Electrostatic chuck device

Disclosed is an electrostatic chuck device for increasing electrostatic adsorptive force for a focus ring and uniformly cooling the focus ring. In such a device, a mounting table has a holder in the periphery of a placing surface along the circumferential direction of a focus ring, the holder has a pair of banks in the circumferential direction, and an annular groove formed between these banks, and in at least a bank on an outer circumferential position of the focus ring among the pair of the banks, a micro-protruding part including a plurality of micro-protrusions is on a surface facing the focus ring, or convex parts are on a bottom of the groove. The convex parts do not contact the focus ring, and the pair of banks or plurality of micro-protrusions contacts the focus ring and electrostatically adsorbs the focus ring in coordination with the convex parts.

The present application is a National Stage Application under 35 U.S.C. § 371of International Application No. PCT/JP2015/076890 filed Sep. 24, 2015, which claims the benefit of priority to Japanese Patent Application No. 2014-201302 filed Sep. 30, 2014 and Japanese Patent Application No. 2014-201303 filed Sep. 30, 2014, the disclosures of all of which are hereby incorporated by reference in their entireties. The International Application was published in Japanese on Apr. 7, 2016 as WO 2016/052291.

TECHNICAL FIELD

The present invention relates to an electrostatic chuck device and, in more detail, to an electrostatic chuck device that is preferably used in vacuum process devices such as etching devices, sputtering devices, and CVD devices which are applied to the manufacturing processes of semiconductor devices, liquid crystal display devices, and the like.

BACKGROUND ART

Recently, in the manufacturing processes of semiconductors, in response to enhancement of the integration or performance of elements, there has been a demand for additional improvements in fine processing techniques. Among these manufacturing processes of semiconductors, etching techniques are one type of important fine processing techniques. Recently, among etching techniques, plasma etching techniques have been mainstreamed due to their capability of highly efficient fine processes of large areas.

Plasma etching techniques are one type of dry etching techniques. Plasma etching techniques are techniques in which fine patterns are formed in solid materials in the following fashion.

A mask pattern is formed on a solid material which is a process subject using a resist. Next, in a state in which the solid material is supported in a vacuum, a reactive gas is introduced into the vacuum, and a high-frequency electric field is applied to the reactive gas. Then, accelerated electrons collide with gas molecules and thus fall into a plasma state, and radicals (free radicals) generated from this plasma and ions react with the solid material, thereby producing a reaction product. In addition, this reaction product is removed, thereby forming a fine pattern on the solid material.

Meanwhile, as thin film-growing techniques in which raw material gas is chemically combined together through the action of plasma and the obtained compound is deposited on a substrate, there is, for example, a plasma CVD method. The plasma CVD method is a film-forming method in which plasma discharge is caused by applying a high-frequency electric field to gas including raw material molecules, the raw material molecules are decomposed using electrons accelerated by the plasma discharge, and the obtained compound is deposited. Reactions that are not caused by thermal excitation alone at a low temperature become possible in plasma since gas in the system collides with each other and is activated, thereby forming radicals.

In semiconductor-manufacturing devices in which plasma is used such as plasma etching devices and plasma CVD devices, in the related art, an electrostatic chuck device in which wafers can be easily mounted and fixed on a specimen table and be maintained at a desired temperature is used. This electrostatic chuck device includes, in the upper part, a ring member (focus ring) which surrounds the wafer-placing surface and is disposed at the outer circumferential edge of a wafer adsorption part.

However, in plasma etching devices of the related art, when plasma is radiated to a wafer fixed to the electrostatic chuck device, the surface temperature of the wafer increases. Therefore, in order to prevent the increase in the surface temperature of wafers, a cooling medium such as water is circulated in a base part for adjusting the temperature of the electrostatic chuck device so as to cool the wafer from the lower side.

For electrostatic chuck devices, techniques in which the uniformity of the temperature at the outer circumference of wafers is improved by providing second electrostatic adsorption means for adsorbing the focus ring to the outer circumference of the wafer are known (for example, refer to Patent Literature No. 1). In these techniques, second electrostatic adsorption means is provided, whereby the focus ring is adsorbed to an electrostatic chuck part with a force greater than the force that adsorbs wafers, and a cooling medium (cooling gas) is blown to the rear surface of the focus ring, thereby adjusting the temperature of the focus ring and making the surface temperature of the wafers uniform.

In addition, techniques in which gas-providing parts are provided to the wafer adsorption part adsorbed using the electrostatic chuck part and the focus ring and the temperatures of the wafer adsorption part and the focus ring are respectively and independently controlled, whereby the uniformity of the surface temperature of wafers are improved are known (for example, refer to Patent Literature No. 2). In these techniques, a protruding part is formed on the contact surface of the electrostatic chuck part which is in contact with the focus ring or the surface roughness of the contact surface is increased along the circumferential direction of the electrostatic chuck part, whereby the heat-transferring area in the electrostatic chuck part, which is formed by cooling gas, is increased and cooling gas is communicated between the electrostatic chuck part and the focus ring. In addition, in these techniques, a groove is formed on a part of the electrostatic chuck part which is in contact with the focus ring, whereby the diffusivity of cooling gas in the focus ring is improved.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, when only the force for adsorbing the focus ring is increased as in the techniques described in Patent Literature No. 1, there has been a problem in that it is not possible to reliably control the surface temperature of wafers.

In addition, in the techniques described in Patent Literature No. 2, since the contact area between the protruding part formed in the electrostatic chuck part and the focus ring is small, there has been a problem in that the force for adsorbing the focus ring to the electrostatic chuck part is insufficient and the focus ring cannot be sufficiently cooled. In addition, when the surface roughness of the contact surface of the electrostatic chuck part is increased along the circumferential direction of the electrostatic chuck part, it is not possible to obtain the sufficient flow of cooling gas in the thickness direction of the focus ring, and thus there has been a problem in that it is not possible to uniformly cool wafers (the focus ring). Furthermore, in a case in which a groove is formed in the electrostatic chuck part, a temperature difference is caused between the groove and other parts, and thus there has been a problem in that it is not possible to uniformly cool wafers (the focus ring).

The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide an electrostatic chuck device capable of increasing the force for electrostatically adsorbing a focus ring and uniformly cooling the focus ring.

Solution to Problem

As a result of intensive studies for solving the above-described problems, the present inventors found that, when a holder for electrostatically adsorbing a focus ring is provided along the circumferential direction of the focus ring and has a pair of banks for placing the focus ring thereon and an annular groove formed between these banks, convex parts are provided on the bottom of the groove, a micro-protruding part comprising a plurality of micro-protrusions is formed on a surface facing the focus ring in at least a bank on an outer circumferential position of the focus ring among the pair of the banks, furthermore, a cooler provides a heat-transferring gas to the groove, and the pair of the banks is in contact with the focus ring in coordination with the convex parts which are not in contact with the focus ring or the plurality of the micro-protrusions is in contact with the focus ring, thereby electrostatically adsorbing the focus ring, it is possible to increase the force for electrostatically adsorbing the focus ring using the holder and uniformly cool the focus ring, and completed the present invention.

An electrostatic chuck device of the present invention comprises a mounting table provided with a placing surface on which a plate-like specimen is to be placed; an annular focus ring being placed on the mounting table and surrounding a periphery of the placing surface; and a cooler for cooling the mounting table and the focus ring, the mounting table comprises a holder for electrostatically adsorbing the focus ring, the holder being provided in a periphery of the placing surface along a circumferential direction of the focus ring, the holder comprises a pair of banks being provided in a circumferential direction and being for placing the focus ring thereon, and an annular groove formed between the pair of the banks, the cooler provides a heat-transferring gas to the groove, convex parts are provided on a bottom of the groove, the pair of the banks is in contact with the focus ring, the convex parts are not in contact with the focus ring, and the pair of the banks and the convex parts electrostatically adsorb the focus ring in a coordinating fashion.

Alternatively, the electrostatic chuck device of the present invention comprises a mounting table provided with a placing surface on which a plate-like specimen is to be placed; an annular focus ring being placed on the mounting table and surrounding a periphery of the placing surface; and a cooler for cooling the mounting table and the focus ring, the mounting table comprises a holder for electrostatically adsorbing the focus ring, the holder being provided in a periphery of the placing surface along a circumferential direction of the focus ring, the holder comprises a pair of banks being provided in a circumferential direction and being for placing the focus ring thereon, and an annular groove formed between the pair of the banks, a micro-protruding part comprising a plurality of micro-protrusions is formed on a surface facing the focus ring in at least a bank on an outer circumferential position of the focus ring among the pair of the banks, the cooler provides a heat-transferring gas to the groove, and the plurality of the micro-protrusions is in contact with the focus ring and electrostatically adsorbs the focus ring.

Advantageous Effects of Invention

According to the present invention, it is possible to provide an electrostatic chuck device capable of increasing the force for electrostatically adsorbing a focus ring and uniformly cooling the focus ring.

DESCRIPTION OF EMBODIMENTS

Embodiments of an electrostatic chuck device of the present invention will be described.

Meanwhile, the present embodiments are simply specific description for better understanding of the gist of the invention and does not limit the present invention unless particularly otherwise described.

FIG. 1is a schematic cross-sectional view illustrating an embodiment of an electrostatic chuck device of the present invention, andFIG. 2is a schematic cross-sectional view illustrating an embodiment of the electrostatic chuck device of the present invention and is a partial enlarged view illustrating a region indicated by α inFIG. 1in an enlarged fashion.

An electrostatic chuck device10of the present embodiment is schematically constituted of a mounting table11provided with a placing surface (a placing surface (upper surface)24aof a dielectric layer24described below) on which a plate-like specimen W is to be placed, an annular focus ring12being placed on the mounting table11and surrounding the periphery of the placing surface (the placing surface24a), and a cooler13for cooling the mounting table11and the focus ring12.

The mounting table11has a mounting table main body11A, a disc-like electrostatic chuck part14being provided on the mounting table main body11A and having the placing surface (the placing surface24a), and a holder15being provided in the periphery of the placing surface (the placing surface24a) along the circumferential direction of the focus ring12and being for electrostatically adsorbing the focus ring12.

The holder15has a pair of banks16(16A and16B) being provided in the circumferential direction of the focus ring12and being for placing the focus ring12thereon, and an annular groove17formed between the pair of the banks16. On a bottom17aof the groove17, convex parts18are provided, the convex parts protruding toward a surface for placing the focus ring12(in the thickness direction of the holder15) in the bank16.

In the pair of the banks16, on a surface16afacing the focus ring12, a micro-protruding part16cincluding a plurality of micro-protrusions16b,16b, . . . may be formed.

When the focus ring12is placed on the holder15, as illustrated inFIG. 1, the pair of the banks16(16A and16B) or the micro-protrusions16b,16b, . . . formed on the surfaces16afacing the focus ring12in the pair of the banks (16A and16B) come into contact with the focus ring12, and the convex parts18do not come into contact with the focus ring12. That is, there is a space (void) between a lower surface12aof the focus ring12and a peak (upper surface)18aof the convex part18or the surface16afacing the focus ring12in the bank16. In addition, there is also a space (void) between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18, and the size of the space, that is, the distance between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18is not particularly limited, but is set so that an electrostatic adsorptive force acts between the focus ring12and the convex parts18. In a case in which the micro-protrusions16b,16b, . . . are provided on the surfaces16afacing the focus ring in the banks16(16A and16B), only the micro-protrusions16b,16b, . . . in the banks16come into contact with the lower surface12aof the focus ring12, and thus the banks16electrostatically adsorb the focus ring12while the lower surface12aof the focus ring12is not contact with the surfaces16afacing the focus ring12in the banks16.

The size of the space (void) between the lower surface12aof the focus ring12and the surface16afacing the focus ring12in the bank16, that is, the height of the micro-protrusions16b,16b, . . . from the surface16afacing the focus ring12in the bank16is not particularly limited, but is set so that a heat-transferring gas provided into the groove17by the cooler13can be communicated.

In addition, the size of the space (void) between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18, that is, the distance between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18is not particularly limited, but is set so that an electrostatic adsorptive force acts between the focus ring12and the convex parts18.

In the pair of the banks16, the amount of the heat-transferring gas flowing out of the bank16A on the outer circumferential position of the focus ring12is larger than the amount of the heat-transferring gas flowing out of the other bank16B.

Examples of a specific constitution for providing a difference in the amounts of the heat-transferring gas flowing out of the pair of the banks16as described above include two constitutions described below.

The distance between the plurality of the micro-protrusions16b,16b, . . . provided on the bank16A on the outer circumference of the focus ring12is set to be larger than the distance between the plurality of micro-protrusions16b,16b, . . . provided on the bank16B on the inner circumference of the focus ring12. When the above-described constitution is provided, a larger amount of the heat-transferring gas provided into the groove17by the cooler13flows outside from the bank16A in which the distance of the micro-protrusions16b,16b, . . . is larger. Therefore, it is possible to uniformly cool the focus ring12.

Meanwhile, in the bank16A, the distance between the micro-protrusions16b,16b, . . . is not particularly limited, but is set so that a larger amount of the heat-transferring gas flows outside from the bank16A rather than from the bank16B.

In addition, the height of the micro-protrusions16b,16b, . . . provided on the bank16A on the outer circumference of the focus ring12is larger than that of the micro-protrusions16b,16b, . . . provided on the bank16B on the inner circumference of the focus ring12. When the above-described constitution is provided, a larger amount of the heat-transferring gas provided into the groove17by the cooler13flows outside from the bank16A in which the height of the micro-protrusions16b,16b, . . . is larger. Therefore, it is possible to uniformly cool the focus ring12.

Meanwhile, in the bank16A, the height of the micro-protrusions16b,16b, . . . is not particularly limited, but is set so that a larger amount of the heat-transferring gas flows outside from the bank16A rather than from the bank16B.

The convex part18is constituted of, for example, a plurality of columnar protruded parts18A,18B, . . . . The protruded parts18A,18B, . . . are provided away from each other. In a case in which the electrostatic chuck device10(the holder15) is seen in a planar view, the protruded parts18A,18B, . . . are provided throughout the entire region of the groove17. The intervals between the protruded parts18A,18B, . . . are not particularly limited.

In addition, the convex part18may be constituted of, for example, a plurality of protruded strips18A,18B, . . . . The protruded strips18A,18B, . . . are provided away from each other. In a case in which the electrostatic chuck device10(the holder15) is seen in a planar view, the protruded strips18A,18B, . . . may have an annular shape so that the protruded strips continue with each other along the annular groove17or may have a discontinuous arc shape so that the protruded strips are provided at intervals. In a case in which the protruded strips18A,18B, . . . have an annular shape so that the protruded strips continue with each other along the annular groove17, the protruded strips18A,18B, . . . are provided concentrically with the groove17. The intervals between the protruded strips18A,18B, . . . are not particularly limited.

When the convex part18is constituted of the plurality of the protruded parts18A,18B, . . . , the area of the convex parts18(the combined area of all of the protruded parts18A,18B, . . . ) is preferably 10% or more and 80% or less and more preferably 20% or more and 50% or less of the area of the groove17(the area of the bottom17aof the groove17) in a case in which the electrostatic chuck device10(the holder15) is seen in a planar view.

When the area of the convex parts18is less than 10% of the area of the groove17, the electrostatic adsorptive force acting between the protruded parts18A,18B, . . . and the focus ring12, that is, the force that attracts the focus ring12to the protruded parts18A,18B, . . . excessively weakens, and thus it is not possible to fix the focus ring12to the holder15. On the other hand, when the area of the convex parts18exceeds 80% of the area of the groove17, the space between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18becomes too small, and thus the amount of heat-transferring gas flowing through the space becomes small. As a result, the effect of cooling the focus ring12using heat-transferring gas becomes weak, and a difference is caused between the surface temperature of the focus ring12and the surface temperature of the plate-like specimen W, and consequently, the in-plane temperature of the plate-like specimen W also becomes unstable.

When the convex part18is constituted of the plurality of the protruded strips18A,18B, . . . , the area of the convex parts18(the combined area of all of the protruded strips18A,18B, . . . ) is preferably 10% or more and 80% or less and more preferably 20% or more and 50% or less of the area of the groove17(the area of the bottom17aof the groove17) in a case in which the electrostatic chuck device10(the holder15) is seen in a planar view.

When the area of the convex parts18is less than 10% of the area of the groove17, the electrostatic adsorptive force acting between the protruded strips18A,18B, . . . and the focus ring12, that is, the force that attracts the focus ring12to the protruded strips18A,18B, . . . excessively weakens, and thus it is not possible to fix the focus ring12to the holder15. On the other hand, when the area of the convex parts18exceeds 80% of the area of the groove17, the space between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18becomes too small, and thus the amount of heat-transferring gas flowing through the space becomes small. As a result, the effect of cooling the focus ring12using heat-transferring gas becomes weak, and a difference is caused between the surface temperature of the focus ring12and the surface temperature of the plate-like specimen W, and consequently, the in-plane temperature of the plate-like specimen W also becomes unstable.

The distance between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18is preferably 1 μm or more and 10 μm or less and more preferably 2 μm or more and 5 μm or less.

When the distance between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18is less than 1 μm, the space between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18becomes too small, and thus the amount of heat-transferring gas flowing through the space becomes small. As a result, the effect of cooling the focus ring12using heat-transferring gas becomes weak, and a difference is caused between the surface temperature of the focus ring12and the surface temperature of the plate-like specimen W, and consequently, the in-plane temperature of the plate-like specimen W also becomes unstable. On the other hand, when the distance between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18exceeds 10 μm, the electrostatic adsorptive force acting between the protruded strips18A,18B, . . . and the focus ring12, that is, the force that attracts the focus ring12to the protruded strips18A,18B, . . . excessively weakens, and thus it is not possible to fix the focus ring12to the holder15.

The depth of the groove17needs to be set so that the flow of heat-transferring gas for cooling the focus ring12is not inhibited in the groove17and is preferably 10 μm to 50 μm.

The cooler13includes a heat-transferring gas provider19. The heat-transferring gas provider19is formed so that heat-transferring gas is provided to the groove17through a gas flow channel20communicated from the bottom17aat a predetermined pressure. Specifically, the gas flow channel20penetrates the mounting table11in the thickness direction of the mounting table and is communicated with a number of gas holes21provided on the bottom17aof the groove17. The gas holes21are formed on almost the entire surface of the bottom17aof the groove17.

To the gas flow channel20, a heat-transferring gas provision source22for providing heat-transferring gas is connected through a pressure control valve23. The pressure control valve23is a member for adjusting the flow amount so that the pressure of heat-transferring gas reaches a predetermined pressure. Meanwhile, the number of the gas flow channels20for providing heat-transferring gas from the heat-transferring gas provision source22maybe one or plural.

The electrostatic chuck part14in the mounting table11is schematically constituted of a circular dielectric layer24the upper surface (one main surface) of which is used as the placing surface (upper surface)24afor placing the plate-like specimen W such as a semiconductor wafer, a circular insulating layer25being placed opposite to the lower surface (the other main surface) of the dielectric layer24and having the same diameter as that of the dielectric layer24, a circular inner electrode for electrostatic adsorption26being sandwiched by the dielectric layer24and the insulating layer25and having a diameter smaller than those of the dielectric layer24and the insulating layer25, a terminal for power feeding27being connected to a central portion of the lower surface of the inner electrode for electrostatic adsorption26and applying a direct-current voltage, and a tubular insulating insulator28for insulating the terminal for power feeling by covering the periphery of the terminal for power feeding27.

The holder15in the mounting table11is schematically constituted of an annular dielectric layer24constituted of the banks16, the groove17, and the convex parts18, the annular insulating layer25being placed opposite to the lower surface of the dielectric layer24and having the same diameter as that of the dielectric layer24, and the annular inner electrode for electrostatic adsorption26being sandwiched by the dielectric layer24and the insulating layer25and having a diameter smaller than those of the dielectric layer24and the insulating layer25.

The respective layers constituting the electrostatic chuck part14and the respective layers constituting the holder15are in contact with each other. That is, the inner electrode for electrostatic adsorption26constituting the holder15is also electrically connected to the terminal for power feeding27.

A material for forming both the dielectric layer24and the insulating layer25is preferably heat-resistant ceramic, and the ceramic is preferably one type of ceramic selected from aluminum nitride (AlN), aluminum oxide (alumina, Al2O3), silicon nitride (Si3N4), zirconium oxide (ZrO2), yttrium oxide (Y2O3), sialon, boron nitride (BN), and silicon carbide (SiC) or complex ceramic consisting of two or more types selected from the group.

Particularly, in the dielectric layer24, the placing surface (upper surface)24aserves as an electrostatic adsorption surface, and thus it is preferable to select a material having a high dielectric constant and not acting as an impurity with respect to the plate-like specimen W to be electrostatically adsorbed, and, for example, a silicon carbide-aluminum oxide compound material (sintered body) including 4% by weight or more and 20% by weight or less of silicon carbide with aluminum oxide (alumina) as a remainder is preferred.

In addition, in order to form the banks16, the groove17, and the convex parts18having a predetermined size in the dielectric layer24in the electrostatic chuck part14, the material for forming the dielectric layer24preferably has an average crystal grain diameter of 10 μm or less and more preferably has an average crystal grain diameter of 2 μm or less. When the average crystal grain diameter in the material for forming the dielectric layer24is 10 μm or less, it is possible to form the banks16, the groove17, and the convex parts18in a predetermined size.

As the inner electrode for electrostatic adsorption26, a conductive ceramic flat plate having a thickness of approximately 10 μm to 50 μm is used. The volume intrinsic resistance value of the inner electrode for electrostatic adsorption26at the operation temperature of the electrostatic chuck device10is preferably 1.0×106Ω·cm or less and more preferably 1.0×104Ω·cm or less .

The focus ring12is made of an annular plate material having an inner diameter being slightly larger than the diameter of the electrostatic chuck part14. The focus ring12is electrostatically adsorbed to the banks16in the holder15.

The focus ring12is controlled so as to have the same temperature as that of the plate-like specimen W in treatment steps such as plasma etching, and thus, in a case in which the focus ring is used in oxide film etching, polycrystalline silicon, silicon carbide, or the like is preferably used as a material for the focus spring.

The mounting table main body11A is provided below the electrostatic chuck part14, the holder15, and the focus ring12and is a member for controlling the temperatures of the electrostatic chuck part144, the holder15, and the focus ring12to a desired temperature and additionally including an electrode for generating high frequencies. The mounting table main body has a flow channel29circulating a cooling medium such as water or an organic solvent formed therein and is constituted so as to be capable of maintaining the temperature of the plate-like specimen W being placed on the upper surface24aof the dielectric layer24to a desired temperature.

Examples of a material for forming the mounting table main body11A include metal having favorable thermal conductivity such as aluminum and compound materials made up of aluminum oxide (alumina, Al2O3) and silicon carbide (SiC).

In addition, below the insulating layer25, a heater (not illustrated) for controlling the temperature of the focus ring12to the same temperature as that of the plate-like specimen W by heating the temperature of the focus ring12to a predetermined temperature at an arbitrary temperature increase rate may be provided. In addition, a thermometer for measuring the temperature maybe connected to the heater or the focus ring12. Furthermore, a temperature controller and a heater power supply are connected to the thermometer.

As described above, according to the electrostatic chuck device10of the present embodiment, the holder15for electrostatically adsorbing the focus ring12has the pair of the banks16being provided along the circumferential direction of the focus ring12and being for placing the focus ring12and the annular groove17formed between these banks16, the cooler13provides heat-transferring gas to the groove17, the convex parts18are provided on the bottom17aof the groove17, the pair of the banks16are in contact with the focus ring12, the convex parts18are not in contact with the focus ring12, the pair of the banks16and the convex parts18electrostatically adsorb the focus ring12in a coordination fashion, or, in the pair of the banks16, the micro-protruding part16cincluding the plurality of the micro-protrusions16b,16b, . . . is formed on the surface16afacing the focus ring12, and the micro-protrusions16b,16b, . . . come into contact with the lower surface12aof the focus ring12when the focus ring12is placed on the holder15. Therefore, it is possible to increase the force for electrostatically adsorbing the focus ring12to the holder15(electrostatic adsorptive force), and consequently, the focus ring12can be sufficiently cooled using heat-transferring gas provided into the groove17by the cooler13. In addition, since the focus ring12is electrostatically adsorbed while the convex parts18do not come into contact with the focus ring12or only the micro-protrusions16b,16b, . . . in the banks16come into contact with the lower surface12aof the focus ring12, and thus the banks16electrostatically adsorb the focus ring12while the lower surface12aof the focus ring12does not come into contact with the surfaces16afacing the focus ring12in the banks16, in a state in which the focus ring12is electrostatically adsorbed, there is a space (void) between the lower surface12aof the focus ring12and the peak (upper surface)18aof the convex part18or between the lower surface12aof the focus ring12and the surface16afacing the focus ring12in the bank16, and thus it is possible to communicate heat-transferring gas provided into the groove17in this space, and the entire focus ring12can be uniformly cooled by the heat-transferring gas.

As a result, it is possible to adjust the temperature of the focus ring12and maintain the temperature of the focus ring12under treatments constant. Therefore, it is possible to stabilize the temperature of the outer circumferential part of the plate-like specimen W such as a silicon wafer and thus the etching characteristics in the plane of the plate-like specimen W can be uniformed.

In addition, since it is possible to accurately adjust the surface temperature of the focus ring12, a temperature difference between the surface temperature of the focus ring12and the surface temperature of the plate-like specimen W being placed on the electrostatic chuck part14can be eliminated, and thus it is possible to prevent accumulated substances from being accumulated on the focus ring12.

Meanwhile, in the present embodiment, a case in which the micro-protruding part16cincluding the plurality of the micro-protrusions16b,16b, . . . is formed on the surfaces16afacing the focus ring12in the pair of the banks16has been exemplified, but the present invention is not limited thereto. In the present embodiment, since the micro-protruding part including the plurality of the micro-protrusions is formed on the surface facing the focus ring in at least the bank on the outer circumferential position of the focus ring among the pair of the banks, in the pair of the banks, the amount of heat-transferring gas flowing out of the bank on the outer circumferential position of the focus ring becomes larger than the amount of heat-transferring gas flowing out of the other bank on the inner circumferential position of the focus ring.

In addition, in the present embodiment, a case in which the convex parts18are provided on the bottom17aof the annular groove17formed between the pair of the banks16has been exemplified, but the present invention is not limited thereto. In the present invention, the convex parts may not be provided on the bottom of the groove.

REFERENCE SIGNS LIST