Electrostatic chuck and wafer processing apparatus

An electrostatic chuck includes a ceramic dielectric substrate having a first major surface on which an object to be processed is mounted, and a second major surface, the ceramic dielectric substrate being a polycrystalline ceramic sintered body, an electrode layer provided on the ceramic dielectric substrate, a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, and a heater provided between the electrode layer and the base plate. The base plate includes a through hole piercing the base plate and a communication path passing a medium adjusting a temperature of the object to be processed, and when viewed in a direction perpendicular to the first major surface, at least a part of the heater exists on a side of the through hole as viewed from a first portion of the communication path which is closest to the through hole.

TECHNICAL FIELD

An aspect of the invention generally relates to an electrostatic chuck and a wafer processing apparatus.

BACKGROUND ART

Electrostatic chucks are used as means to adhere and hold an object to be processed (such as a semiconductor wafer or a glass substrate) in a plasma processing chamber that performs etching, chemical vapor deposition (CVD), sputtering, ion implantation, ashing, and the like.

Electrostatic chucks are fabricated by interposing an electrode between ceramic substrates of alumina or the like and sintering the arrangement. Electrostatic chucks apply an electrostatic adhesion-use power to the internal electrode and thereby adhere a substrate such as a silicon wafer or the like by an electrostatic force.

Recently, in an etching apparatus based on plasma, there is a trend of higher output of plasma. With the higher output of plasma, the heat amount supplied to the wafer is increased. In the case where the heat amount supplied to the plasma is relatively low, a temperature change of the electrostatic chuck is relatively small and a relatively small chiller is available. In the case where the heat amount supplied to the wafer is relatively low, use of a cooling metal plate which does not need a coolant and change of the chiller temperature are sufficiently available so that the wafer is set to a desired temperature in the processing.

However, as the heat amount supplied to the wafer is relatively increased and the temperature of the ceramic base material is increased, the temperature of the wafer is increased. Then, there is a problem that materials which can be used for the wafer processing are limited to high heat resistance material.

On the other hand, there is an electrostatic chuck having a built-in heater for uniformization of the temperature distribution in the plane of the wafer.

Uniformity of the temperature distribution in the plane of the wafer is desired.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The invention has been made based on the recognition of such a problem, and an object of the invention is to provide an electrostatic chuck and a wafer processing apparatus capable of improving uniformity of the temperature distribution in a plane of an object to be processed.

Solution to Problem

According to one embodiment of the invention, an electrostatic chuck is provided. The electrostatic chuck includes a ceramic dielectric substrate having a first major surface on which an object to be processed is mounted, and a second major surface on a side opposite to the first major surface, the ceramic dielectric substrate being a polycrystalline ceramic sintered body, an electrode layer provided on the ceramic dielectric substrate, a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, and a heater provided between the electrode layer and the base plate. The base plate includes a through hole piercing the base plate and a communication path passing a medium adjusting a temperature of the object to be processed, and when viewed in a direction perpendicular to the first major surface, at least a part of the heater exists on a side of the through hole as viewed from a first portion of the communication path which is closest to the through hole.

DESCRIPTION OF EMBODIMENT

A first aspect of the invention is an electrostatic chuck including a ceramic dielectric substrate having a first major surface on which an object to be processed is mounted, and a second major surface on a side opposite to the first major surface, the ceramic dielectric substrate being a polycrystalline ceramic sintered body, an electrode layer provided on the ceramic dielectric substrate, a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, and a heater provided between the electrode layer and the base plate, the base plate including a through hole piercing the base plate and a communication path passing a medium adjusting a temperature of the object to be processed, and when viewed in a direction perpendicular to the first major surface, at least a part of the heater existing on a side of the through hole as viewed from a first portion of the communication path which is closest to the through hole.

According to this electrostatic chuck, the uncontrollable range of temperature adjustment within the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved. Also in the vicinity of the through hole, a region of cool spot hardest to heat is substantially equal to a region of hot spot hardest to cool, and thus equilibrium between heating and cooling is easily achieved, and the uniformity of the temperature distribution in the plane of the object to be processed can be improved.

A second aspect of the invention is an electrostatic chuck according to the first aspect of the invention, wherein when viewed in a perpendicular direction to the first major surface, a distance between the first portion and a center axis of the through hole is larger than a distance between a second portion of the heater closest to the through hole and the center axis of the through hole.

According to the electrostatic chuck, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved.

A third aspect of the invention is an electrostatic chuck according to the second aspect of the invention, wherein when viewed in the direction perpendicular to the first major surface, a distance between a center of a first virtual circle passing the first portion and any two portions on the side of the through hole of the communication path and a center of a second virtual circle passing the second portion and any two portions on the side of the through hole of the heater is not more than 0.2 millimeters.

According to the electrostatic chuck, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved.

A fourth aspect of the invention is an electrostatic chuck according to the third aspect of the invention, wherein when viewed in the direction perpendicular to the first major surface, a center of a first virtual circle passing the first portion and any two portions on the side of the through hole of the communication path overlaps a center of a second virtual circle passing the second portion and any two portions on the side of the through hole of the heater.

According to the electrostatic chuck, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved.

A fifth aspect of the invention is an electrostatic chuck according to one of the second to fourth aspects of the invention, wherein when viewed in the direction perpendicular to the first major surface, a width of the communication path in the first portion is wider than a width of the heater in the second portion.

According to the electrostatic chuck, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved.

A sixth aspect of the invention is an electrostatic chuck according to the third or fourth aspect of the invention, wherein when viewed in the direction perpendicular to the first major surface, a length of a portion where the second virtual circle crosses the heater is not less than 50 percent and not more than 80 percent of a length of circle perimeter of the second virtual circle.

According to the electrostatic chuck, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved.

A seventh aspect of the invention is an electrostatic chuck according to one of the first to sixth aspects of the inventions, wherein the heater includes a first heater having a first folded-back portion bent from a first direction to a second direction different from the first direction, and a second heater having a second folded-back portion provided to be close to the first heater and bent from a third direction to a fourth direction different from the third direction, a distance of closest approach between the first folded-back portion and the second folded-back portion is not less than 50 percent and less than 100 percent of a distance between a round end portion of the first folded-back portion and a round end portion of the second folded-back portion.

According to the electrostatic chuck, the distance of closest approach between the multiple heaters131is defined in order to define a density of the space portion141in the portion of the closest folded-back portions131eof the multiple heaters131, and thus the temperature controllability of the object to be processed W can be improved and the uniformity of the temperature distribution of the object to be processed can be improved.

An eighth aspect of the invention is an electrostatic chuck according to one of the first to seventh aspects of the invention, wherein when viewed in the direction perpendicular to the first major surface, a ratio of an area of the heater to an area of the ceramic dielectric substrate is not less than 20% and not more than 80%.

According to the electrostatic chuck, the uniformity of the temperature distribution in the plane of the object to be processed can be improved by arranging the heaters with an adequate density.

A ninth aspect of the invention is an electrostatic chuck according to one of the first to eighth aspects of the invention, wherein when viewed in the direction perpendicular to the first major surface, a ratio of an area of the communication path to an area of the ceramic dielectric substrate is not less than 20% and not more than 80%.

According to the electrostatic chuck, the uniformity of the temperature distribution in the plane of the object to be processed can be improved by arranging the communication paths with an adequate density.

A tenth aspect of the invention is an electrostatic chuck according to one of the first to ninth aspects of the invention, wherein when viewed in the direction perpendicular to the first major surface, a ratio of an area of the heater to an area of the communication path is not less than 60% and not more than 180%.

According to the electrostatic chuck, the uniformity of the temperature distribution in the plane of the object to be processed can be improved by arranging both of the communication paths and the heaters with an adequate density.

An eleventh aspect of the invention is an electrostatic chuck according to one of the first to tenth aspects of the invention, further including a plurality of bypass electrodes provided between the electrode layer and the base plate and electrically connected to the heater, a distance between mutually adjacent bypass electrodes of the plurality of bypass electrodes being not less than 0.05 millimeters and not more than 10 millimeters.

According to the electrostatic chuck, the freedom of arrangement of the terminal62and the heater131can be improved by providing the bypass electrode. Furthermore, ununiformity of heat conduction due to a gap between the bypass electrodes is suppressed by defining a gap width between the bypass electrodes. Thereby, the uniformity of the temperature distribution of the object to be processed can be improved.

A twelfth aspect of the invention is an electrostatic chuck according to one of the first to tenth aspects of the invention, further including a plurality of bypass electrodes provided between the electrode layer and the base plate and electrically connected to the heater, a length along the direction perpendicular to the first major surface of a region between mutually adjacent bypass electrodes of the plurality of bypass electrodes being not less than 0.01 millimeters and not more than 1 millimeter.

According to the electrostatic chuck, the freedom of arrangement of the terminal62and the heater131can be improved by providing the bypass electrode. Furthermore, ununiformity of heat conduction due to a gap between the bypass electrodes is suppressed by defining a gap width between the bypass electrodes. Thereby, the uniformity of the temperature distribution of the object to be processed can be improved.

A thirteenth aspect of the invention is a wafer processing apparatus including the electrostatic chuck according to one of the first to twelfth aspects of the invention.

According to the wafer processing apparatus, the uniformity of the temperature distribution of the object to be processed can be improved.

Embodiments of the invention will now be described with reference to the drawings. Note that the same numerals are applied to similar constituent elements in the drawings and detailed descriptions of such constituent elements are appropriately omitted.

FIG. 1is a schematic cross-sectional view illustrating the configuration of an electrostatic chuck according to the embodiment.

As shown inFIG. 1, an electrostatic chuck100according to the embodiment includes a ceramic dielectric substrate11, an electrode layer12, a heater131, and a base plate50. The ceramic dielectric substrate11is attached on the base plate50.

The ceramic dielectric substrate11is, for example, a flat plate-like substrate made of a polycrystalline ceramic sintered body, and includes a first major surface11aon which an object to be processed W such as a semiconductor wafer or the like is mounted, and a second major surface11bon a side opposite the first major surface11a.

The material of the crystals included in the ceramic dielectric substrate11may include, for example, Al2O3, Y2O3and YAG. By using this material, it is possible to increase the transmittivity of infrared light, the insulation resistance, and the plasma durability of the ceramic dielectric substrate11.

The electrode layer12is interposed between the first major surface11aand the second major surface11b. In other words, the electrode layer12is formed so as to be inserted into the ceramic dielectric substrate11. The electrode layer12is integrally sintered with the ceramic dielectric substrate11. An electrostatic chuck substrate110is a plate-like structure that includes the ceramic dielectric substrate11and the electrode layer12provided in the ceramic dielectric substrate11.

The electrode layer12is not limited to be interposed between the first major surface11aand the second major surface11b, and may be attached to the second major surface11b. Thus, the electrode layer12is not limited to be integrally sintered with the ceramic dielectric substrate11.

The electrostatic chuck100applies an adhere and hold voltage80to the electrode layer12, thereby generating charge on the first major surface11aside of the electrode layer12and using a resulting electrostatic force to adhere and hold the object to be processed W. A heater current133passes through a heater electrode current introduction portion132, thereby the heater131generates heat and can increase the temperature of the object to be processed W.

The ceramic dielectric substrate11includes a first dielectric layer111between the electrode layer12and the first major surface11a, and a second dielectric layer112between the electrode layer12and the second major surface11b. For example, the heater131is included in the second dielectric layer112. However, the form of the heater is not limited to an internal type, but it may be produced by forming a concave portion in the first dielectric layer111or the second dielectric layer112and connecting a heater metal thereto, or by connecting or laminating a dielectric body that includes a heater to the second dielectric layer. Also, there is no limitation to the shape of a heater electrode current introduction part132, a metal embedding, joint, or shape.

In the electrostatic chuck shown inFIG. 1, the heater131is provided on a side of the electrode layer12from the second major surface11b. However, the heater131may be provided at the same position as the second major surface11b, and may be provided on an opposite side to the electrode layer12as viewed from the second major surface11b.

In the case where the heater131is provided on the electrode layer12side from the second major surface11b, for example, the heater may be included in a sintered body formed by sintering stacked green sheets on which the electrode and the heater are printed.

In the case where the heater is provided at the same position as the second major surface11b, for example, the heater may be formed by an appropriate method such as screen printing or the like on the second major surface11b, or may be formed by PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition) or the like.

In the embodiment, it is sufficient that the heater131can be used for controlling the temperature distribution in the plane of the object to be processed W, the position and the structure or the like of the heater131are not particularly limited. For example, the heater may be provided inside the ceramic dielectric substrate11, or may be provided as a member different from the ceramic dielectric substrate11. The heater131may be interposed between the base plate50and the ceramic dielectric substrate11. The heater131may be a plate of a conductor or an insulator, or a heater plate including a thermoelectric element. The heater131may be included in the ceramic, and the second major surface11bside of the ceramic dielectric substrate11may be coated. A manufacturing method of the heater131is not particularly limited.

In the description of the embodiment, the direction that joins the second major surface11band the first major surface11ais denoted as the Z direction, one of the directions perpendicular to the Z direction is denoted as the X direction, and the direction perpendicular to the Z direction and the X direction is denoted as the Y direction.

The electrode layer12is provided along the first major surface11aand the second major surface11b. The electrode layer12is an adhering electrode for adhering and holding the object to be processed W. The electrode layer12may be a unipolar type or a bipolar type. Also, the electrode layer12may be a tripolar type or another multi-polar type. The number electrode layers12and the arrangement of electrode layers12are selected as appropriate. The electrode layer12shown inFIG. 1is of the bipolar type, and the electrode layer12of two poles is provided in the same plane.

It is favorable that at least the first dielectric layer111of the ceramic dielectric substrate11has an infrared spectral transmittance of not less than 20%. In the embodiment, the infrared spectral transmittance is the value in terms of a thickness of 1 mm.

By making the infrared spectral transmittance of at least the first dielectric layer111of the ceramic dielectric substrate11not less than 20%, the infrared light emitted from the heater131when the object to be processed W is mounted on the first major surface11acan efficiently pass through the ceramic dielectric substrate11. Therefore, it is difficult for heat to accumulate in the object to be processed W, and the controllability of the temperature of the object to be processed W is increased.

For example, if the electrostatic chuck100is used within a chamber where plasma processing is carried out, the temperature of the object to be processed W can easily rise as the plasma power is increased. In the electrostatic chuck100according to the embodiment, the heat transmitted to the object to be processed W by the plasma power is efficiently transmitted to the ceramic dielectric substrate11. In addition, heat that has been transmitted to the ceramic dielectric substrate11by the heater131is efficiently transmitted to the object to be processed W. Therefore, the object to be processed W can be efficiently heated and maintained at its desired temperature.

In the electrostatic chuck100according to this embodiment, preferably, the infrared spectral transmittance of the second dielectric layer112is not less than 20%, in addition to the first dielectric layer111. By making the infrared spectral transmittance of the first dielectric layer111and the second dielectric layer112not less than 20%, the infrared light emitted from the heater131is more efficiently transmitted through the ceramic dielectric substrate11, so it is possible to improve the controllability of the temperature of the object to be processed W.

As described above, the ceramic dielectric substrate11is attached to the base plate50. When attaching the ceramic dielectric substrate11to the base plate50, a heat-resistant resin such as silicone or the like, indium bonding, brazing, or the like can be used. The bonding material is selected as appropriately based on the range of temperature used, cost, and the like, but more preferably, the bonding material easily transmits infrared light.

The base plate50is, for example, divided into an upper portion50aand a lower portion50bmade of aluminum. Brazing, electron beam welding, and diffusion bonding or the like can be used for connection of an upper portion50aand a lower portion50b. However, a manufacturing method of the base plate50is not limited to the above.

A communication path55is provided in a boundary portion between the upper portion50aand the lower portion50b. That is, the communication path55is provided inside the base plate50. One end of the communication path55is connected to an input path51. The other end of the communication path55is connected to an output path52.

The base plate50plays the role of adjusting the temperature of the ceramic dielectric substrate11. For example, when the ceramic dielectric substrate11is cooled, a cooling medium is caused to flow into the communication path55through the input path51, pass through the communication path55, and flow out from the communication path50through the output path52. Accordingly, heat from the base plate50is absorbed by the cooling medium, and the ceramic dielectric substrate11attached to the base plate50can be cooled.

On the other hand, when the ceramic dielectric substrate11is heated, a heating medium can be supplied within the communication path55. Alternatively, the heater131can be included in the base plate50. In this way, when the temperature of the ceramic dielectric substrate11is adjusted by the base plate50, the temperature of the object to be processed W adhered and held by the electrostatic chuck100can be easily adjusted.

In the cross section ofFIG. 1, a horizontal dimension Dh (corresponding to a width D3described later) of the communication path55is smaller than a vertical dimension Dv (a length along the Z-direction) of the communication path55. Thereby, while improving the controllability of the range where the medium adjusting the temperature flows, a ratio of a region provided with the communication path55as viewed along a direction perpendicular to the first major surface11acan be high. For example, while suppressing a pressure loss of the medium adjusting the temperature, the in-plane uniformity of the temperature of the object to be processed W can be improved.

Also, on the first major surface11aside of the ceramic dielectric substrate11, protrusions13are provided as required, and grooves14are provided between the protrusions13. The grooves14are in communication, and spaces are formed between a rear surface of the object to be processed W mounted on the electrostatic chuck100and the grooves14.

The grooves14are connected to introduction paths53which pierce through the base plate50and the ceramic dielectric substrate11. When a transfer gas such as helium (He) or the like is introduced from introduction paths53with the object to be processed W in a state of being adhered and held, the transfer gas flows into the space provided between the object to be processed W and the grooves14, and the object to be processed W can be directly heated or cooled by the transfer gas.

The base plate50is provided with a through hole57such as a lift pin hole and a sensor hole, for example. The lift pin hole (the through hole57on a right side of the introduction path53inFIG. 1) pierces the base plate50and the ceramic dielectric substrate11. A pin (not shown) removing the object to be processed W placed on the first major surface11afrom the electrostatic chuck100is inserted into the lift pin hole. The sensor hole (the through hole57on a left side of the introduction path53inFIG. 1) pierces the base plate50. The sensor (not shown) sensing the temperature of the ceramic dielectric substrate11is installed in the sensor hole. That is, the through hole57sometimes pierces the base plate50and the ceramic dielectric substrate11, on the other hand sometimes pierces the base plate50without piercing the ceramic dielectric substrate11. The through hole57is not limited to the lift pin hole and the sensor hole or the like.

A connection portion20is provided on the second major surface11band the second major surface11bof the ceramic dielectric substrate11. A contact electrode61is provided in the upper portion50aof the base plate50in a position corresponding to the position of the connection portion20. Hence, when the electrostatic chuck100is attached to the upper portion50aof the base plate50, the contact electrode61contacts the connection portion20and electrical conduction can thereby be obtained between the contact electrode61and the electrode layer12via the connection portion20.

For the contact electrode61, a moveable probe may, for example, be used. Accordingly, a reliable connection is obtained between the contact electrode61and the connection portion20, and damage to the connection portion20caused by the contact of the contact electrode61and the connection portion20can be minimized. It is noted that the contact electrode61is not limited to that described above, and may take any form. The contact electrode61may simply contact the connection portion20, or engage with or be screwed into the connection portion20.

FIG. 2is a schematic plan view showing a vicinity of a through hole of the embodiment.

FIG. 2is a schematic plan view of the electrostatic chuck100as viewed in a direction of an arrow A shown inFIG. 1. In other words,FIG. 2is a schematic plan view of the electrostatic chuck100as viewed in a direction perpendicular to the first major surface11a. It is noted that, in the schematic plan view shown inFIG. 2, the heater131and the communication path55are shown by solid lines instead of broken lines for convenience of description.

As shown inFIG. 2, when viewed in the direction perpendicular to the first major surface11a, at least a part of the heater131exists on a side of the through hole57as viewed from a portion (first portion)55aof the communication path55closest to the through hole57. “The portion closest to the through hole57” is referred to as, for example, a portion closest to a center axis57aof the through hole57as viewed in the direction perpendicular to the first major surface11a. In the communication path55shown inFIG. 2, the portion closest to the through hole57is the portion55a.

When viewed in the direction perpendicular to the first major surface11a, a distance D1between the center axis57aof the through hole57and the portion55aof the communication path55closest to the through hole57is longer than a distance D2between the center axis57aof the through hole57and a portion (second portion)131aof the heater131closest to the through hole57.

When viewed in the direction perpendicular to the first major surface11a, a width D3of the communication path55in the portion55aof the communication path55closest to the through hole57is wider than a width D4of the heater131in the portion131aof the heater131closest to the through hole57. The width D3is, for example, about not less than 5 millimeters (mm) and approximately not more than 10 mm. The width D4is, for example, about not less than 0.5 mm and approximately not more than 3 mm.

When viewed in the direction perpendicular to the first major surface11a, a diameter D7(seeFIG. 3) of the through hole57is, for example, not less than 0.05 mm and not more than 10 mm.

When viewed in the direction perpendicular to the first major surface11a, it is desired that a part including the portion131aof the heater131and a part including the portion55aof the communication path55are in a shape surrounding the through hole57. The shape surrounding the through hole57is referred to as an outward convex shape as seen from the through hole57, and is desired to be in a generally circular arc having the through hole57as a center.

As shown inFIG. 2, when viewed in the direction perpendicular to the first major surface11a, a circle approximated by the inner (side of the through hole57) diameter of the heater131is defined as a second virtual circle C2. Alternatively, as shown inFIG. 2, when viewed in the direction perpendicular to the first major surface11a, a circle passing the portion131aof the heater131closest to the through hole57and any two portions (inFIG. 2, portion131band portion131c) on the side of the trough hole57(inside) the heater131is defined as a second virtual circle C2. At this time, a length of the portion (inFIG. 2, circular arc CA1and circular arc CA2) where the second virtual circle C2crosses the heater131is not less than 50 percent (%) and not more than 80% of a length of circle perimeter of the second virtual circle C2.

The position of the communication path55and the position of the heater131are measured, for example, by using an X-ray CT (Computed Tomography). If it is only the position of the heater131, it can be measured using, for example, an ultrasonic flaw detector. The position of the communication path55and the position of the heater131are also possible to be observed by a destructive inspection of the cross section or the like based on an electron microscopy such as scanning electron microscopy (SEM).

According to the embodiment, the uncontrollable range of temperature adjustment in the plane of the object to be processed can be limited by equalizing substantially a portion hardest to heat to a portion hardest to cool. In the embodiment, the portion hardest to heat to the portion hardest to cool are close to the through hole57. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed in other region different from the through hole can be improved. Also in the vicinity of the through hole, a region of cool spot hardest to heat is substantially equal to a region of hot spot hardest to cool, and thus equilibrium between heating and cooling is easily achieved, and the uniformity of the temperature distribution in the plane of the object to be processed can be improved.

FIG. 3is a schematic plan view showing a vicinity of the through hole of the embodiment.

FIG. 4is a schematic plan view showing a folded-back portion of the heater of the embodiment.

FIG. 3is a schematic plan view of the electrostatic chuck100as viewed in the direction of the arrow A shown inFIG. 1. In other words,FIG. 3is a schematic plan view of the electrostatic chuck100as viewed in a direction perpendicular to the first major surface11a. It is noted that, in the schematic plan view shown inFIG. 3, the heater131and the communication path55are shown by solid lines instead of broken lines for convenience of description.

As shown inFIG. 3, when viewed in the direction perpendicular to the first major surface11a, a circle approximated by the inner (side of the through hole57) diameter of the communication path55is defined as a first virtual circle C1. Alternatively, as shown inFIG. 2, when viewed in the direction perpendicular to the first major surface11a, a circle passing the portion55aof the communication path55closest to the through hole57and any two portions (inFIG. 3, portion55band portion55c) on the side (inside) of the trough hole57of the communication path55is defined as a first virtual circle C1. At this time, a distance D5between a center55dof the first virtual circle C1and a center131dof the second virtual circle C2is within 0.2 mm. At this time, as shown inFIG. 4, a dimension D6of a portion (round portion) on the outer side (outer circumference) of the folded-back portion131eof the heater131is, for example, about not less than 0.6 mm and approximately not more than 1 mm (not less than R 0.6, not more than R1).

It is preferable that a distance between the center55dof the first virtual circle C1and the center131dof the second virtual circle C2is 0 mm. That is, it is preferable that the center55dof the first virtual circle C1overlaps the center131dof the second virtual circle C2.

FIG. 5is a schematic plan view showing a vicinity of one other through hole of the embodiment.

FIG. 5is a schematic plan view of the electrostatic chuck100as viewed in the direction of the arrow A shown inFIG. 1similar toFIG. 2andFIG. 3.

An arrangement pattern of the heater131in the vicinity of the through hole57shownFIG. 5is different from an arrangement pattern of the heater131in the vicinity of the through hole57shown inFIG. 2andFIG. 3. In the vicinity of the through hole57shown inFIG. 2andFIG. 3, the upper side heater is continuous. On the other hand, In the vicinity of the through hole57shown inFIG. 5, the upper side heater is not continuous. In any example shown inFIG. 2,FIG. 3andFIG. 5, when viewed in the direction perpendicular to the first major surface11a, the arrangement pattern of the heater131is bilaterally symmetric about an arbitrary straight line57bpassing the center axis57aof the through hole57. In the case where the through hole57is a lift pin hole, it is relatively frequent that the arrangement pattern of the heater131is laterally symmetric as seen from the arbitrary straight line57bpassing the center axis57aof the through hole57.

As shown inFIG. 5, even in the case of the arrangement pattern of the heater131, when viewed in the direction perpendicular to the first major surface11a, at least a part of the heater131exists on a side of the through hole57as viewed from a portion55aof the communication path55closest to the through hole57. A length of the portion (inFIG. 5, circular arc CA1, circular arc CA2and circular arc CA3) where the second virtual circle C2crosses the heater131is not less than 50 percent (%) and not more than 80% of a length of circle perimeter of the second virtual circle C2. The distance D1, the distance D2, the width D3, the width D4, the distance D5and the dimension D6are as described above with respect toFIG. 2andFIG. 3.

FIG. 6AandFIG. 6Bare schematic views showing the vicinity of the one other through holes of the embodiment.FIG. 6AandFIG. 6Bare schematic plan views of the electrostatic chuck100as viewed in the direction of the arrow A shown inFIG. 1similar toFIG. 2andFIG. 3.

A curvature of a planar shape of the upper side heater131inFIG. 6Ais larger than a curvature of a planar shape of the upper side heater131in the vicinity of the through hole57shown inFIG. 2andFIG. 3. InFIG. 6A, a part of the upper side heater131overlaps a part of the communication path55in the Z-direction in the vicinity of the through hole57. InFIG. 6B, the heater131is configured from the pattern extending linearly along the X-Y plane. Also in examples shown inFIG. 6AandFIG. 6B, the distance D1, the distance D2, the width D3, the width D4, and the distance D5are as described above with respect toFIG. 2andFIG. 3. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved.

FIG. 7AandFIG. 7Bare schematic views showing the vicinity of the one other through holes of the embodiment.FIG. 7AandFIG. 7Bare schematic plan views of the electrostatic chuck100as viewed in the direction of the arrow A shown inFIG. 1similar toFIG. 2andFIG. 3.

Examples shown inFIG. 7AandFIG. 7Bare different from examples shown inFIG. 2andFIG. 3in the arrangement pattern of the communication path55. In the examples ofFIG. 7AandFIG. 7B, the communication path55branches into a main flow path551and a sub flow path552in the vicinity of the through hole57. As shown inFIG. 7A, a width D8aof the sub flow path552is narrower than the width D3of the main flow path551. As shown inFIG. 7B, a width D8bof the sub flow path552is narrower than the width D3of the main flow path551. The width of the flow path is a length of the flow path along the direction perpendicular to a direction along which the cooling medium flows into when viewed in the direction perpendicular to the first major surface11a.

In the specification of the application, when the communication path55branches off in this manner, “the portion55aof the communication path55closest to the through hole57” is referred to as “the portion of the main flow path551closest to the through hole57”. In such a case, also in the examples shown inFIG. 7AandFIG. 7B, the distance D1, the distance D2the width D3, the width D4and the distance D5are as described above with respect toFIG. 2andFIG. 3.

FIG. 8is a graph chart illustrating an example of the relationship between a ratio of a circumference and a lowering rate of the temperature.

The horizontal axis of the graph chart shown inFIG. 8represents a ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2(the length of the portion where the second virtual circle C2crosses the heater131/the length of the circular perimeter of the second virtual circle C2(%)). The vertical axis of the graph chart shown inFIG. 8represents the lowering rate of the temperature to the average temperature (%).

As shown inFIG. 8, if the ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2is high, the lowering rate of the temperature to the average temperature is low. The lowering rate of the temperature to the average temperature is favorable to be not more than 10%. If the lowering rate of the temperature to the average temperature is higher than 10%, it becomes difficult to heat adequately the region in the vicinity of the through hole57.

That is, in the case where the ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2is less than 50%, the heater131in the vicinity of the through hole57is deficient. Thereby, it becomes difficult to heat adequately the region in the vicinity of the through hole57. In other words, the region in the vicinity of the through57may be the cool spot.

On the other hand, in the case where the ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2is higher than 80%, the heater131in the vicinity of the through hole57is excessive. Therefore, there is a fear that an insulation distance between the heaters131cannot be secured.

According to this, the ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2is favorable to be not less than 50% and not more than 80%.

The ratio between the length of the portion where the second virtual circle C2crosses the heater131and the length of the circular perimeter of the second virtual circle C2is preferable to be not less than 70% and not more than 80%. In such a case, relatively many heaters131can be provided in the vicinity of the through hole57while securing the insulation distance between the heaters131.

FIG. 9is a graph chart illustrating an example of the relationship between a temperature fluctuation and a heater area ratio.

The horizontal axis of the graph chart shown inFIG. 9represents a heater area ratio (%). The heater area ratio is a ratio of the area of the heater131to the area of the ceramic dielectric substrate11, when viewed in the direction perpendicular to the first major surface11a.

The left vertical axis ofFIG. 9represents the temperature fluctuation ΔT (° C.) of the object to be processed W (for example, wafer) placed on the electrostatic chuck and having the temperature controlled. The temperature fluctuation ΔT is a temperature difference between the highest temperature position and the lowest temperature position.

The right vertical axis ofFIG. 9represents a ratio Rt (%) of the temperature fluctuation from the reference of the object to be processed W. For example, in the case where the temperature of the object to be processed W is changed from the temperature T1to the temperature T2by the electrostatic chuck, ratio Rt (%)=(temperature fluctuation ΔT)/(temperature T2−temperature T1)×100 is represented.

InFIG. 9, in the electrostatic chuck described with reference toFIG. 1, the heater area ratio can be changed by changing the width of the heater131or arranging the heater131densely. As shown inFIG. 9, in the case where the heater area ratio is not more than 20%, the temperature fluctuation ΔT is not less than 5° C., the ratio Rt Is not less than 10%. If the heater area ratio is further decreased, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because of difficulty of heating the region away from the heater131when the heater131is sparse.

On the other hand, also in the case where the heater area ratio is not less than 80%, the temperature fluctuation ΔT is not less than 5° C., and the ratio Rt is not less than 10%. If the heater area ratio further increases, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because that the region having the heaters131arranged densely is easily heated but the region having the heaters131not arranged remains difficult to be heated. Therefore, the temperature difference is remarkable.

The heater area ratio is limited by a factor other than the temperature fluctuation as well. For example, for securing the insulation distance, the distance of closest approach between the heaters131is desired to be not less than 0.2 mm and not more than 5 mm, and the distance from the heater131to the outer circumference of the ceramic dielectric substrate11is desired to be not less than 0.05 mm and not more than 7 mm. Therefore, the heater area ratio is less than 100%. For example, when the heater area ratio is not less than 90%, the breakdown voltage between the heaters is insufficient, and when the heater area ratio is not less than 85%, the breakdown voltage between the heater outer circumferences is insufficient.

According to the above, in the embodiment, the heater area ratio is desired to be not less than 20% and not more than 80%. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved. The heater area ratio is desired to be not less than 40% and not more than 60%. Thereby, the temperature fluctuation ΔT can be not more than 2° C. and the ratio Rt can be not more than 4%.

FIG. 10is a graph chart illustrating an example of the relationship between the temperature fluctuation and the communication path area ratio. The horizontal axis represents the communication path area ratio (%). The communication path area ratio is a ratio of the communication path55to the area of the ceramic dielectric substrate11, when viewed in the direction perpendicular to the first major surface11a.

The left vertical axis ofFIG. 10represents the temperature fluctuation ΔT (° C.) similar to the left vertical axis ofFIG. 9. The right vertical axis ofFIG. 10represents the ratio Rt (%) of the temperature fluctuation from the reference similar to the right vertical axis ofFIG. 9.

InFIG. 10, in the electrostatic chuck described with reference toFIG. 1, the communication path area ratio can be changed by changing the width of the communication path55or arranging the communication path55densely. In this example, the cooling medium is caused to pass through the communication path55.

As shown inFIG. 10, when the communication path area ratio is not more than 20%, the temperature fluctuation ΔT is not less than 5° C., and the ratio Rt is not less than 10%. If the communication path area ratio is further decreased, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because that the region away from the communication path55is easy to be the hot spot when the communication path55is sparse.

On the other hand, also in the case where the communication path area ratio is not less than 80%, the temperature fluctuation ΔT is not less than 5° C., and the ratio Rt is not less than 10%. If the communication path area ratio is further increased, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because that the region having the communication path55arranged densely is easily cooled but the region having the communication path55not arranged remains difficult to be cooled. Therefore, the temperature difference is remarkable.

The communication path area ratio is limited by a factor other than the temperature fluctuation as well. For example, for securing the strength, the distance of closest approach between the communication paths55is desired to be not less than 0.3 mm and not more than 15 mm, and the distance from the communication path55to the outer circumference (outer circumference of upper portion50a) of the base plate50is desired to be not less than 0.3 mm and not more than 10 mm. Therefore, the communication path area ratio is less than 100%.

According to the above, in the embodiment, the communication path area ratio is desired to be not less than 20% and not more than 80%. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved. The communication path area ratio is preferable to be not less than 40% and not more than 60%. Thereby, the temperature fluctuation ΔT can be not more than 2° C. and the ratio Rt can be not more than 4%.

FIG. 11is a graph chart illustrating an example of the relationship between the temperature fluctuation and the ratio of the heater area to the communication path area.

The horizontal axis ofFIG. 11represents a ratio of the heater area to the communication path area. This is calculated by (heater area)/(communication path area) (%). The heater area is an area of the heater131as viewed in the direction perpendicular to the first major surface11a. The communication path area is the area of the communication path55as viewed in the direction perpendicular to the first major surface11a.

The left vertical axis ofFIG. 11represents the temperature fluctuation ΔT (° C.) similar to the left vertical axis ofFIG. 9. The right vertical axis ofFIG. 11represents the ratio Rt (%) of the temperature fluctuation from the reference similar to the right vertical axis ofFIG. 9.

InFIG. 11, in the electrostatic chuck described with reference toFIG. 1, a ratio of the heater area to the communication path area can be changed by changing the width of the heater131and the width of the communication path55or arranging the heater131and the communication path55densely. Here, the minimum value of the width of the heater is 0.5 mm, and the minimum value of the width of the communication path55is 1 mm. In this example, the cooling medium is caused to pass through the communication path55. The temperature of the object to be processed W is controlled by heating by the heater131while flowing the cooling medium into the communication path55.

As shown inFIG. 11, when the ratio of the heater area to the communication path area is not more than 60%, the temperature fluctuation ΔT is not less than 5° C., and the ratio Rt is not less than 10%. If the ratio of the heater area to the communication path area is further decreased, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because that the density of the communication path55to the heater131is high, and the cool spot occurs easily.

On the other hand, also in the case where the ratio of the heater area to the communication path area is not less than 180%, the temperature fluctuation ΔT is not less than 5° C., and the ratio Rt is not less than 10%. If the ratio of the heater area to the communication path area is further increased, the temperature fluctuation ΔT and the ratio Rt increase steeply. This is considered to be because that the density of the heater131to the communication path55is high, and the hot spot occurs easily.

According to the above, in the embodiment, it is desired that both of the heater131and the communication path55arranged with an adequate density. The ratio of the heater area to the communication path area is desired to be not less than 60% and not more than 180%. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved. The ratio of the heater area to the communication path area is preferable to be not less than 100% and not more than 140%. Thereby, the temperature fluctuation ΔT can be not more than 2° C. and the ratio Rt can be not more than 4%.

It is noted that the heater area ratio inFIG. 9, the communication path area ratio inFIG. 10, and the ratio of the heater area to the communication path area inFIG. 11may be calculated with respect to the whole adhesion surface of the electrostatic chuck100, respectively, may be calculated with respect to the range surrounded by the outer circumference of the electrostatic chuck100, and may be calculated in the range of approximately 50 mm×50 mm of the electrostatic chuck100. The average value of calculated values from the multiple (approximately three) ranges of 50 mm×50 mm may be used, respectively for the heater area ratio, the communication path area ratio, and the ratio of the heater area to the communication path area.

FIG. 12AandFIG. 12Bare schematic plan views showing a folded-back portion of the heater.

FIG. 13AandFIG. 13Bare schematic enlarged views enlarging the folded-back portion of the heater.

FIG. 12Ais the schematic plan view showing the folded-back portion of the heater of the embodiment.FIG. 12Bis the schematic plan view showing the folded-back portion of the heater of a comparative example.FIG. 13Ais the schematic enlarged view enlarging a region AR1shown inFIG. 12A.FIG. 13Bis the schematic enlarged view enlarging a region AR2shown inFIG. 12B.

FIG. 12Ashows a state of close folded-back portions131eof multiple heaters131. The folded-back portions131eof the heaters131are portions bent from a first direction to a second direction different from the first direction.FIG. 12Bshows a state of close folded-back portions134eof multiple heaters134. The folded-back portions134eof the heaters134are portions bent from a third direction to a fourth direction different from the third direction. In an arrangement pattern of the heaters131shown inFIG. 12A, a first heater135is close to a second heater136. In an arrangement pattern of the heaters134, a first heater137is close to a second heater138.

If an area of a space portion141between the folded-back portion131e(first folded-back portion) of the first heater135and the folded-back portion131e(second folded-back portion) of the second heater136is broad, the temperature controllability of the object to be processed W is lowered, and thus the uniformity of the temperature distribution in the plane of the object to be processed W may be difficult to be improved. Contrarily, when the area of the space portion141the folded-back portion131eof the first heater135and the folded-back portion131eof the second heater136is adequate, the temperature controllability of the object to be processed W can be improved, and the uniformity of the temperature distribution in the plane of the object to be processed W can be improved.

Here, as shown inFIG. 13A, in the embodiment, a distance of closest approach between the first heater135and the second heater135is denoted as “D11”. A distance between a round end portion131fof the folded-back portion131eof the first heater135and a round end portion131fof the folded-back portion131eof the second heater136is denoted as “D12”.

In the specification, “round end portion” refers to the intersection of the round portion and the linear portion.

As shown inFIG. 13B, in the comparative example, a distance of closest approach between the first heater137and the second heater138is denoted as “D13”. A distance between a round end portion134fof the folded-back portion134eof the first heater137and a round end portion134fof the folded-back portion134eof the second heater138is denoted as “D14”.

At this time, in the embodiment, a ratio (D11/D12) of the distance of closest approach D11to the distance D12between the round end portions131fis not less than 50% and less than 100%. In other words, the distance of closest approach D11is not less than 50% and less than 100% of the distance D12between the round end portions131f.

Contrarily, in the comparative example, a ratio (D13/D14) of the distance of closest approach D13to the distance D14between the round end portions134fis less than 50%. In other words, the distance of closest approach D13is less than 50% of the distance D14between the round end portions134f.

According to the embodiment, the distance of closest approach between the multiple heaters131is defined in order to define a density of the space portion141in the portion of the closest folded-back portions131eof the multiple heaters131, and thus the temperature controllability of the object to be processed W can be improved and the uniformity of the temperature distribution of the object to be processed W can be improved.

The ratio of the distance of closest approach to the distance between the round end portions will be further described with reference to drawings.

FIG. 14is a graph chart illustrating an example of the relationship between a ratio of a distance of closest approach to a distance between round end portions and temperature difference in the plane of the object to be processed.

FIG. 15is a table illustrating an example of the relationship between a ratio of a distance of closest approach to a distance between round end portions and temperature difference in the plane of the object to be processed.

FIG. 16AtoFIG. 16Eare schematic views illustrating an example of the temperature distribution in the plane of the object to be processed.

The inventors have investigated the relationship between a ratio of the distance of closest approach to the distance between round end portions (the distance of closest approach/the distance between the round end portions) and temperature difference in the plane of the object to be processed. As shown inFIG. 15, the inventors have investigated the temperature difference in the plane of the object to be processed W about the cases where the ratio of the distance of closest approach to the distance between round end portions is 22% (Case 1), 26% (Case 2), 33% (Case 3), 50% (Case 4), 67% (Case 5) and 80% (Case 6).

One example of results of the investigation is as shown inFIG. 14toFIG. 16E. That is, as shown inFIG. 14andFIG. 14, if the ratio of the distance of closest approach to the distance between the round end portions is higher, the temperature difference in the plane of the object to be processed W is lowered. In the case where the temperature difference in the plane of the object to be processed W is set to be not more than 1° C., the ratio of the distance of closest approach to the distance between the round end portions is necessary to be not less than 50% and less than 100%. As shown inFIG. 16AtoFIG. 16E, in the case where the ratio of the distance of closest approach to the distance between the round end portions is not less than 50% and less than 100%, lowering of the temperature in the space portion141between the folded-back portion131eof the first heater135and the folded-back portion131eof the second heater136is suppressed.

FIG. 17AandFIG. 17Bare schematic views illustrating one other electrostatic chuck according to the embodiment.

FIG. 17Ais a schematic cross-sectional view of an electrostatic chuck101according to the embodiment.FIG. 17Bcorresponds to a schematic cross-sectional view enlarging a part of the cross section shown inFIG. 1.

The electrostatic chuck101illustrated inFIG. 17Aincludes a bypass electrode139. Other than this, the similar description about the electrostatic chuck100described inFIG. 1can be applied to the electrostatic chuck101. The example shown inFIG. 17Ais about the heater plate structure, but the heater or the bypass electrode may be included in ceramic, and the structure and the manufacturing method are not limited.

The bypass electrode139is provided between the base plate50and the electrode layer12in the Z-direction. In this example, the bypass electrode139is located between the base plate50and the heater131in the Z-direction. However, the position of the bypass electrode139is not limited thereto. For example, the bypass electrode139may be located between the electrode layer12and the heater131in the Z-direction.

Materials for the bypass electrode include, for example, a metal including at least one of stainless steel, titanium, chromium, nickel, copper or aluminum. The bypass electrode139is electrically connected to the heater131. The bypass electrode139is electrically connected to an terminal62. The heater current133(seeFIG. 1) can be flown through the terminal62and the bypass electrode139. By providing the bypass electrode139like this, the freedom of arrangement of the terminal62and the heater131can be higher. The heater131does not contact directly the terminal52, and thus the heater131can be suppressed from damage.

FIG. 17Bis a schematic plan view illustrating the bypass electrode of the embodiment.

As shown inFIG. 17B, the electrostatic chuck101is provided with the multiple bypass electrodes139. When viewed in the direction perpendicular to the first major surface11a, it is desired that the first major surface11ais substantially circular, and the multiple bypass electrodes139overlaps substantially the whole of the first major surface11a. In this example, eight bypass electrodes139are provided. The planar shape of each of the bypass electrodes139is, for example, substantially fan-shaped. This fan shape is surrounded by the arc along the outer circumference of the first major surface11aand two radiuses of the arc. However, for example, the bypass electrode may be substantially comb-shaped and may be substantially circular, and the shape of the bypass electrode is not limited thereto.

The electrostatic chuck101has a gap G1. The gap G1is a region between mutually adjacent two bypass electrodes139(for example, first bypass electrode139a, and a second bypass electrode139b). The in-plane uniformity of the current supplied to the heater131, for example, can be improved by providing the multiple bypass electrodes139so as to divide the circle.

FIG. 18is a graph chart illustrating an example of the relationship between the temperature fluctuation and a gap width of a bypass electrode.

The horizontal axis ofFIG. 18represents a gap width D15of the bypass electrode139. The gap width D15is a width of the gap G1shown inFIG. 17B. In other words, the gao width D15is a distance between the mutually adjacent two bypass electrodes in a circumferential direction of the electrostatic chuck101. The left vertical axis ofFIG. 18represents the temperature fluctuation ΔT (° C.) similar to the left vertical axis ofFIG. 9. The right vertical axis ofFIG. 18represents the ratio Rt (%) of the temperature fluctuation from the reference similar to the right vertical axis ofFIG. 9.

FIG. 18illustrates the characteristics of the case where the multiple gap widths D15are changed in the electrostatic chuck101. As shown inFIG. 18, when the gap width D15Is not more than 10 mm, the temperature fluctuation ΔT is not more than 5° C., and the ratio Rt is not more than 10%. This is considered to be because that the gap G1is easy to function like as a heat insulating layer. In the case where the gap width D15is less than 0.05 mm, a breakdown voltage between the bypass electrodes139may be lowered. In the embodiment, the gap width D15is desired to be not less than 0.05 mm and not more than 10 mm. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved. The gap width D15is preferably to be not less than 0.05 mm and not more than 7.5 mm, furthermore preferably to be not less than 0.05 mm and not more than 2.0 mm.

FIG. 19is a graph chart illustrating an example of the relationship between the temperature fluctuation and a gap depth of a bypass electrode.

The horizontal axis ofFIG. 19represents a gap depth D16of the bypass electrode139. The gap depth D16is a depth of the gap G1(a length along the direction perpendicular to the first major surface11a) shown inFIG. 17A. In other words, the gap depth D16corresponds to a thickness of the bypass electrode139. The left vertical axis ofFIG. 19represents the temperature fluctuation ΔT (° C.) similar to the left vertical axis ofFIG. 9. The right vertical axis ofFIG. 19represents the ratio Rt (%) of the temperature fluctuation from the reference similar to the right vertical axis ofFIG. 9.

FIG. 19illustrates the characteristics of the case where the gap depth D16is changed. As shown inFIG. 19, when the gap depth D16is not more than 1 mm, the temperature fluctuation ΔT is not more than 5° C., the ratio Rt is not more than 10%. In the embodiment, the gap depth D16is desired to be not less than 0.01 mm and not more than 1 mm. Thereby, the uniformity of the temperature distribution in the plane of the object to be processed can be improved. The gap depth D16is preferably not less than 0.01 mm and not more than 0.8 mm, furthermore preferably not less than 0.01 mm and not more than 0.4 mm.

FIG. 20is a schematic cross-sectional view illustrating a wafer processing apparatus according to one other embodiment of the invention.

A wafer processing apparatus500according to the embodiment includes a processing chamber501, an upper electrode510, and the electrostatic chuck (for example, electrostatic chuck100) previously described with reference toFIG. 1toFIG. 9. A ceiling of the processing chamber includes a processing gas introduction port502for introducing the processing gas into the inside. A bottom plate of the processing chamber501includes an exhaust port503for reducing a pressure to exhaust the inside. A high frequency power supply504is connected to the upper electrode510and the electrostatic chuck100, and a pair of electrodes including the upper electrode510and the electrostatic chuck10is configured to oppose in parallel to be separated from each other with a prescribed spacing.

In the wafer processing apparatus500according to the embodiment, if a high frequency voltage is applied between the upper electrode510and the electrostatic chuck10, high frequency discharge is generated, the processing gas introduced into the processing chamber501is excited and activated by a plasma, and the object to be processed W is subjected to be processed. The object to be processed W may include a semiconductor substrate (wafer). However, the object to be processed W Is not limited to the semiconductor substrate (wafer), and, for example, may be a glass substrate used for a liquid crystal display device.

The high frequency power supply504is electrically connected to the base plate50of the electrostatic chuck100. The base plate50includes a metal material such as aluminum or the like as described previously. That is, the base plate50is conductive. Thereby, the high frequency voltage is applied between the upper electrode510and the base plate50.

A apparatus having the configuration like the wafer processing apparatus500is called generally a parallel plate type RIE (Reactive Ion Etching) apparatus, however the electrostatic chuck100according to the embodiment is not limited to application to this device. For example, it can be broadly applied to a so called pressure reduction processing apparatus such as an ECR (Electron Cyclotron Resonance) etching apparatus, an inductively coupled plasma processing apparatus, a helicon wave plasma processing apparatus, a plasma separation type plasma processing apparatus, a surface wave plasma processing apparatus, and a plasma CVD (Chemical Vapor Deposition) apparatus. The electrostatic chuck100according to the embodiment can be applied broadly to a substrate processing apparatus which the processing and inspection are performed under atmospheric pressure like an exposure device and an inspection device as well. However, considering high plasma resistance of the electrostatic chuck100according to the embodiment, the electrostatic chuck100is favorable to be applied to the plasma processing apparatus. Among the configuration of these apparatus, the public known configuration can be applied to parts other than the electrostatic chuck100according to the embodiment, and thus the description will be omitted.

Hereinabove, exemplary embodiments of the invention are described with reference to specific examples. However, the embodiments of the invention are not limited to these specific examples. The exemplary embodiments described above can be modified appropriately by a person skilled in the art, and such modifications are also encompassed within the scope of the invention to the extent that the purport of the invention is included. For example, shapes, dimensions, materials, and arrangement of the respective components included the electrostatic chuck100, the electrostatic chuck substrate110and the baseplate50, and the placement of the heater131and the through hole57are not limited to the illustrated and can be modified appropriately.

The respective components included in the embodiments described above can be combined within the extent of technical feasibility and are included in the scope of the invention to the extent that the spirit of the invention is included.

INDUSTRIAL APPLICABILITY

According to one embodiment of the invention, an electrostatic chuck and a wafer processing apparatus capable of improving uniformity of the temperature distribution in a plane of an object to be processed are provided.

EXPLANATION OF LETTERS OR NUMERALS