated during plasma treatment. In the latter case, it is desirable that a mechanism for positioning the upper member 22 and the lower member 23 is 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 having a predetermined number of holes 24 (4 in the example of FIG. 4) for accommodating one substrate 30. As shown in FIG. 4B, the lower member 23 is a circular flat plate having the same diameter as the upper member 22, and when the upper members 22 are stacked, the lower member 23 has a ring shape corresponding to the periphery of the hole 24. The region is a plasma resistant region 25 corresponding to the durable portion of the present invention. The plasma resistant region 25 is located from the outside of the hole 24 (indicated by the dotted line inside in FIG. 4B) when the upper member 22 is placed, and around the hole 24 when the substrate 30 is placed (FIG. 4B). Covers up to the inside of the inside (indicated by the dotted line).

In the lower member 23, the plasma resistant region 25 is formed by spraying _{a groove provided in the region with ytria (Y 2} O _{3), which is a material having high plasma resistance.} In addition, quartz, aluminum nitride (AlN), zirconia (ZrO ₂ ) and the like can be used as the material having high plasma resistance.

By setting the thickness of the upper member 22 to be the same as the thickness of the substrate 30, when the substrate 30 is placed in the substrate mounting area 21 of the tray 20, the upper surface of the tray 20 and the upper surface of the substrate 30 are flush with each other. As a result, the substrate 30 is treated more uniformly by the 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, the side surface of the lower member 23 may be provided in addition to the upper surface side. It may be configured to 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 thereof, 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 with 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 "low volume resistivity material" here 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 ・ ・. Material of cm or less). The "high volume resistivity material" here is a material having a volume resistivity ^{exceeding 1 × 10 13} Ω · cm.

The forming material (low volume resistivity material) of the lower member 23 is, for example, a ceramic (particularly, a ceramic containing a large amount of carbon is preferable), and specifically, for example, silicon carbide (SiC). As the material for forming the lower member 23, ^{a low resistivity aluminum nitride material having a volume resistivity of about 10 11} Ω · cm can also be used. "Low resistivity aluminum nitride material" means volume resistivity by dispersing conductive materials (conductive additives) such as titanium carbide and carbon fiber in ^{aluminum nitride (volume resistivity is about 10 14 Ω · cm).} Is reduced.
Further, as described above, the dielectric layer 14 of the electrostatic chuck portion 15 is made ^{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 formed of this material. It is also preferable to use the same material as the material for forming the dielectric layer 14.

The material for 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 ). As the material for forming the upper member 22, quartz, aluminum nitride (AlN), yttrium (Y ₂ O ₃ ), zirconia (ZrO ₂ ), or the like can also be used.

The lower member 23 arranged 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, so that the tray 20 is surely attracted to the electrostatic chuck portion 15. At the same time, the substrate 30 is reliably attracted to the tray 20. As a result, 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 treatment is transferred to the dielectric layer 14 through the tray 20. And is well discharged to the lower electrode 13 (outside).

Further, since the lower member 23 is covered with the upper member 22 made of a material different from this (high volume resistivity material), for example, the lower member 23 is provided with a conductive additive for resistance control or the like. Even if it is added, it will not be released by etching and contaminate the substrate 30.

In particular, here, the upper member 22 is made of a high volume resistivity material having a volume resistivity of more than ^{1 × 10 13 Ω · cm.} That is, the lower member 23 had to be made of a material having a relatively low volume resistivity so that it could be attracted to the electrostatic chuck portion 15, but the upper member 22 has no such limitation, and the constituent material thereof. A material having a relatively high volume resistivity (specifically, a high volume resistivity material having a volume resistivity of more than ^{1 × 10 13 Ω · cm) is permitted.} As a matter of course, in this high volume resistivity material, it is not necessary to add a conductive additive for resistance control, and it can be formed from a high-purity substance. Therefore, even if the upper member 22 is etched, the conductive additive that causes contamination of the substrate 30 is not released.

Further, since the upper member 22 does not have such a limitation, it is possible to use a material having a relatively high etching resistance due to plasma, such as ytria exemplified above, as a constituent material of the upper member 22. .. By adopting such a material, a tray 20 having excellent durability can be obtained.

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

<2-3. Other configuration examples>
In the above embodiment, the hole 24 of the upper member 22 is straight, but as shown in FIG. 5 (b), it projects to the inside of the hole on the lower surface side of the upper member 22. May be good. In this case, the overhanging portion 26 becomes the durable portion of the present invention. Further, similarly to the example of FIG. 5 (a), the upper member 22 may cover the periphery of the lower member 23 (FIG. 5 (c)).

When the tray 20 is formed by stacking the lower member 23 and the upper member 22 as described above (particularly, when the upper member 22 is not provided with a portion covering the side surface of the lower member 23 (FIG. 5 (b) )), the lower member It is also preferable to align the member 23 and the upper member 22 and provide an element for preventing misalignment. Specifically, for example, one of the lower member 23 and the upper member 22 may be provided with positioning pins that are erected at three or more positions on the outer peripheral edge thereof.

In the above embodiment, for example, as shown in FIG. 6, it is also preferable that the substrate mounting area 21 is provided with a cooling passage 27 formed of a groove for the cooling medium to flow through. The cooling passage 27 may extend radially from the center of the substrate mounting region 21, for example, as shown in FIG. 7 (a), or may extend radially from the center of the substrate mounting region 21, or as shown in FIG. 7 (b), the substrate mounting region 21. It may be formed along a plurality of circles arranged concentrically 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 effectively cooled.

When the tray 20 is provided with the cooling passage 27, it is also preferable to allow the cooling passage 27 to communicate with the groove 16 provided on the upper surface of the dielectric layer 14 via, for example, the communication passage 28. By doing so, the cooling medium distributed in the groove 16 can be distributed 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 the plasma processing.

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

10 ... Plasma processing device 11 ... Vacuum container 12 ... Upper electrode 13 ... Lower electrode 14 ... Dielectric layer 15 ... Electrostatic chuck portion 16 ... Groove 17 ... Cooling mechanism 20 ... Tray 21 ... Substrate mounting area 22 ... Upper member 23 ... Lower Member 24 ... Hole 25 ... Plasma resistant region 26 ... Overhanging portion 27 ... Cooling passage 28 ... Communication passage 30 ... Substrate

Claims (4)

A tray used when one or more substrates to be processed are placed on a tray and the tray is placed on an electrostatic chuck and plasma treatment is applied to the substrate to be processed.
a) A plate-shaped upper member having a hole corresponding to the thickness of the substrate to be processed and having a hole for individually accommodating each substrate to be processed.
b) A plate-shaped member arranged under the upper member, which is provided with a lower member having a durable portion made of a material having high plasma resistance in a portion corresponding to the periphery of the hole portion on the upper surface. A tray for plasma processing equipment. The tray for a plasma processing apparatus according to claim 1 , wherein the durable portion is made of a material having high plasma resistance filled in a groove formed in a lower member. The tray for a plasma processing apparatus according to claim 1 or 2 , wherein the material having high plasma resistance is ytria (Y ₂ O _3). A tray used when one or more substrates to be processed are placed on a tray and the tray is placed on an electrostatic chuck and plasma treatment is applied to the substrate to be processed.
a) A material with high plasma resistance that has a hole for individually accommodating each substrate to be processed, has a thickness corresponding to the thickness of the substrate to be processed, and projects from the periphery of the hole to the inside. A plate-shaped upper member with a durable edge made of
b) Provided with a lower member which is a plate-shaped member arranged under the upper member .
The plasma processing apparatus trays the upper material, characterized in quartz or zirconia (ZrO ₂₎ der Rukoto.

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