JP2010098010A - Etching equipment and etching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide etching equipment and an etching method capable of performing processing without any cracks of substrates during etching. <P>SOLUTION: The etching equipment includes: a clamp ring 33 that presses the periphery Sa of the substrate S and is fixed onto the substrate tray 32; and a ring member 34 provided between the clamp ring and the periphery of the substrate. In the substrate tray, a surface recess 32a is formed on a front surface, a rear recess 32b and a periphery contact surface section 32c surrounding the rear recess and abutting on a substrate electrode 31 are formed on a rear surface, and a cooling gas channel 32d is formed. A ring member is composed of a material having a heat conductivity of not more than 1.5 W/mk. By the etching equipment, the substrate tray where the substrate is placed is fitted onto the substrate electrode, the periphery of the substrate is pressed and fixed by a clamp ring, and the substrate is etched under a high-density plasma atmosphere while gas flows to the cooling gas channel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an etching apparatus and an etching method, and more particularly to an etching apparatus and an etching method for processing a substrate that can be used in an optical waveguide, an optical modulator, and the like in a plasma atmosphere.

  Conventionally, as an etching apparatus for processing pyroelectric high dielectric materials used in optical modulators, optical waveguides, etc. in plasma, a substrate electrode whose surface is coated with an anodized film, and a substrate pressing clamp made of alumina An apparatus provided with members and the like has been used, but when processing a substrate made of a pyroelectric high dielectric material, there has been a problem that substrate cracking occurs due to uneven processing temperature and charge-up. In addition to the substrate made of pyroelectric high-dielectric material, there is a through-hole substrate that has been processed to penetrate a part of the substrate on the substrate tray. No satisfactory solution has been proposed.

  For this reason, in order to eliminate temperature unevenness and charge-up, an etching apparatus has been proposed in which the shape of the substrate tray is improved and a cooling gas is allowed to flow on the front surface side and back surface side of the substrate (for example, Patent Document 1). And 2).

In addition, in order to suppress the occurrence of cracks in the pyroelectric high-dielectric substrate, the substrate mounting surface and the surface that contacts the substrate of the substrate pressing jig or clamp are made of a conductor, and the substrate surface potential and the back surface potential There has been proposed an etching apparatus provided with a substrate holding mechanism that keeps the difference small (see, for example, Patent Document 3). In this case, Ni, Cu, or Al is used as the conductor.
Japanese Patent No. 3640385 (Claims) Japanese Patent No. 3640386 (Claims) Japanese Patent Laid-Open No. 2002-373877 (Claims)

  In the former prior arts (Patent Documents 1 and 2), even if the thermal conductivity is improved to eliminate temperature unevenness and charge-up, the temperature of the clamp ring itself that fixes the substrate in the conventional substrate tray shape. Due to the rise, there is a problem that as the processing time becomes longer, the substrate itself is polarized by the pyroelectric effect and sticks to the substrate tray, making it difficult to peel off the substrate and causing substrate cracking. For example, about one substrate in five to one substrate in ten occurs.

  In the latter prior art (Patent Document 3), even if the difference between the substrate surface potential and the back surface potential is kept small, the processing time is long due to the temperature rise of the clamp ring itself that fixes the substrate. As a result, the substrate itself is polarized by the pyroelectric effect and sticks to the substrate tray, which makes it difficult to peel off the substrate and causes a problem of substrate cracking.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and by providing a specific ring member between the peripheral edge of the substrate and the clamp ring, the substrate is easily cracked during etching. It is an object of the present invention to provide an etching apparatus and an etching method that can be processed without causing any problems.

  The inventors of the present invention have considered that when a pyroelectric high-dielectric substrate is fixed by a clamp ring and plasma etching is performed, a temperature rise due to plasma irradiation is a cause of substrate cracking. As a result of examining the relationship between the temperature rise at each position and the etching time (the temperature rise against the etching time is plotted in FIG. 1 described later), the temperature of the clamp ring, particularly its tip, is easily exposed to plasma. It was noticed that a high rise was a factor of substrate cracking, and the present invention was completed.

  An etching apparatus of the present invention is an etching apparatus for processing a substrate placed on a substrate electrode in a high-density plasma atmosphere. The substrate placed in a substrate tray mounted on the substrate electrode is placed on the substrate tray. A clamp ring configured to press the peripheral edge of the substrate for fixing, and a ring member provided between the clamp ring and the peripheral edge of the substrate. A surface recess for receiving the substrate to be processed is formed, and a back surface recess and a peripheral contact surface portion surrounding the back surface recess and contacting the substrate electrode are formed on the back surface corresponding to the surface recess, and the back surface recess A plurality of cooling gas passages penetrating from the surface to the surface recess are formed, and the ring member is made of a material having a thermal conductivity of 1.5 W / mK or less. And butterflies.

  By providing a ring member made of a material having low thermal conductivity between the clamp ring and the peripheral edge portion of the substrate, an increase in the substrate temperature is suppressed, and cracking of the substrate during the etching process is reduced.

  The ring member is made of a material selected from a synthetic resin (preferably a synthetic resin selected from a thermosetting resin and a thermoplastic resin), quartz, sapphire, yttria, and silicone rubber. It is characterized by. The synthetic resin is a resin selected from a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin.

  The ring member is embedded or joined so as to protrude from at least a part of a contact surface of the clamp ring with the substrate, and the ring member is configured to press the peripheral portion of the substrate by the clamp ring. It is characterized by that.

  The etching method of the present invention is an etching method for processing a substrate placed on a substrate electrode by introducing a gas into a vacuum chamber to form high-density plasma using microwaves or high-frequency waves. The substrate tray thus mounted is mounted on the substrate electrode, and the peripheral edge of the substrate is pressed with a clamp ring via a ring member made of a material having a thermal conductivity of 1.5 W / mK or less, and the substrate is substrate The substrate is fixed on the tray, and the substrate is processed while flowing the cooling gas through the cooling gas flow path. As the substrate tray, a surface recess for receiving the substrate to be processed is formed on the surface, and corresponds to the surface recess. A back surface concave portion and a peripheral contact surface portion that surrounds the back surface concave portion and contacts the substrate electrode are formed in the back surface portion, and a plurality of cooling gas flow paths that penetrate from the back surface concave portion to the front surface concave portion are formed Characterized by processing the substrate using a substrate tray.

  In the etching method, the ring member is made of a material selected from a synthetic resin (preferably a synthetic resin selected from a thermosetting resin and a thermoplastic resin), quartz, sapphire, yttria, and silicone rubber. It is preferable to use one. This synthetic resin is preferably a resin selected from a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin.

  In the etching method, the ring member is embedded or bonded so as to protrude at least part of a contact surface of the clamp ring with the substrate, and the ring member presses the peripheral edge of the substrate. Etching may be performed using the above-mentioned ones.

  In the etching method, etching is performed by fixing the substrate with a clamping force that does not give a substantial mechanical stress to the substrate and can release the stress generated during the processing of the substrate.

  According to the etching method of the present invention, by providing a ring member made of a material having low thermal conductivity between the clamp ring and the peripheral portion of the substrate, substrate cracking during the etching process is reduced.

  According to the present invention, when etching a fragile substrate, the substrate can be kept at a uniform low temperature during processing, and charge-up can be suppressed, so that processing can be performed without causing substrate cracking. There is an effect that can be done.

  Hereinafter, in the embodiment of the present invention, a pyroelectric high-dielectric substrate is described as an example of the substrate, but the present invention is applicable to a substrate that is easily broken during etching.

  First, the inventors examined the influence of temperature on each position of the clamp ring by the plasma and the substrate when the Si substrate was fixed by the clamp ring and high-frequency plasma etching was performed. The result is shown in FIG. As shown in the upper part of the graph of FIG. 1, etching was performed with the clamp ring in contact with the substrate and fixed, and the temperature at each position A, B, C, D, E was measured.

  As is clear from FIG. 1, when the substrate is held by the mechanical clamp, the temperature at the tip (position A) and the center of the clamp ring (position B), which are high-frequency application areas of the clamp ring, is independent of the etching time. It was found that the outer peripheral edge of the clamp ring (position C) and the back metal part supporting the clamp ring (position D) were higher. Since the clamp ring was cracked at an etching time of about 1400 seconds and the tip temperature of the clamp ring was about 350 ° C., it was considered that the temperature rise at the tip (position A) might be a cause of substrate cracking. The temperature of the Si substrate measured at the position E rose at the beginning of etching, but became constant after about 200 seconds.

  A pyroelectric high-dielectric substrate used in this embodiment, for example, a substrate made of lithium niobate (LN) has a high temperature of 100 ° C. to 150 ° C., 200 ° C., and 300 ° C. as shown in FIG. It is known that the generation of pyroelectric effect (voltage generation) increases with time. When the pyroelectric effect is generated, the substrate is charged and the substrate is charged up, and it becomes easy to catch on the tray.

  Therefore, as the processing time becomes longer due to the rise in temperature of the clamp ring for fixing the substrate, particularly the tip thereof, the substrate itself is polarized by the pyroelectric effect and sticks to the substrate tray, making it difficult to peel off the substrate. At the same time, it is considered that the substrate is cracked. Therefore, in order to eliminate the crack of the substrate, it is necessary to take measures so that the temperature of the clamp ring, particularly the substrate contact portion which is the tip portion thereof, does not increase.

  According to an embodiment of an etching apparatus according to the present invention, a substrate mounted on a substrate electrode in an etching apparatus for processing a pyroelectric high-dielectric substrate placed on a substrate electrode in a high-density plasma atmosphere. A clamp ring configured to press the peripheral edge of the substrate to fix the substrate placed in the tray on the substrate tray, and a ring member provided between the clamp ring and the peripheral edge of the substrate The substrate tray is formed with a surface recess for receiving the substrate to be processed on the surface, and in contact with the substrate electrode surrounding the back recess and the back recess corresponding to the surface recess. And a plurality of cooling gas passages penetrating from the back surface concave portion to the front surface concave portion, and the ring member has a thermal conductivity of 1.5 W / mK or less. Have It is preferably those composed of a material.

  As described above, by providing the ring member having low thermal conductivity between the clamp ring and the peripheral edge portion of the substrate, the substrate cracking during the etching process is extremely reduced. In this case, in addition to the pyroelectric high-dielectric substrate, the same etching apparatus as described above is used for a through-hole substrate that has been processed to penetrate part of the substrate on the substrate tray as a substrate that is likely to crack. For example, substrate cracking during the etching process is reduced.

  The ring member is preferably composed of a material selected from synthetic resin, quartz, sapphire, yttria, and silicone rubber, and the synthetic resin is selected from a thermosetting resin and a thermoplastic resin. Preferably, the synthetic resin is a resin selected from a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin, and the ring member is at least a contact surface of the clamp ring with the substrate. It is preferable that the ring member is embedded or joined so as to protrude partially, and the ring member is configured to press the peripheral edge of the substrate by a clamp ring.

  According to the embodiment of the etching method of the present invention, a pyroelectric high dielectric material is formed on a substrate electrode by introducing a gas into a vacuum chamber to form a high-density plasma using microwaves or high-frequency waves. In an etching method for processing a body substrate, a substrate tray on which a substrate is placed is mounted on a substrate electrode, and a peripheral portion of the substrate is made of a material having a thermal conductivity of 1.5 W / mK or less And fixing the substrate on the substrate tray by pressing with a clamp ring, and processing the substrate while flowing the cooling gas through the cooling gas flow path, and receiving the substrate to be processed on the surface as the substrate tray A front surface concave portion is formed, and a rear surface concave portion and a peripheral contact surface portion that surrounds the rear surface concave portion and contacts the substrate electrode are formed on the back surface portion corresponding to the front surface concave portion, and from the rear surface concave portion to the front surface concave portion It is preferred to process the substrate using a substrate tray which a plurality of cooling gas flow path is formed for passing.

  The material of the ring member, the type of synthetic resin, the configuration of the ring member, etc. in this etching method are the same as those described in the etching apparatus. Further, in this etching method, it is preferable to fix the substrate with a clamping force that does not give a substantial mechanical stress to the substrate and can release the stress generated during the processing of the substrate.

  According to another embodiment of an etching apparatus according to the present invention, in an etching apparatus for processing a pyroelectric high dielectric substrate placed on a substrate electrode in a high-density plasma atmosphere, the etching apparatus is mounted on the substrate electrode. A clamp ring configured to press a peripheral edge of the substrate to fix the substrate placed in the substrate tray on the substrate tray, and provided between the clamp ring and the peripheral edge of the substrate. A ring member made of a material having a thermal conductivity of 1.5 W / mK or less, preferably 0.5 W / mK or less, and a surface on which the substrate tray receives a substrate to be processed. A concave portion is formed, and a back surface concave portion and a peripheral contact surface portion that surrounds the back surface concave portion and contacts the substrate electrode are formed on the back surface portion corresponding to the front surface concave portion, and a plurality of holes penetrating from the back surface concave portion to the front surface concave portion The ring member is made of aluminum in which a reject gas passage is formed, and the ring member is selected from a thermosetting resin and a thermoplastic resin, for example, a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin. In addition, the ring member may be a separate member from the clamp ring, or the clamp ring may be in contact with the substrate, or a material selected from quartz, sapphire, yttria, and silicone rubber. It may be embedded or joined so as to protrude from at least a part of the surface. Silicone rubber is useful when it is not desired to damage the outer peripheral edge of the substrate.

  As described above, by providing the ring member having low thermal conductivity between the clamp ring and the peripheral edge portion of the substrate, the substrate cracking during the etching process is extremely reduced. For example, one sheet can be divided by 500 sheets.

  According to another embodiment of the etching method according to the present invention, a pyroelectric property placed on a substrate electrode is formed by introducing a gas into a vacuum chamber to form a high-density plasma using microwaves or high-frequency waves. In an etching method for processing a high dielectric substrate, a substrate tray on which a substrate is placed is mounted on a substrate electrode, and the peripheral portion of the substrate is a synthetic resin (preferably a thermosetting resin or a thermoplastic resin, For example, a resin selected from polyimide resin, epoxy resin, fluorine resin, and phenol resin), 1.5 W / mK or less, preferably 0.5 W / mK or less selected from quartz, sapphire, yttria, and silicone rubber. A clamp ring is used to provide a substantial mechanical stress to the substrate through a ring member made of a material having a thermal conductivity, and is generated during processing of the substrate. The substrate is to be processed on the surface as a substrate tray by pressing the substrate with a clamping force that can escape the substrate and fixing the substrate on the substrate tray, and processing the substrate while flowing the cooling gas through the cooling gas flow path. A surface recess is formed, and a back surface recess and a peripheral contact surface portion that surrounds the back surface recess and contacts the substrate electrode are formed on the back surface corresponding to the inside of the surface recess, and from the back surface recess to the surface recess A substrate is processed using a substrate tray in which a plurality of cooling gas flow paths are formed.

  Examples of the fluororesin include PTFE such as Teflon (registered trademark), PFA, FEP, ETFE, PVDF, ECTFE, PCTFE, and PVF. The ring member is preferably made of a material selected from a polyimide resin and an epoxy resin.

  The thermal conductivity of the material constituting the ring member is usually as shown in Table 1 below.

  As described above, the ring member needs to be made of a material having a low thermal conductivity of 1.5 W / mK or less. In addition to this thermal conductivity, these materials are used to press the clamp ring. It is not destroyed against pressure (clamping force) and has sufficient strength to withstand pressing force, for example, compressive strength of about 12 MPa or more, and the atmospheric temperature during etching is usually 100 ° C. Therefore, it is desirable to have heat resistance equal to or higher than this temperature.

  Examples of the substrate that can be used in the present invention include a substrate made of a pyroelectric high-dielectric material, and a through-substrate that has been processed to penetrate a part of the substrate on a substrate tray. In this case, the pyroelectric high dielectric substrate is not particularly limited, and is selected from, for example, lithium niobate (LN), lithium tantalate (LT), PZT, and magnesium oxide, scandium oxide, and titanium oxide. Examples thereof include lithium niobate and lithium tantalate doped with at least one of them, and a substrate made of quartz.

  FIG. 3 shows a main part of an etching apparatus according to an embodiment of the present invention used when etching a pyroelectric high dielectric substrate.

  In FIG. 3, the substrate electrode 31 is made of aluminum and is disposed in a vacuum chamber (not shown), and a substrate tray 32 on which the substrate S is placed is mounted on the substrate electrode 31. In order to fix the substrate S placed in the substrate tray 32 on the substrate tray 32, a clamp ring 33 configured to press the peripheral edge of the substrate S is provided. A ring member 34 made of a material having a predetermined thermal conductivity is provided between the peripheral edge portion. The lower surface 34 a of the inner peripheral edge of the ring member 34 is configured to overlap the peripheral edge Sa of the substrate S on which a resist pattern may be provided, and the lower surface 34 a is in contact with the ring member 34 that contacts the substrate tray 32. It is demarcated by the surface part 34b, and it is comprised so that a level | step difference may be made between the lower surface 34a and the contact surface part 34b. The clamp ring 33 is configured to be movable in the vertical direction perpendicular to the substrate, and the shape thereof is not particularly limited as long as it can hold the substrate.

  In the above-described substrate tray 32, a surface recess 32a for receiving the substrate S made of pyroelectric high dielectric is formed on the surface. The surface recess 32a is formed in accordance with the shape and outer dimensions of the substrate S, and the surface thereof has a high flatness and a high smoothness so that a contact area with the substrate S as an insulator is as wide as possible. It can be done. A back surface recess 32b is formed on the back surface of the substrate tray 32 at a portion corresponding to the front surface recess 32a. The back surface recess 32b is defined by a peripheral contact surface portion 32c that contacts the substrate electrode 31, and the bottom surface of the back surface recess 32b. And a peripheral contact surface portion 32c. The peripheral contact surface portion 32c is formed to have high flatness and high surface accuracy. There are no particular restrictions on the shape and outer size of the back surface recess 32b, as long as the object of the present invention can be achieved, and the outer size may be larger or smaller than the outer size of the front surface recess 32a. .

  Furthermore, a plurality of cooling gas flow paths for flowing cooling gas introduced into the substrate tray 32 through the cooling gas passage 31 a penetrating the substrate electrode 31 from the back surface recess 32 b of the substrate tray 32 to the front surface recess 32 a. 32d is provided through. The level difference between the bottom surface of the back surface recess 32b of the substrate tray 32 and the surrounding contact surface portion 32c is set to a height such as 50 μm or more so as to obtain a good cooling efficiency by a cooling gas that is an inert gas such as He. The upper limit is about 1 mm due to the current apparatus configuration.

  A cooling gas supply source 36 is connected to an inlet of the cooling gas passage 31 a provided in the substrate electrode 31 via a mass flow meter 35 disposed outside the vacuum chamber. The cooling gas can be supplied to the back surface and the front surface of the substrate tray 32 via 35 and the passage 31a.

  A guide ring 37 for positioning the substrate tray 32 is provided on the substrate electrode 31, and the substrate S placed on the substrate tray 32 positioned by the guide ring 37 is connected to the clamp ring 33. Thus, the ring member 34 is supported and fixed at, for example, three points. In this case, the pressing force on the substrate S should be appropriately set to a force that does not give an excessive mechanical stress to the substrate and can release the stress generated during the processing of the substrate. The clamp ring 33 is preferably made of a metal oxide that is a high dielectric material such as alumina. For example, alumina having a low etching rate in plasma and strong etching resistance is most preferable.

  In the etching apparatus described above, a step is provided between the bottom surface of the back surface concave portion 32b of the substrate tray 32 and the peripheral contact surface portion 32c. Instead of providing a step in the peripheral portion on the back surface side of the substrate tray 32, a predetermined thickness is provided. A ring-shaped cushioning material may be provided.

  Next, the operation of the etching apparatus shown in FIG. 3 configured as described above will be described.

When etching using this etching apparatus, gas is introduced into a vacuum chamber and high-density plasma is formed using microwaves or high-frequency waves. As an etching gas, a gas used for etching a pyroelectric high dielectric substrate, for example, a fluorine-based gas (for example, CF ₄ , C ₄ F ₈ , SF _6, etc.) can be used.

  A substrate tray 32 on which a pyroelectric high-dielectric substrate S carried from a loading chamber (not shown) is placed is loaded onto the substrate electrode 31, positioned by a guide ring 37, and positioned on the back side of the substrate tray 32. The peripheral contact surface portion 32 c is attached in close contact with the surface of the substrate electrode 31. Next, the peripheral edge of the substrate S placed on the surface recess 32 a of the substrate tray 32 is pressed through the ring member 34 using the clamp ring 33, and no substantial mechanical stress is applied to the substrate S. In addition, the substrate S is fixed on the substrate tray 32 with a pressing force capable of releasing the stress generated during the processing of the substrate S.

  Thereafter, the cooling gas is introduced from the cooling gas supply source 36 to the rear surface of the substrate tray 32 through the mass flow meter 35 and the passage 31a up to 1730 Pa, and the cooling gas is caused to flow through the cooling gas flow path 32d. S is set to a desired cooling temperature, and the substrate S is etched while flowing this cooling gas. As a result, temperature rises at the tip of the clamp ring and the substrate were suppressed (substrate temperature was approximately 120 ° C. or less), and substrate cracking could be reduced.

  In this case, the cooling gas introduced through the passage 31a flows (leaks) mainly along the back side of the substrate tray 32, that is, between the substrate electrode 31 and the substrate tray 32, and the surface side of the substrate tray 32, that is, It may be configured to stay between the surface of the substrate tray 32 and the substrate S but not substantially flow (do not leak), or the cooling gas introduced through the passage 31a is mainly used as the substrate tray 32. Flow (leak) between the front surface side of the substrate tray 32 and the surface of the substrate tray 32 and the substrate S, and stay on the back surface side of the substrate tray 32, that is, between the substrate electrode 31 and the substrate tray 32. May not flow (does not leak).

  The ring member 34 in the etching apparatus shown in FIG. 3 is provided between the clamp ring 33 and the substrate S as a separate member from the clamp ring 33. However, as shown in FIG. The ring 43 is embedded in a part of the contact surface with the substrate S so as to protrude, and the peripheral portion of the substrate S is pressed by the protruding portion 44a which is the contact surface of the embedded ring member 44 with the substrate S. Even if configured, the same effect as in the case of the etching apparatus shown in FIG. 3 can be obtained. In FIG. 4, 41 is a substrate electrode, 41a is a cooling gas passage, 42 is a substrate tray, 42a is a concave portion on the front surface, 42b is a concave portion on the back surface, 42c is a peripheral contact surface portion, 42d is a cooling gas flow path, 45 is a mass flow meter, 46 Indicates a cooling gas supply source, and 47 indicates a guide ring.

  In the above-described embodiment, the case where a substrate made of a pyroelectric high dielectric material is mainly used has been described. However, the substrate is not limited to this, and may be any substrate as long as substrate cracking is likely to occur during processing. Alternatively, a through-substrate or the like that has been processed to penetrate a part of the substrate on the tray may be used.

  According to the etching apparatus and the etching method of the present invention, it is possible to reduce substrate cracking when etching a fragile substrate, so that it is effective in the field of semiconductor devices including technical fields such as optical waveguides and optical modulators. Available.

The graph which shows the influence of the temperature with respect to each position of the clamp ring by a plasma, and a board | substrate at the time of fixing and etching a Si substrate with a clamp ring. The graph which shows the relationship between the temperature and the pyroelectric effect (voltage generation) in the board | substrate which consists of lithium niobate (LN). The block diagram which shows typically the example of 1 structure of the principal part of the etching apparatus of this invention. The block diagram which shows another example of a structure of the principal part of the etching apparatus of this invention typically.

Explanation of symbols

31 Substrate electrode 31a Cooling gas passage 32 Substrate tray 32a Front recess 32b Back recess 32c Peripheral contact surface portion 32d Cooling gas flow path 33 Clamp ring 34 Ring member 34a Lower surface 34b Contact surface portion 35 Mass flow meter 36 Cooling gas supply source 37 Guide ring
41 Substrate electrode 41a Cooling gas passage 42 Substrate tray 42a Front surface concave portion 42b Back surface concave portion 42c Peripheral contact surface portion 42d Cooling gas flow path 43 Clamp ring 44 Ring member 44a Protruding portion 45 Mass flow meter 46 Cooling gas supply source 47 Guide ring S Substrate Sa Substrate Peripheral part A, B, C, D, E position

Claims (11)

In an etching apparatus for processing a substrate placed on a substrate electrode in a high-density plasma atmosphere, the periphery of the substrate is used to fix the substrate placed in the substrate tray mounted on the substrate electrode on the substrate tray. And a ring member provided between the clamp ring and the peripheral edge of the substrate, and the substrate tray receives the substrate to be processed on the surface. A front surface concave portion is formed, and a rear surface concave portion and a peripheral contact surface portion that surrounds the rear surface concave portion and contacts the substrate electrode are formed on the back surface portion corresponding to the front surface concave portion, and penetrates from the rear surface concave portion to the front surface concave portion. An etching apparatus, wherein a plurality of cooling gas flow paths are formed, and the ring member is made of a material having a thermal conductivity of 1.5 W / mK or less. 2. The etching apparatus according to claim 1, wherein the ring member is made of a material selected from synthetic resin, quartz, sapphire, yttria, and silicone rubber. The etching apparatus according to claim 2, wherein the synthetic resin is a resin selected from a thermosetting resin and a thermoplastic resin. The etching apparatus according to claim 2, wherein the synthetic resin is a resin selected from a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin. The ring member is embedded or joined so as to protrude from at least a part of a contact surface of the clamp ring with the substrate, and the ring member is configured to press the peripheral portion of the substrate by the clamp ring. The etching apparatus of any one of Claims 1-4 characterized by the above-mentioned. In an etching method for processing a substrate placed on a substrate electrode by introducing a gas into a vacuum chamber to form a high-density plasma using microwaves or high-frequency waves, the substrate tray on which the substrate is placed is placed on the substrate electrode. The substrate is mounted on the substrate, and the periphery of the substrate is pressed by a clamp ring through a ring member made of a material having a thermal conductivity of 1.5 W / mK or less to fix the substrate on the substrate tray, and then cooled. The substrate tray is formed with a surface recess for receiving the substrate to be processed on the surface, and a back surface recess is formed on the back surface corresponding to the surface recess. A substrate contact is formed using a substrate tray in which a peripheral contact surface portion surrounding the back surface recess and contacting the substrate electrode is formed, and a plurality of cooling gas passages penetrating from the back surface recess to the front surface recess are formed. Etching method characterized by Engineering. The etching method according to claim 6, wherein the ring member is made of a material selected from synthetic resin, quartz, sapphire, yttria, and silicone rubber. The etching method according to claim 7, wherein the synthetic resin is a resin selected from a thermosetting resin and a thermoplastic resin. The etching method according to claim 7, wherein the synthetic resin is a resin selected from a polyimide resin, an epoxy resin, a fluororesin, and a phenol resin. The ring member is embedded or joined so as to protrude at least part of the contact surface of the clamp ring with the substrate, and the ring member is configured to press the peripheral edge of the substrate. The etching method according to any one of claims 6 to 9. The said board | substrate is fixed by the clamping force of the grade which does not give a substantial mechanical stress to a board | substrate and can release the stress which generate | occur | produces during a process of a board | substrate. 2. The etching method according to item 1.

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