ELECTROSTATIC CHUCK

Abstract

An electrostatic chuck can be manufactured at low cost and can securely prevent arcing even if the main body of the electrostatic chuck is thin. This electrostatic chuck is provided with an electrostatic chuck main body, an arcing prevention member, and a metal base member. The electrostatic chuck main body and the metal base member are provided with a plurality of vertical cooling gas holes. The arcing prevention member includes: a ceramic plate-shaped body through which a plurality of fine holes 20-100 μm in diameter pass; and an exterior member that secures the ceramic plate-shaped body and is disposed in an upper part of the vertical cooling gas holes. The ceramic plate-shaped body is thicker than the electrostatic chuck main body.

Claims

1. An electrostatic chuck comprising: a chuck body having a wafer placement surface which is disposed in a plasma processing apparatus and on which a wafer is electrostatically held; an anti-arcing member; and a metal base member supporting the chuck body, wherein: the chuck body and the metal base member are provided with a cooling gas hole, and a plurality of cooling gas-distributing vertical holes each connected to the cooling gas hole and penetrating therethrough to reach the wafer placement surface; and the anti-arcing member is comprised of a ceramic body through which a plurality of thin holes each having a diameter of 20 to 100 μm and serving as a cooling gas discharge passage penetrate, and disposed in an upper part of each of the plurality of cooling gas-distributing vertical holes, wherein the ceramic body has a thickness greater than that of the chuck body.

2. The electrostatic chuck as recited in claim 1, wherein the anti-arcing member has a columnar body, and wherein the plurality of thin holes are arranged parallel with respect to a central axis of the columnar body.

3. An electrostatic chuck comprising: a chuck body having a wafer placement surface which is disposed in a plasma processing apparatus and on which a wafer is electrostatically held; an anti-arcing member; and a metal base member supporting the chuck body, wherein: the chuck body and the metal base member are provided with a cooling gas hole, and a plurality of cooling gas-distributing vertical holes each connected to the cooling gas hole and penetrating therethrough to reach the wafer placement surface; and the anti-arcing member is comprised of a ceramic body through which a plurality of thin holes each having a diameter of 20 to 100 μm and serving as a cooling gas discharge passage penetrate, and an exterior member to which the ceramic body is fixed, and disposed in an upper part of each of the plurality of cooling gas-distributing vertical holes, wherein the ceramic body is separated into an inflow-side body fixed to a cooling-gas inflow side of the exterior member, and a discharge-side body fixed to a cooling-gas discharge side of the exterior member.

4. The electrostatic chuck as recited in claim 3, wherein the anti-arcing member has a columnar body, and wherein the plurality of thin holes each penetrating through the inflow-side body are arranged parallel and at a first distance with respect to the central axis of the columnar body, and the plurality of thin holes each penetrating through the discharge-side body are arranged parallel and at a second distance with respect to the central axis of the columnar body, wherein the first distance and the second distance are different distances.

5. The electrostatic chuck as recited in claim 3, wherein the inflow-side body and the discharge-side body are arranged with a gap of 1.1 mm or less therebetween.

6. The electrostatic chuck as recited in claim 3, wherein the exterior member is made of a ceramic material, and wherein the ceramic body is fixed to the exterior member by attaching means which is one selected from the group consisting of adhesive bonding, fitting engagement, and simultaneous sintering.

7. The electrostatic chuck as recited in claim 1, wherein the ceramic body has a relative density of 95% or more, wherein a pore lying in a sintered microstructure of the ceramic body is formed as closed pores which are free from continuous mutual contact, and wherein the ceramic body has a material strength of 400 MPa in terms of bending strength.

8. The electrostatic chuck as recited in claim 3, wherein the ceramic body has a relative density of 95% or more, wherein a pore lying in a sintered microstructure of the ceramic body is formed as closed pores which are free from continuous mutual contact, and wherein the ceramic body has a material strength of 400 MPa in terms of bending strength.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] FIG. 1 is a sectional view of an electrostatic chuck according to a first embodiment of the present invention.

[0042] FIG. 2 is sectional view of an upper part of a cooling gas-distribution vertical hole and the vicinity thereof in the first embodiment.

[0043] FIGS. 3A and 3B are, respectively, a sectional view and a top plan view of an anti-arcing member in the first embodiment.

[0044] FIG. 4 is sectional view of an upper part of a cooling gas-distribution vertical hole and the vicinity thereof in an electrostatic chuck according to a second embodiment of the present invention.

[0045] FIGS. 5A, 5B and 5C are, respectively, a sectional view, a top plan view and a bottom view of an anti-arcing member in the second embodiment.

[0046] FIGS. 6A and 6B are, respectively, a sectional view and a top plan view of an anti-arcing member in an electrostatic chuck according to a third embodiment of the present invention.

[0047] FIG. 7 is a sectional view of an electrostatic chuck described in the Patent Document 1.

[0048] FIG. 8 is a sectional view of an electrostatic chuck described in the Patent Document 2.

DESCRIPTION OF EMBODIMENTS

[0049] The present invention will now be described based on preferred embodiments thereof.

First Embodiment

[0050] An electrostatic chuck according to a first embodiment of the present invention illustrated in FIG. 1 comprises: a chuck body 1 having a wafer placement surface on which a wafer W is electrostatically held and having a thickness of about 1 mm; an anti-arcing member 2 having a thickness of about 2 mm; and a metal base member 3 supporting the chuck body 1.

[0051] The metal base member 3 is internally provided with a cooling gas hole 4 extending approximately horizontally, and the chuck body 1 and the metal base member 3 are provided with a plurality of cooling gas-distributing vertical holes 5 each connected to the cooling gas hole 4 and approximately vertically penetrating therethrough to reach the wafer placement surface.

[0052] Here, each of the cooling gas-distributing vertical holes 5 has a circular shape in horizontal section, and openings of the cooling gas-distributing vertical holes 5 on the wafer placement surface are arranged at approximately even intervals.

[0053] An internal electrode 6 is buried in the chuck body 1, and electrically connected to a high-voltage DC power source 7 to allow the wafer W to be electrostatically held on the wafer placement surface.

[0054] The metal base member 3 is also provided with a cooling water supply pipe 8 and a cooling water outlet pipe 9, whereby the metal base member 3 can be forcedly cooled, so that the chuck body 1 is cooled from the side of a lower surface thereof, and then the wafer W is cooled from the side of a lower surface thereof.

[0055] FIG. 2 is sectional view of an upper part of one of the cooling gas-distribution vertical holes 5 and the vicinity thereof in the first embodiment.

[0056] As shown in FIG. 2, a plurality of small protrusions 10 are formed on an upper surface of the chuck body 1, and upper surfaces of the small protrusions 10 serve as the wafer placement surface 11.

[0057] The anti-arcing member 2 is formed in a circular columnar shape, and attached to an upper part of the cooling gas-distribution vertical hole 5, wherein an outer surface of the anti-arcing member 2 is attached firmly to respective inner surfaces of the chuck body 1 and the metal base member 3 defining the upper part of the cooling gas-distribution vertical hole 5.

[0058] The anti-arcing member 2 is comprised of a columnar-shaped ceramic body 12 having a diameter of 1.2 mm, and a cylindrical sleeve-shaped exterior member 13 having an outer diameter of 1.8 mm and an inner diameter of 1.2 mm. The ceramic body 12 is fitted into the exterior member 13, such that an outer surface of the ceramic body 12 is attached firmly and fixed to an inner surface of the exterior member 13.

[0059] FIGS. 3A and 3B are, respectively, a sectional view and a top plan view of the anti-arcing member 2 in the first embodiment.

[0060] As shown in FIG. 3B, the ceramic body 12 is formed with: eight thin holes 14 arranged parallel and at a distance of 0.2 mm with respect to a central axis of the ceramic body 12; twelve thin holes 15 arranged parallel and at a distance of 0.3 mm with respect to the central axis; and eighteen thin holes 16 arranged parallel and at a distance of 0.4 mm with respect to the central axis.

[0061] Here, each of the thin holes 14, 15, 16 has a diameter of 50 μm.

[0062] The thin holes 14, 15, 16 formed in the ceramic body 12 can be fabricated by an apparatus and a method described in JP 5119353B which is a patented invention of the present applicant and a co-applicant.

[0063] Specifically, the thin holes is formed through a method comprising: a step (1) of preparing a kneaded material by mixing a raw material powder of a ceramic material, a binder for extrusion molding, and water; a step (2) of inserting a plurality of filaments each having a cavity in a longitudinal direction thereof and made of a synthetic resin, a carbon material or a metal material, across an extrusion molding die to which a filament guide and an orifice are assembled; a step (3) of supplying the kneaded material into the extrusion molding die while the filaments are pulled in a tensioned state, and extruding the kneaded material and the filaments from the orifice to obtain an extrusion-molded body containing the filaments in an axial direction thereof; a step (4) of cutting the extrusion-molded body into a given length to form a green body, or a step (4′) of cutting the extrusion-molded body into a given length, and pulling and removing the filaments the cut body to form a green body for a nozzle material; and a step (5) of, during burning of the green body obtained in the step (4) to attain degreasing and sintering, vaporizing and burning out the filaments made of a synthetic resin or a carbon material to form a plurality of straight through-holes each parallel to an axis of the resulting sintered body, or a step (5′) of subjecting the green body obtained in the step (4′) to degreasing and sintering to form a plurality of through-holes each parallel to an axis of the resulting sintered body (see, specifically, paragraphs [0022], [0023], [0031] to [0035] and [0054], and FIGS. 1, 2 and 6 of the above patent).

Second Embodiment

[0064] FIG. 4 is sectional view of an upper part of one of a plurality of cooling gas-distribution vertical holes 5 and the vicinity thereof in an electrostatic chuck according to a second embodiment of the present invention.

[0065] Except for the configuration of the upper part of the cooling gas-distribution vertical hole 5 and the vicinity thereof illustrated in FIG. 4, the electrostatic chuck according to the second embodiment has the same configuration as that of the electrostatic chuck according to the first embodiment illustrated in FIG. 1.

[0066] Therefore, in the following description, the same element or component as that in the first embodiment is assigned with the same reference sign as that used in the first embodiment, and description thereof will be omitted.

[0067] As shown in FIG. 4, a circular columnar-shaped anti-arcing member 20 is attached to the upper part of the cooling gas-distributing vertical hole 5, wherein an outer surface of the anti-arcing member 20 is attached firmly to the inner surfaces of the chuck body 1 defining the upper part of the cooling gas-distribution vertical hole 5.

[0068] The anti-arcing member 20 is composed of: a columnar-shaped ceramic discharge-side body 21 having a diameter of 1.6 mm and a thickness of 0.45 mm; a columnar-shaped ceramic inflow-side body 22 having a diameter of 1.2 mm and a thickness of 0.45 mm; and a cylindrical sleeve-shaped exterior member 23 having an outer diameter of 1.8 mm and a stepped portion provided on the side of an inner surface thereof. The ceramic discharge-side body 21 and the ceramic inflow-side body 22 are fitted, respectively, into an upper region and a lower region of the inner surface of the exterior member 23, and respective outer surfaces of the ceramic discharge-side body 21 and the ceramic inflow-side body 22 are attached firmly and fixed to the inner surface of the exterior member 23.

[0069] FIGS. 5A, 5B and 5C are, respectively, a sectional view, a top plan view and a bottom view of an anti-arcing member 20 in the second embodiment.

[0070] As shown in FIGS. 5B and 5C, the ceramic discharge-side body 21 is formed with: four thin holes 24 arranged parallel and at a distance of 0.15 mm with respect to a central axis of the ceramic discharge-side body 21; eight thin holes 25 arranged parallel and at a distance of 0.25 mm with respect to the central axis; sixteen thin holes 26 arranged parallel and at a distance of 0.35 mm with respect to the central axis; and twenty thin holes 27 arranged parallel and at a distance of 0.45 mm with respect to the central axis.

[0071] Further, the ceramic inflow-side body 22 is formed with: eight thin holes 14 arranged parallel and at a distance of 0.2 mm with respect to a central axis of the ceramic inflow-side body 22; twelve thin holes 15 arranged parallel and at a distance of 0.3 mm with respect to the central axis; and eighteen thin holes 16 arranged parallel and at a distance of 0.4 mm with respect to the central axis, in a manner similar to the ceramic body 12 in the first embodiment.

[0072] Here, each of the thin holes 14, 15, 16, 24, 25, 26, 27 has a diameter of 30 μm.

[0073] The thin holes 24, 25, 26, 27 formed in the ceramic discharge-side body 21 and the thin holes 14, 15, 16 formed in the ceramic inflow-side body 22 can be fabricated by the apparatus and the method described in the JP 5119353B which is a patented invention of the present applicant and a co-applicant, as with the first embodiment.

[0074] The ceramic discharge-side body 21 and the ceramic inflow-side body 22 are arranged with a gap of 0.1 mm therebetween, so that the gas is diffused therein. Further, the thin holes 14, 15, 16, 24, 25, 26, 27 are arranged at different distances with respect to the central axis. These make it possible to reliably prevent arcing even if the body is thinned,

Third Embodiment

[0075] FIGS. 6A and 6B are, respectively, a sectional view and a top plan view of an anti-arcing member 30 in an electrostatic chuck according to a third embodiment of the present invention.

[0076] Except for the configuration of the anti-arcing member 30 illustrated in FIGS. 6A and 6B, the electrostatic chuck according to the third embodiment has the same configuration as that of the electrostatic chuck according to the first embodiment.

[0077] Therefore, in the following description, the same element or component as that in the first embodiment is assigned with the same reference sign as that used in the first embodiment, and description thereof will be omitted.

[0078] The anti-arcing member 30 is comprised of a circular columnar-shaped ceramic body 32 having a diameter of 1.2 mm, and a cylindrical sleeve-shaped exterior member 33 having an outer diameter of 1.8 mm and an inner diameter of 1.2 mm. The ceramic body 32 is fitted into the exterior member 33, such that an outer surface of the ceramic body 32 is attached firmly and fixed to an inner surface of the exterior member 33.

[0079] As shown in FIGS. 6A and 6B, in the ceramic body 32, a line of four thin holes 34, a line of six thin holes 34, a line of eight thin holes 34, a line of eight thin holes 34, a line of eight thin holes 34, a line of eight thin holes 34, a line of six thin holes 34, and a line of four thin holes 34, are arranged parallel with respect to a central axis of the ceramic body 32, wherein a distance between adjacent two of the lines of thin holes 34 is 0.3 mm.

[0080] Here, each of the fifty-two thin holes 34 has a diameter of 50 μm.

[0081] The thin holes 34 formed in the ceramic body 32 can be fabricated by the apparatus and the method described in the JP 5119353B which is a patented invention of the present applicant and a co-applicant, as with the first embodiment.

[0082] Some modifications of the above embodiments will be enumerated as follows.

[0083] (1) In the first and third embodiments, each of the anti-arcing members 2, 30 is formed in a circular columnar shape, and the thickness thereof is set to be greater than that of the chuck body 1. However, the shape is not limited to the circular columnar shape, but may be a rectangular columnar shape or an elliptic columnar shape. Further, with regard to thickness, the thickness of only the ceramic body 12 or 32 to be fixed to the exterior member 13 or 33 may be set to be greater than that of the chuck body 1.

[0084] (2) In the first to third embodiments, a material for the exterior members 13, 23, 33 is not specified. However, from a viewpoint of anti-arcing, they are preferably made of an insulating material, more preferably, a ceramic material.

[0085] (3) In the first to third embodiments, fixing between the ceramic body 12 and the exterior member 13 is performed by fitting engagement. Alternatively, the fixing may be performed by adhesive bonding. Further, in a case where the exterior member 13 is made of a ceramic material, the fixing may be performed by simultaneous sintering.

[0086] Further, in FIGS. 2, 3A and 3B of the first embodiment and FIGS. 6A and 6B of the third embodiment, the anti-arcing member 2 or 30 in which the ceramic body 12 or 32 is fixed to the exterior member 13 or 33 is attached to each of the cooling gas-distributing vertical holes 5. Alternatively, the ceramic body 12 or 32 may be formed to have a diameter equal to an outer diameter of the exterior member 13 or 33, and directly attached to each of the cooling gas-distributing vertical holes 5.

[0087] In this case, the fixing between the ceramic body 12 or 32 and the exterior member 13 or 33 can be omitted, so that it is possible to further reduce the manufacturing cost.

[0088] (4) In the first to third embodiments, sizes and arrangements of the ceramic bodies 12, 32, the ceramic discharge-side body 21, the ceramic inflow-side body 22, the exterior members 13, 23, 33 and the thin holes 14, 15, 16, 24, 25, 26, 27, 34 are specified. However, as long as a sufficient amount of cooling gas can be supplied, they may be appropriately set in consideration of the diameter and arrangement of the thin holes, wherein it is necessary to ensure a flow rate of 0.4 sccm per 1000 mm.sup.2 as measured when a differential pressure is 1000 Pa.

[0089] Specifically, in the first and third embodiments, the thin hole may be provided in a number of 150 or more per 1000 mm.sup.2, and, in the second embodiment, the thin hole (in the ceramic inflow-side body 22) may be provided in a number of 400 or more per 1000 mm.sup.2.

[0090] From the viewpoint of anti-arcing, the diameter of the thin holes 14, 15, 16, 24, 25, 26, 27, 34 is preferably set in the range of 20 to 100 μm, more preferably 20 to 80 μm.

[0091] Further, an aspect ratio which is the ratio (L/D) of the length L to the diameter D of the thin hole is preferably set to 5 or more, more preferably 10 or more.

[0092] (5) In the first to third embodiments, all the thin holes 14, 15, 16, the thin holes 24, 25, 26, 27 and the thin holes 34 are arranged parallel with respect to the central axis. However, they do not necessarily have to be arranged parallel with respect to the central axis.

[0093] (6) In the first and third embodiments, in order to be adapted to a thin chuck body 1, the thickness of the ceramic body (2 or 30) is set to be greater than that of the chuck body 1. However, in a case where the chuck body 1 has a relatively large thickness of about 3 mm, the thickness of the ceramic body may be set to be less than that of the chuck body 1.

[0094] (7) In the second embodiment (FIGS. 4 and 5A to 5C), the two ceramic bodies (the ceramic discharge-side body 21 and the ceramic inflow-side body 22) are separately fixed. Alternatively, three or more ceramic bodies may be separately fixed.

[0095] (8) In the second embodiment, the ceramic discharge-side body 21 and the ceramic inflow-side body 22 are arranged with a gap of 0.1 mm therebetween. The magnitude of the gap may be appropriately changed.

[0096] Here, the gap may be set to 1.1 mm or less. Generally, the gap is selectively set in the range of 0.05 to 1 mm.

[0097] (9) In the second embodiment, the thickness of the anti-arcing member 20 is equal to that of the chuck body 1, and the outer surface of the anti-arcing member 20 is attached firmly to the inner surface of the chuck body 1. Alternatively, the thickness of the anti-arcing member 20 may be set to be less than or greater than that of the chuck body 1.

LIST OF REFERENCE SIGNS

[0098] 1: chuck body [0099] 2: anti-arcing member [0100] 3: metal base member [0101] 4: cooling gas hole [0102] 5: cooling gas-distributing vertical hole [0103] 6: internal electrode [0104] 7: high-voltage DC power supply [0105] 8: cooling water supply pipe [0106] 9: cooling water outlet pipe [0107] 10: small protrusion [0108] 11: wafer placement surface [0109] 12: ceramic body [0110] 13: exterior member [0111] 14 to 16: thin hole [0112] 20: anti-arcing member [0113] 21: ceramic discharge-side body [0114] 22: ceramic inflow-side body [0115] 23: exterior member [0116] 24 to 27: thin hole [0117] 30: anti-arcing member [0118] 32: ceramic body [0119] 33: exterior member [0120] 34: thin hole [0121] D: diameter of thin hole [0122] L: length of thin hole [0123] W: wafer