JP2016184645A - Electrostatic chuck device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel electrostatic chuck device capable of enhancing the processing accuracy of a wafer.SOLUTION: An electrostatic chuck device includes a mounting table 11 provided with a mounting surface, an annular focus ring 12 surrounding the mounting surface, and cooling means for cooling the mounting table 11 and focus ring 12. The mounting table 11 has a holding part 15 provided around the mounting surface in the circumferential direction of the focus ring 12, and attracting the focus ring 12 electrostatically. The holding part 15 has a pair of banks 16 provided in the circumferential direction, and mounting the focus ring 12, and an annular groove 17 formed between the pair of banks 16. Cooling means supplies a heat-transfer gas G to the groove 17, and an electrostatic chuck device 10A is provided so that the amount of the heat-transfer gas G flowing out from the first bank 16A, out of the pair of banks 16, located on the outer peripheral side of the focus ring 12 is larger than the amount flowing out from the second bank 16B located on the inner peripheral side of the focus ring 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrostatic chuck device.

  In recent years, in semiconductor manufacturing processes, plasma processing such as plasma etching and plasma CVD has been frequently used because microfabrication with high efficiency and large area is possible as devices are highly integrated and have high performance.

  2. Description of the Related Art In a semiconductor manufacturing apparatus that performs a plasma process, an electrostatic chuck device that can easily attach and fix a wafer to a sample stage and can maintain the wafer at a desired temperature is used. The electrostatic chuck device includes a ring member (focus ring) disposed on the outer peripheral edge of the wafer attracting portion so as to surround the wafer loading surface.

  By the way, in the conventional semiconductor manufacturing apparatus, when the wafer fixed to the electrostatic chuck apparatus is irradiated with plasma, the surface temperature of the wafer rises. Therefore, in order to suppress an increase in the surface temperature of the wafer, a cooling medium such as water is circulated through the temperature adjusting base portion of the electrostatic chuck device to cool the wafer from the lower side.

  In such an electrostatic chuck device, by providing the second electrostatic chucking means for attracting the focus ring to the outer peripheral portion of the wafer, the focus ring is moved from the force for attracting the wafer to the electrostatic chuck portion. There is known a configuration in which the temperature of the focus ring is adjusted by adsorbing with a large force and blowing a cooling medium (cooling gas) onto the back surface of the focus ring (see, for example, Patent Document 1).

  In addition, a technique is known in which a gas supply unit is provided in each of the wafer adsorption unit and the focus ring adsorbed by the electrostatic chuck unit, and the temperatures of the wafer adsorption unit and the focus ring are independently controlled (for example, , See Patent Document 2).

  According to these techniques, the wafer surface temperature can be made uniform, and the wafer processing accuracy can be improved.

JP 2002-033376 A JP 2012-134375 A

  However, the techniques described in Patent Documents 1 and 2 have room for improvement in that the wafer surface temperature is made uniform and the wafer processing accuracy is improved. Therefore, there has been a demand for an electrostatic chuck device that can further improve the wafer processing accuracy.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a novel electrostatic chuck device capable of improving the processing accuracy of a wafer.

  In order to solve the above-described problem, an embodiment of the present invention includes a mounting table provided with a mounting surface on which a plate-like sample is mounted, and a table placed on the mounting table and surrounding the mounting surface. An annular focus ring, the mounting table and a cooling means for cooling the focus ring, wherein the mounting table is provided around the mounting surface along a circumferential direction of the focus ring, and the focus ring The holding portion is provided along the circumferential direction, and is formed between the pair of bank portions on which the focus ring is placed and the pair of bank portions. An annular groove portion, and the cooling means supplies heat transfer gas to the groove portion, and the heat transfer gas is supplied from a first bank portion located on the outer peripheral side of the focus ring among the pair of bank portions. The amount of effluent flows out of the pair of embankments. Providing an electrostatic chuck device provided so much made of the amount flowing out of the second bank portion located on the inner circumferential side of Kasuringu.

  According to an aspect of the present invention, at least in the first bank portion, on the surface facing the focus ring, a gas outflow portion that allows the heat transfer gas supplied to the groove portion to flow out of the groove portion. It is good also as a structure provided.

  According to an aspect of the present invention, the gas outflow portion intersects the first bank portion at a contact portion where the focus ring and a surface of the first bank portion facing the focus ring are in contact with each other. It is good also as a structure which is the groove | channel provided in the direction.

  According to one aspect of the present invention, the opening area of the groove may be gradually reduced from an end portion on the groove portion side toward an outer end portion of the groove portion.

  According to one aspect of the present invention, a part of the groove including at least an outer end portion of the groove portion extends downward when the surface direction of the mounting surface is a horizontal direction. Also good.

  According to an aspect of the present invention, the gas outflow portion is a first microprojection portion including a plurality of first microprojections, and the plurality of first microprojections are in contact with the focus ring, and the focus ring is It is good also as composition which carries out electrostatic adsorption.

  According to an aspect of the present invention, the gas outflow portion is a porous layer made of a porous material, the porous layer is in contact with the focus ring, electrostatically adsorbs the focus ring, The pores of the porous layer may be configured to communicate in the width direction of the bank portion.

  According to an aspect of the present invention, the gas outflow portion is provided on a surface facing the focus ring in both of the pair of bank portions, and the porous body layer provided in the first bank portion includes: It is good also as a structure with a larger porosity than the said porous body layer provided in the said 2nd bank part.

  According to an aspect of the present invention, the gas outflow portion is provided on a surface facing the focus ring in both of the pair of bank portions, and a width of a surface facing the focus ring in the first bank portion. May be configured to be narrower than the width of the surface facing the focus ring in the second bank portion.

  According to an aspect of the present invention, in the focus ring, a gas outflow portion that causes the heat transfer gas supplied to the groove portion to flow out of the groove portion is provided at least on a surface facing the first bank portion. It is good also as the structure currently formed.

  According to an aspect of the present invention, the gas outflow portion is provided on a surface of the focus ring facing both the first bank portion and the second bank portion, and includes a plurality of second microprojections. The separation distance between the plurality of second microprojections provided at positions facing the first bank is a plurality of the second protrusions disposed at positions facing the second bank. It is good also as a structure wider than the separation distance of 2 microprotrusions.

  According to an aspect of the present invention, the gas outflow portion is provided on a surface of the focus ring facing both the first bank portion and the second bank portion, and includes a plurality of second microprojections. The plurality of second protrusions, which are two minute protrusions, wherein the heights of the plurality of second minute protrusions provided at positions facing the first bank part are opposed to the second bank part. It is good also as a structure higher than a microprotrusion.

  According to an aspect of the present invention, the gas outflow portion is provided on a surface of the focus ring facing both the first bank portion and the second bank portion, and includes a plurality of second microprojections. 2 microprojections, and the width of the first bank may be narrower than the width of the second bank.

  According to an aspect of the present invention, the focus ring is provided so as to protrude outward from an outer periphery of a surface of the first bank portion facing the focus ring in a plan view, and the first bank portion is provided in the focus ring. The outer end of the surface facing the surface may extend downward when the surface direction of the mounting surface is a horizontal direction.

  ADVANTAGE OF THE INVENTION According to this invention, the novel electrostatic chuck apparatus which can improve the processing precision of a wafer can be provided.

It is a schematic sectional drawing which shows the electrostatic chuck apparatus of 1st Embodiment. It is a schematic sectional drawing which shows the electrostatic chuck apparatus of 1st Embodiment. It is explanatory drawing of the electrostatic chuck apparatus which concerns on the modification of 1st Embodiment. It is explanatory drawing of the electrostatic chuck apparatus which concerns on 2nd Embodiment. It is explanatory drawing of the electrostatic chuck apparatus which concerns on 3rd Embodiment. It is explanatory drawing of the electrostatic chuck apparatus which concerns on 4th Embodiment. It is explanatory drawing of the electrostatic chuck apparatus which concerns on 5th Embodiment.

[First Embodiment]
Hereinafter, an electrostatic chuck device according to a first embodiment of the present invention will be described with reference to FIGS. In all the drawings below, the dimensions and ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

FIG. 1 is a schematic cross-sectional view showing the electrostatic chuck device of the present embodiment. The electrostatic chuck device 10 of the present embodiment includes a mounting table 11 provided with a mounting surface (a mounting surface (upper surface) 24a of a dielectric layer 24 described later) on which the plate-like sample W is mounted, The ring-shaped focus ring 12 that is arranged on the top and surrounds the periphery of the mounting surface (mounting surface 24a), and the cooling means 13 that cools the mounting table 11 and the focus ring 12 are roughly configured.
Hereinafter, it demonstrates in order.

(Mounting table)
The mounting table 11 is provided on the mounting table main body 11A, the mounting table main body 11A, a disk-shaped electrostatic chuck portion 14 having a mounting surface (mounting surface 24a), and a mounting surface (mounting surface 24a). ) And a holding portion 15 that is provided along the circumferential direction of the focus ring 12 and electrostatically attracts the focus ring 12. The configuration of the holding unit 15 will be described in detail later.

(Mounting table body)
The mounting table main body 11A is provided below the electrostatic chuck unit 14, the holding unit 15 and the focus ring 12, and controls the temperature of the electrostatic chuck unit 14, the holding unit 15 and the focus ring 12 to a desired temperature. In addition, a high-frequency generating electrode is also provided, and a flow path 29 for circulating a cooling medium such as water or an organic solvent is formed therein, and the upper surface (mounting surface 24a) of the dielectric layer 24 described above. It is possible to maintain the temperature of the plate-like sample W placed on the desired temperature.

Examples of the material for forming the mounting table main body 11A include a metal having good thermal conductivity such as aluminum, and a composite material made of aluminum oxide (alumina, Al ₂ O ₃ ) and silicon carbide (SiC).

  Further, below the insulating layer 25, the temperature of the focus ring 12 is controlled to the same temperature as the plate-like sample W by heating the temperature of the focus ring 12 to a predetermined temperature at an arbitrary rate of temperature increase. A heater (not shown) may be provided. Further, a thermometer for measuring these temperatures may be connected to the heater and the focus ring 12. Furthermore, a temperature controller and a heater power source may be connected to the thermometer.

(Electrostatic chuck)
The electrostatic chuck portion 14 of the mounting table 11 includes a circular dielectric layer 24 whose upper surface (one main surface) is a mounting surface (upper surface) 24a for mounting a plate-like sample W such as a semiconductor wafer, The dielectric layer 24 is disposed opposite to the lower surface (another main surface), and is sandwiched between the dielectric layer 24 and the insulating layer 25 having the same diameter as the dielectric layer 24. A circular electrostatic internal electrode 26 having a smaller diameter than the layer 24 and the insulating layer 25; a power supply terminal 27 that is connected to the central portion of the lower surface of the electrostatic internal electrode 26 and applies a DC voltage; It is schematically constituted by a cylindrical insulator 28 which covers the periphery of the service terminal 27 and is insulated from the outside.

The material for forming the dielectric layer 24 and the insulating layer 25 is preferably a heat-resistant ceramic. Examples of the ceramic include aluminum nitride (AlN), aluminum oxide (alumina, Al ₂ O ₃ ), and silicon nitride (Si ₃ N _4). ), Zirconium oxide (ZrO ₂ ), yttrium oxide (Y ₂ O ₃ ), sialon, boron nitride (BN) and silicon carbide (SiC), or a composite ceramic containing two or more types Is preferred.

  In particular, the dielectric layer 24 is made of a material having a high dielectric constant that does not become an impurity with respect to the plate-like sample W to be electrostatically attracted because the mounting surface (upper surface) 24a side is an electrostatic attracting surface. For example, a silicon carbide-aluminum oxide composite material (sintered body) containing 4% by weight or more and 20% by weight or less of silicon carbide with the balance being aluminum oxide (alumina) is preferable.

  In addition, in order to form the dielectric layer 24 constituting the electrostatic chuck portion 14 in the holding portion 15 having a predetermined shape and size as described later, the forming material of the dielectric layer 24 has an average crystal grain size of 10 μm. Or less, more preferably 2 μm or less. If the average crystal grain size of the forming material of the dielectric layer 24 is 10 μm or less, the holding portion 15 can be formed in a predetermined size.

As the internal electrode 26 for electrostatic adsorption, a plate-shaped ceramic having a conductivity of about 5 μm to 50 μm is used. The volume specific resistance value of the internal electrode 26 for electrostatic adsorption at the operating temperature of the electrostatic chuck device 10 is preferably 1.0 × 10 ⁶ Ω · cm or less, more preferably 1.0 × 10 ⁴ Ω · cm. cm or less.

Examples of the conductive ceramics constituting the internal electrode 26 for electrostatic adsorption include silicon carbide (SiC) -aluminum oxide (Al ₂ O ₃ ) composite sintered body, tantalum nitride (TaN) -aluminum oxide (Al ₂ O ₃ ). Examples thereof include a composite sintered body, a tantalum carbide (TaC) -aluminum oxide (Al ₂ O ₃ ) composite sintered body, a molybdenum carbide (Mo ₂ C) -aluminum oxide (Al ₂ O ₃ ) composite sintered body, and the like.

(Focus ring)
The focus ring 12 is made of an annular plate material whose inner diameter is slightly larger than the diameter of the electrostatic chuck portion 14. The focus ring 12 is controlled so as to have the same temperature as the plate-like sample W in a processing step such as plasma etching, and the material thereof is, for example, polycrystalline silicon, carbonized when used for oxide film etching. Silicon or the like is preferably used.

(Holding part)
The holding portion 15 is provided along the circumferential direction of the focus ring 12, and includes a pair of bank portions 16 on which the focus ring 12 is placed, and an annular groove portion 17 formed between the pair of bank portions 16. Have. The holding portion 15 includes an annular dielectric layer 24 formed as a bank portion 16, a groove portion 17, and a convex portion 18, and an annular insulating layer 25 having the same diameter as that of the dielectric layer 24. The ring-shaped electrostatic attraction internal electrode 26 is sandwiched between the dielectric layer 24 and the insulating layer 25 and has a smaller diameter than the dielectric layer 24 and the insulating layer 25.

  Each layer constituting the electrostatic chuck portion 14 and each layer constituting the holding portion 15 are connected. That is, the internal electrode 26 for electrostatic attraction constituting the holding portion 15 is also electrically connected to the power supply terminal 27.

  As will be described later, a heat transfer gas for cooling the focus ring 12 is supplied to the groove portion 17. The depth of the groove portion 17 is such that the flow of the heat transfer gas is not inhibited in the groove portion 17, preferably 10 μm to 50 μm, more preferably 35 μm to 40 μm, and preferably 13 μm to 15 μm. More preferably, it is most preferably 10 μm to 12 μm.

  When the focus ring 12 is placed on the holding unit 15, the pair of bank portions 16 contacts the lower surface of the focus ring 12. In this state, the holding unit 15 electrostatically attracts the focus ring 12 by applying the electrostatic attracting internal electrode 26.

(Cooling means)
The cooling means 13 includes a heat transfer gas supply unit 19. The heat transfer gas supply unit 19 supplies the heat transfer gas to the groove portion 17 at a predetermined pressure via the gas flow path 20 communicating from the bottom surface 17a side. Specifically, the gas flow path 20 penetrates the mounting table 11 in the thickness direction and communicates with a number of gas holes 21 provided in the bottom surface 17 a of the groove portion 17. The gas hole 21 is formed on substantially the entire bottom surface 17 a of the groove portion 17.

  A heat transfer gas supply source 22 for supplying heat transfer gas is connected to the gas flow path 20 via a pressure control valve 23. The pressure control valve 23 adjusts the flow rate so that the pressure of the heat transfer gas becomes a predetermined pressure. In addition, the number of the gas flow paths 20 that supply the heat transfer gas from the heat transfer gas supply source 22 may be one or more.

  Incidentally, the electrostatic chuck device is usually installed inside a vacuum chamber and used in a vacuum environment. If there is a gap between the focus ring 12 and the bank portion 16 in a vacuum environment, heat may not be transferred from the focus ring 12 to the bank portion 16 in the gap portion, and the focus ring 12 may not be cooled sufficiently. . For example, the opposing surfaces of the focus ring 12 and the bank portion 16 are not parallel due to molding errors, and are formed at such positions when the distance between the opposing surfaces gradually increases toward the outside of the groove portion 17. In the gap, heat is not transmitted from the focus ring 12 to the bank portion 16.

  On the other hand, in the electrostatic chuck device of the present invention, the heat transfer gas supplied from the cooling means 13 to the groove portion 17 flows out of the groove portion 17 from between the focus ring 12 and the bank portion 16. When the heat transfer gas flows out, the heat transfer gas existing between the focus ring 12 and the bank portion 16 assists the heat transfer between the focus ring 12 and the bank portion 16, so that the temperature of the focus ring 12 is set. It becomes easier to control.

  Furthermore, in the electrostatic chuck device of the present invention, the amount of heat transfer gas flowing out from the bank portion (first bank portion 16A) located on the outer peripheral side of the focus ring 12 is a pair of bank portions 16. It is provided so that it may be larger than the amount which flows out from the bank part (2nd bank part 16B) located in the inner peripheral side of the focus ring 12 among the parts 16. FIG.

  FIG. 2 is a schematic cross-sectional view of the electrostatic chuck device 10 of the present embodiment, and is a partially enlarged view in which a region indicated by α in FIG. 1 is enlarged.

  The electrostatic chuck device 10 </ b> A (electrostatic chuck device 10) according to the present embodiment supplies the heat transfer gas G supplied to the groove portion 17 to the outside of the groove portion 17 on the surface of the focus ring 12 that faces the first bank portion 16 </ b> A. A gas outflow portion 30A is provided for outflow.

  The gas outflow portion 30 </ b> A is a groove provided in the focus ring 12. 30 A of gas outflow parts are provided in the direction which cross | intersects the 1st bank part 16A in the contact part which the focus ring 12 and the surface facing the focus ring 12 of the 1st bank part 16A contact, and the groove part 17 side is provided. The end portion opens into the groove portion 17. The inner surface 31 of the gas outflow portion 30A is downward from the groove portion 17 side toward the outer side of the groove portion 17 when the surface direction of the mounting surface 24a (see FIG. 1) is a horizontal direction (broken line indicated by reference numeral S in the figure). It is a slope inclined to. Further, the opening area of the gas outflow portion 30A gradually decreases from the end portion on the groove portion 17 side toward the outer end portion of the groove portion 17.

  The first bank portion 16A and the focus ring 12 are separated by the gas outflow portion 30A, and the electrostatic attraction force between the first bank portion 16A and the focus ring 12 is between the second bank portion 16B and the focus ring 12. It is weaker than the electrostatic adsorption force.

  In the electrostatic chuck device 10A, by having the gas outflow part 30A having such a configuration, the heat transfer gas G supplied to the groove part 17 has priority from the first bank part 16A side over the second bank part 16B side. Thus, it flows out of the groove portion 17. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Further, since the inner surface 31 is a slope inclined downward, when the heat transfer gas G flows out from the groove portion 17, the heat transfer gas G is discharged downward in the horizontal direction. Therefore, the heat transfer gas G is less likely to reach the space above the placement surface 24a, and the plasma generated in the space above the placement surface 24a is less likely to be adversely affected. Therefore, the processing accuracy of the plate-like sample W can be improved.

  Further, since the opening area of the gas outflow portion 30A is gradually reduced from the end portion on the groove portion 17 side toward the outer end portion of the groove portion 17, the heat transfer gas G flows from the end portion on the groove portion 17 side to the groove portion 17 side. Pressurized toward the outer end. Thereby, when the opening area of the gas outflow portion 30A is constant from the end portion on the groove portion 17 side to the outer end portion of the groove portion 17, or gradually increases from the end portion on the groove portion 17 side to the outer end portion of the groove portion 17. Compared with the case where it does, heat transfer gas G is discharged | emitted vigorously from the outer edge part of 30 A of gas outflow parts. Therefore, the heat transfer gas G is less likely to reach the space above the placement surface 24a, and the plasma generated in the space above the placement surface 24a is less likely to be adversely affected. Therefore, the processing accuracy of the plate-like sample W can be improved.

  As shown in FIG. 2, the bottom surface 17 a of the groove portion 17 is provided with a convex portion 18 that protrudes (in the thickness direction of the holding portion 15) on the surface side of the bank portion 16 on which the focus ring 12 is placed. It may be.

The convex part 18 is comprised from several columnar protrusion 18A, 18B, ..., for example.
The protrusions 18A, 18B,... Are spaced apart from each other. The protrusions 18A, 18B,... Are provided over the entire area of the groove portion 17 when the electrostatic chuck device 10 (holding portion 15) is viewed in plan. The space | interval of protrusion 18A, 18B, ... is not specifically limited.

  Moreover, the convex part 18 may be comprised from several ridge part 18A, 18B, ..., for example. The ridges 18A, 18B,... Are provided apart from each other. The ridges 18A, 18B,... May form a continuous ring along the ring-shaped groove 17 when the electrostatic chuck device 10 (holding unit 15) is viewed in plan, or at intervals. It may have a discontinuous arc shape provided. When the ridges 18 </ b> A, 18 </ b> B,... Form a continuous ring along the annular groove 17, the ridges 18 </ b> A, 18 </ b> B, ... are provided concentrically with the groove 17. The interval between the ridges 18A, 18B,... Is not particularly limited.

  The convex portion 18 does not contact the focus ring 12. There is also a space (gap) between the lower surface 12 a of the focus ring 12 and the apex (upper surface) 18 a of the convex portion 18.

  Further, the size of the space (gap) between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18, that is, the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18. Although the distance between is not particularly limited, the distance between the focus ring 12 and the projection 18 is such that an electrostatic attraction force acts.

  When the convex portion 18 is composed of a plurality of projections 18A, 18B,..., The area of the convex portion 18 (the area combining all the projections 18A, 18B,...) Is the electrostatic chuck device 10 (holding portion). When 15) is viewed in plan, it is preferably 10% or more and 80% or less, more preferably 20% or more and 50% or less of the area of the groove part 17 (the area of the bottom surface 17a of the groove part 17).

  If the area of the convex part 18 is less than 10% of the area of the groove part 17, the electrostatic attraction force acting between the protrusions 18A, 18B,... And the focus ring 12, that is, the protrusions 18A, 18B,. Since the force for attracting the focus ring 12 is too weak, the focus ring 12 cannot be fixed to the holding portion 15. On the other hand, if the area of the convex portion 18 exceeds 80% of the area of the groove portion 17, the space between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 becomes too small. The amount of heat transfer gas flowing through the is reduced. As a result, the effect of cooling the focus ring 12 by the heat transfer gas is reduced, and a difference occurs between the surface temperature of the focus ring 12 and the surface temperature of the plate-like sample W. As a result, the surface of the plate-like sample W The internal temperature also becomes unstable.

  When the convex portion 18 is composed of a plurality of convex strip portions 18A, 18B,..., The area of the convex portion 18 (area combining the convex strip portions 18A, 18B,...) Is an electrostatic chuck device. 10 (holding part 15) in plan view is preferably 10% or more and 80% or less, and more preferably 20% or more and 50% or less of the area of the groove part 17 (the area of the bottom surface 17a of the groove part 17). More preferred.

  If the area of the convex part 18 is less than 10% of the area of the groove part 17, the electrostatic attraction force acting between the convex part 18A, 18B,... And the focus ring 12, that is, the protrusions 18A, 18B,. Since the force for attracting the focus ring 12 is too weak, the focus ring 12 cannot be fixed to the holding portion 15. On the other hand, if the area of the convex portion 18 exceeds 80% of the area of the groove portion 17, the space between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 becomes too small. The amount of heat transfer gas flowing through the is reduced. As a result, the effect of cooling the focus ring 12 by the heat transfer gas is reduced, and a difference occurs between the surface temperature of the focus ring 12 and the surface temperature of the plate-like sample W. As a result, the surface of the plate-like sample W The internal temperature also becomes unstable.

  The separation distance between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 5 μm or less.

  When the separation distance between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 is less than 1 μm, the space between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 is small. Therefore, the amount of heat transfer gas flowing through the space is reduced. As a result, the effect of cooling the focus ring 12 by the heat transfer gas is reduced, and a difference occurs between the surface temperature of the focus ring 12 and the surface temperature of the plate-like sample W. As a result, the surface of the plate-like sample W The internal temperature also becomes unstable. On the other hand, when the separation distance between the lower surface 12a of the focus ring 12 and the apex (upper surface) 18a of the convex portion 18 exceeds 10 μm, the electrostatic force acting between the convex strip portions 18A, 18B,. Since the attracting force, that is, the force that attracts the focus ring 12 to the protrusions 18A, 18B,... Is too weak, the focus ring 12 cannot be fixed to the holding portion 15.

  According to the electrostatic chuck device configured as described above, the processing accuracy of the plate-like sample W can be improved.

  In the present embodiment, the gas outflow portion 30A is provided in the focus ring 12, but it may be provided in the first bank portion 16A.

  FIG. 3 is an explanatory view of an electrostatic chuck device 10B according to a modification of the present embodiment, and is a plan view showing a part of the first bank portion 16A.

  As shown in the figure, a gas outflow portion 30B for allowing the heat transfer gas G supplied to the groove portion 17 to flow out of the groove portion 17 is provided on the upper surface of the first bank portion 16A, that is, the surface facing the focus ring 12. It is good to be.

  The gas outflow portion 30B is a groove provided in the first bank portion 16A. 30 A of gas outflow parts are provided in the direction which cross | intersects the 1st bank part 16A in the contact part which the focus ring 12 and the surface facing the focus ring 12 of the 1st bank part 16A contact, and the groove part 17 side is provided. The end portion opens into the groove portion 17. The opening area of the gas outflow portion 30B gradually decreases from the end portion on the groove portion 17 side toward the outer end portion of the groove portion 17. For example, as shown in the figure, the opening width W1 of one end (the end on the groove 17 side) is formed wider than the opening width W2 of the other end (the outer end of the groove 17).

  Since the electrostatic chuck device 10B has such a gas outflow portion 30B, the heat transfer gas G supplied to the groove portion 17 is preferentially grooved from the first bank portion 16A side than the second bank portion 16B side. 17 flows out to the outside. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Further, since the opening area of the gas outflow portion 30B gradually decreases from the end portion on the groove portion 17 side toward the outer end portion of the groove portion 17, for the same reason as the gas outflow portion 30A, the heat transfer gas G Is expelled to the outside from the outer end of the gas outlet 30A. Therefore, the heat transfer gas G is less likely to reach the space above the placement surface 24a, and the plasma generated in the space above the placement surface 24a is less likely to be adversely affected. Therefore, the processing accuracy of the plate-like sample W can be improved.

  Even with the electrostatic chuck device 10B having such a configuration, the processing accuracy of the plate-like sample W can be improved.

[Second Embodiment]
FIG. 4 is an explanatory diagram of an electrostatic chuck device 10C according to the second embodiment of the present invention, and corresponds to FIG. The electrostatic chuck device 10C of this embodiment is partially in common with the electrostatic chuck device 10A of the first embodiment. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  As shown in the figure, in the electrostatic chuck device 10 </ b> C, a gas outflow portion 30 </ b> C is formed on a surface 16 a facing the focus ring 12 in the pair of bank portions 16. The gas outflow portion 30C is a first minute protrusion including a plurality of first minute protrusions 16b, 16b.

  When the focus ring 12 is placed on the holding portion 15, the first minute protrusions 16b, 16b... Are in contact with the focus ring 12 at the apexes. That is, there is a space (gap) between the lower surface 12 a of the focus ring 12 and the surface 16 a of the bank portion 16 that faces the focus ring 12. In other words, the lower surface 12a of the focus ring 12 and the surface 16a of the bank 16 facing the focus ring 12 are not in contact with each other, and only the first minute protrusions 16b, 16b,. It contacts the lower surface 12a.

  In this state, the holding unit 15 electrostatically attracts the focus ring 12 by applying the electrostatic attracting internal electrode 26.

  The size of the space (gap) between the lower surface 12a of the focus ring 12 and the surface 16a facing the focus ring 12 in the bank portion 16, that is, the surface 16a facing the focus ring 12 in the bank portion 16 is used as a reference. The height of the first microprotrusions 16b, 16b... Is not particularly limited, but is such that the heat transfer gas supplied into the groove portion 17 by the cooling means 13 can flow.

  In the electrostatic chuck apparatus 10C, the gas outflow portion (first minute protrusion) 30C is a surface facing the focus ring 12 in both of the pair of bank portions 16 (the first bank portion 16A and the second bank portion 16B). 16a. Further, the width of the surface 16a facing the focus ring 12 in the first bank portion 16A (indicated by the symbol Wa in the drawing) is the width of the surface 16a facing the focus ring 12 in the second bank portion 16B (reference symbol in the drawing). Narrower than Wb).

  Since the electrostatic chuck device 10C has such a gas outflow portion 30C, the heat transfer gas G supplied to the groove portion 17 is larger from the first bank portion 16A side than the second bank portion 16B side. It flows out to the outside. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Even with the electrostatic chuck device 10 </ b> C having such a configuration, the processing accuracy of the plate-like sample W can be improved.

  In the electrostatic chuck device 10C shown in the figure, the gas outflow portion (first minute protrusion) 30C is provided on both the first bank portion 16A and the second bank portion 16B. It is good also as providing only in. In that case, the width Wa of the surface 16a facing the focus ring 12 in the first bank portion 16A may be the same as the width Wb of the surface 16a facing the focus ring 12 in the second bank portion 16B.

[Third Embodiment]
FIG. 5 is an explanatory diagram of an electrostatic chuck device 10D according to the third embodiment of the present invention, and corresponds to FIG.

  As shown in the figure, in the electrostatic chuck device 10D, a gas outflow portion 30D is formed on a surface 16a facing the focus ring 12 in the pair of bank portions 16.

  The gas outflow portion 30D is a porous body layer that uses a porous body as a forming material. A porous body layer 33 is provided on the surface 16a facing the focus ring 12 in the first bank portion 16A. A porous body layer 34 is provided on the surface 16a facing the focus ring 12 in the second bank portion 16B.

  The porous layer 33 and the porous layer 34 are made of, for example, a sprayed film or a porous ceramic. The heights of the porous body layer 33 and the porous body layer 34 are not particularly limited, but are set such that an electrostatic adsorption force acts between the focus ring 12 and the bank portion 16.

  The pores of the porous layer 33 and the porous layer 34 communicate with each other in the width direction of the bank portion 16, in other words, in the direction connecting the inside and the outside of the groove portion 17. Further, the porous body layer 33 provided in the first bank portion 16A has a higher porosity than the porous body layer 34 provided in the second bank portion 16B.

  Here, the “porosity” is the ratio of the total volume of the pores to the predetermined unit volume of the porous body layer. The porosity may be a value obtained from the ratio between the true density of the material for forming the porous body layer and the apparent density of the porous body layer, and is a value obtained by actually measuring the volume of the pores per unit volume. There may be. A porous layer with a higher porosity has more holes and the heat transfer gas is likely to flow out.

  Since the electrostatic chuck device 10D has such a gas outflow part 30D, the heat transfer gas G supplied to the groove part 17 is larger from the first bank part 16A side than the second bank part 16B side. It flows out to the outside. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Even with the electrostatic chuck device 10D having such a configuration, the processing accuracy of the plate-like sample W can be improved.

  In the electrostatic chuck device 10D, the width of the surface 16a facing the focus ring 12 in the first bank portion 16A is smaller than the width of the surface 16a facing the focus ring 12 in the second bank portion 16B. Good.

  Further, in the electrostatic chuck device 10D shown in the figure, the gas outflow portion 30D is provided in both the first bank portion 16A and the second bank portion 16B, but it may be provided only in the first bank portion 16A. .

[Fourth Embodiment]
FIG. 6 is an explanatory diagram of an electrostatic chuck device 10E according to the fourth embodiment of the present invention, and corresponds to FIG.

  As shown in the drawing, in the electrostatic chuck device 10E, a gas outflow portion 30E is formed on a surface (lower surface) 12a facing the bank portion 16 in the focus ring 12E (focus ring 12). The gas outflow portion 30E is a second minute protrusion including a plurality of second minute protrusions 12b, 12b.

  When the focus ring 12E is placed on the holding portion 15, the second minute protrusions 12b, 12b... Are in contact with the bank portion 16 at the apex. That is, there is a space (gap) between the lower surface 12a of the focus ring 12E and the surface 16a of the bank portion 16 facing the focus ring 12E. In other words, the lower surface 12a of the focus ring 12E and the surface 16a facing the focus ring 12E in the bank portion 16 are not in contact with each other, and only the second minute protrusions 12b, 12b. It contacts the surface 16a.

  In this state, the holding unit 15 electrostatically attracts the focus ring 12 </ b> E by applying the electrostatic attracting internal electrode 26.

  The size of the space (gap) between the lower surface 12a of the focus ring 12E and the surface 16a facing the focus ring 12E in the bank portion 16, that is, the lower surface 12a facing the bank portion 16 in the focus ring 12E is used as a reference. The heights of the second minute protrusions 12b, 12b,... Are not particularly limited, but are such that the heat transfer gas supplied into the groove portion 17 by the cooling means 13 can flow.

  In the electrostatic chuck device 10E, the gas outflow portion (second microprojection portion) 30E is a lower surface facing both of the pair of bank portions 16 (the first bank portion 16A and the second bank portion 16B) in the focus ring 12E. 12a.

  In the electrostatic chuck device 10E having such a gas outflow portion 30E, the width Wa of the surface 16a facing the focus ring 12E in the first bank portion 16A is the surface 16a facing the focus ring 12E in the second bank portion 16B. It may be narrower than the width Wb.

  In addition, the separation distance between the plurality of second minute protrusions 12b, 12b... Provided at positions facing the first bank part 16A is the plurality of second minute protrusions 12b provided on the second bank part 16B. 12b... May be wider than the distance between them. By setting it as such a structure, the heat transfer gas supplied in the groove part 17 by the cooling means 13 is more from the 1st bank part 16A side where the separation distance of 2nd microprotrusion 12b, 12b ... is wide. Many leak out.

  In addition, in the position facing 16 A of 1st bank part, although the separation distance of 2nd microprotrusion 12b, 12b ... is not specifically limited, a heat transfer gas is 1st bank rather than the 2nd bank part 16B side. It is set to such an extent that more can flow out from the part 16A side.

  Further, the heights of the plurality of second minute protrusions 12b, 12b,... Provided on the first bank portion 16A are higher than those of the plurality of second minute protrusions 12b, 12b,. May be higher. With such a configuration, the heat transfer gas supplied into the groove portion 17 by the cooling means 13 is more from the first bank portion 16A side where the heights of the second minute protrusions 12b, 12b,. It flows out to the outside.

  In addition, in the position facing 16 A of 1st bank part, although the height of 2nd microprotrusion 12b, 12b ... is not specifically limited, a heat transfer gas is the 1st bank part rather than the 2nd bank part 16B side. From the 16A side, it is set to such an extent that it can flow out to the outside more.

  Since the electrostatic chuck device 10E has such a gas outflow portion 30E, more heat transfer gas G is supplied to the groove portion 17 from the first bank portion 16A side than the second bank portion 16B side. It flows out to the outside. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Even with the electrostatic chuck device 10E having such a configuration, the processing accuracy of the plate-like sample W can be improved.

  In the electrostatic chuck device 10E shown in the figure, the gas outflow portion (second minute protrusion) 30E is provided at both the position facing the first bank portion 16A and the position facing the second bank portion 16B. However, it is good also as providing only in the position which opposes the 1st bank part 16A.

[Fifth Embodiment]
FIG. 7 is an explanatory diagram of an electrostatic chuck device 10F according to the fifth embodiment of the present invention, and corresponds to FIG.

  In the electrostatic chuck device 10F of the present embodiment, any of the gas outflow portions 30A to 30E described above can be employed. In FIG. 7, the gas outflow portion is not shown.

  In addition, in the electrostatic chuck device 10F, the focus ring 12F (focus ring 12) is provided so as to protrude outward from the outer periphery of the surface 16a facing the focus ring 12F of the first bank portion 16A in plan view. Further, in the focus ring 12, the outer end portion 12X of the lower surface 12a facing the first bank portion 16A has a horizontal direction (broken line indicated by reference numeral S in the drawing) of the mounting surface 24a (see FIG. 1). When it is extended downwards.

  In the electrostatic chuck device 10F having such a focus ring 12F, the heat transfer gas flowing out from the first bank portion 16A side is discharged downward. Therefore, the heat transfer gas G that has flowed out does not easily reach the space above the placement surface 24a (see FIG. 1), and does not easily affect the plasma generated in the space above the placement surface 24a. It is possible to improve the machining accuracy.

  Even with the electrostatic chuck device 10F having such a configuration, the processing accuracy of the plate-like sample W can be improved.

  In the first to fifth embodiments described above, the amount of heat transfer gas flowing out from the first bank portion 16A is larger than the amount flowing out of the second bank portion 16B. Although the gas outflow portions 30A to 30E, which are structures, are provided in the facing portion between the bank portion 16A and the focus ring 12, the present invention is not limited thereto. For example, the amount of heat transfer gas flowing out from the first bank portion 16A can be made larger than the amount flowing out from the second bank portion 16B by changing the configuration of the electrodes of the electrostatic chuck portion 14. .

  That is, the area where the electrostatic adsorption internal electrode 26 and the first bank portion 16A overlap in plan view is smaller than the area where the electrostatic adsorption internal electrode 26 and the second bank portion 16B overlap in plan view. Alternatively, the electrostatic adsorption internal electrode 26 may be formed. In such a configuration, the adsorption force between the electrostatic adsorption internal electrode 26 and the first bank portion 16A tends to be weaker than the adsorption force between the electrostatic adsorption internal electrode 26 and the second bank portion 16B. When the hot gas is supplied into the groove portion 17, the focus ring 12 tends to float on the first bank portion 16 </ b> A side due to the internal pressure in the groove portion 17. As a result, the amount of heat transfer gas flowing out from the first bank portion 16A tends to be larger than the amount flowing out of the second bank portion 16B.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  G ... Heat transfer gas, W ... Plate-like sample 10, 10A, 10B, 10C, 10D, 10E, 10F ... Electrostatic chuck device, 11 ... Mounting table, 12, 12E, 12F ... Focus ring, 12b ... Second minute Projection, 12X ... end, 13 ... cooling means, 15 ... holding part, 16 ... bank, 16A ... first bank, 16a ... surface, 16b ... first microprojection, 16B ... second bank, 17 ... groove , 18A ... projection, 24a ... placement surface, 30A, 30B, 30C, 30D, 30E ... gas outflow part, 30C ... gas outflow part (first microprojection part), 30E ... gas outflow part (second microprojection part) , 33, 34 ... porous layer, Wa, Wb ... width

Claims (14)

A mounting table provided with a mounting surface for mounting a plate-like sample;
An annular focus ring disposed on the mounting table and surrounding the mounting surface;
Cooling means for cooling the mounting table and the focus ring,
The mounting table includes a holding unit that is provided around the mounting surface along the circumferential direction of the focus ring and electrostatically attracts the focus ring.
The holding portion is provided along the circumferential direction, and has a pair of bank portions on which the focus ring is placed, and an annular groove portion formed between the pair of bank portions,
The cooling means supplies heat transfer gas to the groove,
The amount of the heat transfer gas flowing out from the first bank portion located on the outer peripheral side of the focus ring in the pair of bank portions is a second position located on the inner peripheral side of the focus ring in the pair of bank portions. An electrostatic chuck device provided to be larger than the amount flowing out from the bank portion.   The gas outflow part which flows out the said heat transfer gas supplied to the said groove part out of the said groove part is provided in the surface facing the said focus ring at least in the said 1st bank part. Electrostatic chuck device.   The gas outflow portion is a groove provided in a direction intersecting the first bank portion at a contact portion where the focus ring and a surface of the first bank portion facing the focus ring are in contact with each other. Item 3. The electrostatic chuck device according to Item 2.   The electrostatic chuck device according to claim 3, wherein an opening area of the groove is gradually reduced from an end portion on the groove portion side toward an outer end portion of the groove portion.   5. The electrostatic chuck according to claim 3, wherein a part of the groove including at least an outer end of the groove extends downward when the surface direction of the mounting surface is a horizontal direction. 6. apparatus. The gas outflow portion is a first microprojection including a plurality of first microprojections,
The electrostatic chuck device according to claim 2, wherein the plurality of first minute protrusions are in contact with the focus ring and electrostatically attract the focus ring. The gas outflow part is a porous body layer having a porous body as a forming material,
The porous body layer is in contact with the focus ring and electrostatically adsorbs the focus ring;
The electrostatic chuck device according to claim 2, wherein the pores of the porous body layer communicate with each other in the width direction of the bank portion. The gas outflow portion is provided on a surface facing the focus ring in both of the pair of bank portions,
The electrostatic chuck device according to claim 7, wherein the porous body layer provided in the first bank portion has a larger porosity than the porous body layer provided in the second bank portion. The gas outflow portion is provided on a surface facing the focus ring in both of the pair of bank portions,
The static electricity according to any one of claims 6 to 8, wherein a width of a surface facing the focus ring in the first bank portion is narrower than a width of a surface facing the focus ring in the second bank portion. Chuck device.   The gas outflow part which flows out the said heat transfer gas supplied to the said groove part out of the said groove part is formed in the surface which faces the said 1st bank part at least in the said focus ring. Electrostatic chuck device. The gas outflow portion is a second microprojection portion including a plurality of second microprojections provided on a surface of the focus ring facing both the first bank portion and the second bank portion,
The distance between the plurality of second minute protrusions provided at the position facing the first bank is the distance between the plurality of second minute protrusions provided at the position facing the second bank. The electrostatic chuck device according to claim 10, wherein the electrostatic chuck device is wider. The gas outflow portion is a second microprojection portion including a plurality of second microprojections provided on a surface of the focus ring facing both the first bank portion and the second bank portion,
The plurality of second minute protrusions provided at positions facing the first bank portion are higher than the plurality of second minute protrusions provided at positions facing the second bank portion. The electrostatic chuck device according to claim 10 or 11. The gas outflow portion is a second microprojection portion including a plurality of second microprojections provided on a surface of the focus ring facing both the first bank portion and the second bank portion,
13. The electrostatic chuck device according to claim 10, wherein a width of the first bank portion is narrower than a width of the second bank portion. The focus ring is provided so as to protrude outward from the outer periphery of the surface of the first bank portion facing the focus ring in plan view,
The outer end of the surface facing the first bank portion in the focus ring extends downward when the surface direction of the mounting surface is a horizontal direction. The electrostatic chuck device according to claim 1.

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