TW201603164A - Heated electrostatic chuck - Google Patents

Abstract

Heated electrostatic chucks are provided that can improve uniformity of heating of a substrate on the electrostatic chucks, and can improve thermal performance of an electrostatic chuck relative to other thermal performance goals. One electrostatic chuck includes a ceramic structural element having a sidewall surface on an outer perimeter of the electrostatic chuck, and at least one sidewall heater element disposed on or within at least a portion of the sidewall surface.

Description

Heating electrostatic chuck [related application]

The present application claims the benefit of U.S. Provisional Application No. 61/973,787, filed on Apr. 1, 2014, the entire disclosure of which is incorporated herein by reference.

The invention generally relates to electrostatic chucks having at least one heater. In one version, the electrostatic chuck includes a ceramic structural member having a sidewall surface on an outer periphery of the electrostatic chuck, and at least one sidewall heater member disposed on or in at least a portion of the sidewall surface.

Electrostatic chucks (ESCs) are often used in the semiconductor manufacturing industry for plasma-based or vacuum-based semiconductor processes such as ion implantation, etching, chemical vapor deposition (CVD), and others. During the semiconductor process, the workpiece or substrate is clamped in a fixed position on the support surface.

The electrostatic clamping capabilities of these ESCs and workpiece temperature control have proven to be quite valuable in processing semiconductor substrates, workpieces or wafers, such as germanium wafers. See, for example, U.S. Patent No. 8,517,392 B2 to Hida et al.

Existing electrostatic chucks used in processes such as ion implantation are beveled to avoid implanting a beam hitting chuck during an angled ion beam implantation. Attributable to this bevel, it is difficult to reach the wafer Uniform heating, because the heater has a diameter smaller than the diameter of the wafer.

Therefore, there is a need for an improved chuck design that improves the uniformity of heating of the wafer. In addition, there is a need for improved chuck designs that improve performance relative to other thermal targets.

According to a version of the present invention, there is provided an electrostatic chuck comprising: a ceramic structural member having a sidewall surface on an outer periphery of one of the electrostatic chucks; and at least one sidewall heater member, the at least one sidewall heater The component is disposed on or in at least a portion of the sidewall surface.

In further related versions, the at least one sidewall heater element can be disposed on the at least a portion of the sidewall surface or can be embedded beneath the at least a portion of the sidewall surface. The electrostatic chuck can further include a back heater element disposed on an opposite side of one of the electrostatic chucks relative to one of the clamping surfaces of the electrostatic chuck.

In other related versions, the at least one sidewall heater element can include a heater wire. The heater wire may be mechanically retained (eg, by being located in one of the recesses in the at least a portion of the sidewall surface) on the at least a portion of the sidewall surface; or may be below the at least a portion of the sidewall surface Embed. The heater wire may comprise at least one metal selected from the group consisting of aluminum, copper, titanium, molybdenum, silver, platinum, gold, nickel, tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese and mixtures, oxides and nitrides. The heater wire can, for example, comprise a nickel-chromium alloy (NiCr) heater wire or a silver (Ag) heater wire.

In other related versions, the at least one sidewall heater element can comprise a heater element film. The heater element film may include at least one selected from the group consisting of A metal: aluminum, copper, titanium, molybdenum, silver, platinum, gold, nickel, tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese, and mixtures thereof, oxides and nitrides. For example, the heater element film may comprise a nickel-chromium alloy (NiCr) film. The heater element film can have a film thickness of less than about 100 [mu]m (such as a film thickness in the range between about 1 [mu]m and about 10 [mu]m), or a film thickness of less than about 1 [mu]m. The heater element film may comprise an electrically insulating and mechanically stable layer of one or more of the following: glass, alumina, ceramic, metal oxide, transition metal oxide, rare earth oxide, metal nitrogen Compounds, transition metal nitrides, rare earth nitrides, metal oxynitrides, cerium oxide, cerium nitride, and cerium oxynitride.

In other related versions, the ceramic structural component can include at least one of aluminum oxide (Al ₂ O ₃ ), aluminum nitride, and tantalum nitride; and can have a cylindrical shape, or can include a beveled sidewall surface. The at least one sidewall heater element can provide a maximum power of between about 100 watts and about 2000 watts.

In other related versions, the electrostatic chuck can further include a heater control circuit. The at least one sidewall heater element can comprise a single sidewall heater strip, and the heater control circuit can be electrically connected to control operation of the single sidewall heater strip; or the at least one sidewall heater element can comprise a plurality of sidewalls A heater strip, and the heater control circuit is electrically connectable to control operation of each of the plurality of sidewall heater strips. The electrostatic chuck can further include a back heater element disposed on an opposite side of one of the electrostatic chucks relative to one of the clamping surfaces of the electrostatic chuck. The heater control circuit can be electrically coupled to control operation of the at least one sidewall heater element and the back heater element to act as a single heater strip of the electrostatic chuck. The at least one sidewall heater element can include one or more sidewall heater strips, and the back heater element can include one or more back heater strips, and the heater control The circuitry can be electrically connected to control operation of each of the one or more sidewall heater strips and the one or more back heater strips. The heater control circuit can be electrically coupled to collectively control operation of at least a portion of the at least one sidewall heater element and at least a portion of the backside heater element as part of at least one common heater band, and in addition to the at least one common In addition to the heater strip, at least one of the at least one sidewall heater element and the backside heater element can comprise another heater strip. The sidewall heater element can provide a varying heating power density across the at least a portion of the sidewall surface.

In another version according to the present invention, there is provided an electrostatic chuck comprising: a ceramic structural member having a sidewall surface; and at least one side heat shield separated from the sidewall surface by Configuring to provide radiant heat to at least a portion of the sidewall surface. The at least one side heat shield comprises (i) a heat shield radiation surface configured to provide the radiant heat to the at least a portion of the sidewall surface, and (ii) a shield heater element configured to heat the The heat shield radiates the surface. In still other related versions, the electrostatic chuck can further include a back heater element disposed on an opposite side of one of the electrostatic chucks relative to one of the clamping surfaces of the electrostatic chuck.

In another version according to the present invention, there is provided an electrostatic chuck comprising: at least one conductive element; and a surface layer activated by a voltage of one of the at least one conductive element to form a charge to thereby Electrostatically clamping to the electrostatic chuck; the surface layer is heated by activating the surface layer to form the charge to electrostatically clamp the same at least one conductive element used in the substrate.

In other related versions, the at least one electrically conductive element can provide a maximum heating power between about 100 watts and about 2000 watts. The electrostatic chuck may further comprise at least one clamping electric a source supply to supply power to the at least one conductive element to generate a voltage by which the surface layer is activated to form a charge to electrostatically clamp the substrate; and further comprising at least one heater power supply to power the at least one conductive element To heat the surface layer. The at least one clamping power supply can include at least one AC power supply, and the at least one heater power supply can include at least one DC power supply.

The version according to the invention has a number of advantages, such as achieving more uniform heating of the substrate on the electrostatic chuck, and additionally improving the thermal performance of the electrostatic chuck.

100‧‧‧Electrostatic chuck

110‧‧‧Ceramic structural components

111‧‧‧The surface of the ceramic structural component facing the wafer

112‧‧‧ sidewall surface

120‧‧‧Back heater

120a‧‧‧Internal heating belt

120b‧‧‧External heating belt

130‧‧‧Clamped wafer

140‧‧‧Sidewall heater element/heater wire

150‧‧‧ Groove

210‧‧‧Ceramic structural components

220‧‧‧Back heater

240‧‧‧Heater wire/wire coil

310‧‧‧Ceramic structural components

312‧‧‧ sidewall surface

320‧‧‧Back heater

330‧‧‧Clamped wafer

360‧‧‧heater element film

370‧‧‧encapsulated film

410‧‧‧Ceramic structural components

412‧‧‧ sidewall surface

460‧‧‧ heater element film

480‧‧‧ pen

482‧‧‧ Rotatable fixture

510‧‧‧Ceramic structural components

512‧‧‧ sidewall surface

520‧‧‧Back heater

540‧‧‧Embedded sidewall heater elements

610‧‧‧Ceramic structural components

620a‧‧‧Back heater

620b‧‧‧Back heater

620c‧‧‧Back heater

640a‧‧‧ sidewall heater elements

640b‧‧‧ sidewall heater elements

640c‧‧‧ sidewall heater elements

690‧‧‧heater control circuit

691a‧‧‧Temperature Sensor

691b‧‧‧Sensor electrical connection

692a‧‧‧Electrical connection for sidewall heater strips

692b‧‧‧ sidewall heater belt

693a‧‧‧Electrical connection for sidewall heater strips

693b‧‧‧ sidewall heater belt

694a‧‧‧Electrical connection for the back heater belt

694b‧‧‧Back heater belt

695a‧‧‧Electrical connection for the back heater belt

695b‧‧‧Back heater belt

696a‧‧‧Electrical connection for common heater belt

696b‧‧‧Common heater belt

712‧‧‧ sidewall surface

720‧‧‧Back heater

742‧‧‧heat shield

744‧‧‧radiative heat

745‧‧‧reflected infrared radiation

746‧‧‧heat shield

747‧‧‧heat shield radiation surface

748‧‧‧Shield heater elements

814‧‧‧ surface layer

840a‧‧‧Conductive components/electrodes/heater components

840b‧‧‧Conductive components/electrodes/heater components

840c‧‧‧Conductive components/electrodes/heater components

840d‧‧‧Conductive components/electrodes/heater components

840e‧‧‧Conductive components/electrodes/heater components

840f‧‧‧Conductive components/electrodes/heater components

897a‧‧‧Directional (DC) heater power supply

897b‧‧‧Directional (DC) heater power supply

897c‧‧‧Directional (DC) heater power supply

897d‧‧‧DC (DC) heater power supply

897e‧‧‧DC (D) heater power supply

897f‧‧‧DC (DC) heater power supply

898‧‧‧Three-phase AC (AC) clamping power supply

A‧‧‧AC power supply

A-‧‧‧ phase

A+‧‧‧ phase

B‧‧‧AC power supply

B-‧‧‧ phase

B+‧‧‧ phase

C‧‧‧AC power supply

C-‧‧‧ phase

C+‧‧‧ phase

The foregoing is more apparent from the following detailed description of exemplary embodiments of the invention, and the claims The drawings are not necessarily to scale, the details of the embodiments of the invention.

1A is a side elevational view of an electrostatic chuck having sidewall heater elements in accordance with one version of the present invention.

Figure 1B is a bottom plan view of an electrostatic chuck having sidewall heater elements in accordance with one version of the present invention.

2 is a bottom plan view of an electrostatic chuck having a wire coil sidewall heater element in accordance with one version of the present invention.

3 is a side elevational view of an electrostatic chuck having a sidewall heater including a heater element film in accordance with one version of the present invention.

4 is a schematic illustration of a jig for pen writing film sidewall heater elements in accordance with one version of the present invention.

5A and 5B respectively include embedded sidewall heater elements in accordance with versions of the present invention Side view and bottom view of the electrostatic chuck.

Figure 6 is a schematic illustration of an electrostatic chuck including a heater control circuit in accordance with a version of the present invention.

7A is a schematic side view of an electrostatic chuck including a passive reflective heat shield according to the prior art; and FIG. 7B is a schematic side view of an electrostatic chuck including a heat reflective heat shield according to a version of the present invention.

Figure 8 is a schematic illustration of an electrostatic chuck using an electrode that performs dual functions as both a clamping electrode and a heater element in accordance with a version of the present invention.

While the invention will be particularly shown and described with reference to the specific embodiments of the embodiments of the invention, Various changes.

Although a variety of compositions and methods are described, it is to be understood that the invention is not limited to the specific exemplifications, compositions, designs, methods or arrangements described, as such molecules, compositions, designs, methods or schemes may vary. It is also understood that the terms used in the description are only for the purpose of describing the particular embodiments of the invention, and the scope of the invention is intended to be limited only by the scope of the appended claims.

It must also be noted that the singular forms "a" and "the" Thus, for example, reference to "sidewall heater element" refers to one or more sidewall heater elements and their reference to equivalents known to those skilled in the art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Methods and materials similar or equivalent to those described herein can be used in practice Or test the version of the invention. All publications mentioned herein are hereby incorporated by reference in their entirety. Nothing herein is to be construed as an admission that the invention "Optional" or "as appropriate" means that the events or circumstances described below may or may not occur, and that the description includes the circumstances in which the event occurred and the circumstances in which the event did not occur. All numerical values herein may be modified by the term "about", whether or not explicitly indicated. The term "about" generally refers to the range of numbers that are familiar to the skilled artisan as equivalent to the recited values (ie, having the same function or result). In some versions, the term "about" refers to ±10% of the stated value, and in other versions, the term "about" refers to ±2% of the stated value. When the composition and method are described in terms of "comprising" each component or step (which is meant to mean "including but not limited to"), the composition and method may also be "substantially composed of various components." And the composition of steps or "composed of various components and steps", this term should be interpreted as defining a substantially closed group of members.

Following is a description of specific examples of the invention.

1A and 1B are side elevational and bottom views, respectively, of an electrostatic chuck having sidewall heater elements in accordance with one version of the present invention. The electrostatic chuck 100 is generally cylindrically symmetrical and has a ceramic structural member 110, such as having a thickness between about 2 mm and about 15 mm (such as having a thickness between about 4 mm and about 12 mm, or a thickness between about 6 mm and about 10 mm). A ceramic (e.g., alumina or the like) body having an embedded electrode for generating a clamping force (not shown in Figs. 1A and 1B). The ceramic structural component 110 has a sidewall surface 112 on the outer periphery of the electrostatic chuck 100. The sidewall surface 112 has a beveled surface to avoid implanting a beam striking chuck during implantation of the angled ion beam, the bevel being defined by a beveled angle that faces the side of the sidewall surface 112 and the ceramic structural component 110 The internal angle between the surfaces 111 of the wafer 130 is tight. Due to the bevel, the bevel may be in a range between about 30 degrees and about 60 degrees The back corner heater 120 has a smaller angle (such as an angle in a range between about 40 degrees and about 50 degrees, or an angle in a range between 43 degrees and about 47 degrees (such as about 45 degrees)) The diameter of the diameter of the wafer 130 varies by up to about 8 mm. In the chuck of FIG. 1A, the back heater 120 is placed under the ceramic structural component 110, because if the backside heater 120 is placed directly under the wafer 130, the backside heater 120 will interfere with the electrostatic clamping function. Due to the difference in the diameter between the back heater 120 and the wafer 130, it is difficult to achieve temperature uniformity on the wafer 130 even if the back heater 120 has an internal heating strip 120a heated to a given temperature and heated to a higher temperature. The high temperature external heating belt 120b. Even though multiple heating strips are used, since the backside heater 120 does not protrude beyond the edge of the wafer 130, significant temperature roll-off towards the edge of the wafer 130 has been predicted and observed.

To improve temperature uniformity on wafer 130, in one version of the invention shown in Figures 1A and 1B, electrostatic chuck 100 includes sidewall heater elements 140, for example by A top surface of the chuck 100 proximate to the holding wafer 130 surrounds the sidewall surface 112 and is disposed on at least a portion of the sidewall surface 112 of the ceramic structural component 110. In one aspect, the sidewall heater element 140 is a heater wire. The heater wire 140 can be, for example, made of one or more metals such as aluminum, copper, titanium, molybdenum, silver, platinum, gold, nickel, tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese. It is made of a mixture, an oxide and a nitride, such as a nickel-chromium alloy (NiCr) or a silver (Ag) wire. The heater wire 140 is mechanically retained on the sidewall surface 112, which may be by any mechanical means of maintaining the heater wire 140 (including by loading the heater wire 140 into the groove, or by using a suitable adhesive, This is achieved by encapsulating the film, clips or other mechanical retention techniques. The heater wire 140 can be engraved, for example, into the recess 150 in the ceramic structural component 110 proximate to the top of the ceramic structural component 110 (such as about 8 mm from the top of the ceramic structural component 110). In some versions, the wire 140 can be closer to the top of the ceramic structural element 110 to modify the heater strip. The wire 140 may extend only over a portion of the sidewall surface 112 or around the entire perimeter of the sidewall surface 112. The thermal expansion of the wires and ceramic structural components when heated can be matched as closely as possible. In one embodiment, the groove 150 may be a suitable material (such as, Ceramabond ^TM 569 sold by New York Valley Cottage, Aremco Products (Aremco Products, Inc.of Valley Cottage, NY, USA) ) is filled, Ceramabond ^TM 569 An embodiment of a temperature stabilized ceramic cement having the same temperature expansion as alumina, and thus the material can cause minimal wear and tear when the ceramic structural element 110 is made of alumina. It should be understood that other materials may be used. The following Example 1 illustrates the calculation of the wire size required to achieve a temperature of, for example, about 650 ° C under certain assumptions, and also illustrates the calculation of the expansion of the wire and ceramic structural elements.

In other versions, the sidewall heater element 140 can be made from a plurality of wire loops, a continuous wire loop, or a wire coil 240 wound around the periphery of the ceramic structural component 210 (here shown as a back heater 220 from the bottom), As shown in the version of Figure 2.

A possible disadvantage of using a heater element in communication with the heated substrate is that poor matching of the thermal expansion coefficient (CTE) of the heater material to the substrate can result in loss of mechanical contact and gaps in heat transfer from the heater to the substrate. In accordance with versions of the present invention, such defects can be addressed by, for example, depositing a film that acts as a sidewall heater element using thin film techniques, as will be explained below with respect to FIG. Thin film technology generally provides intimate contact between the deposited film and the substrate. All methods known for thin film deposition (and other methods of applying a film, including thick film technology) may themselves be suitable for use in versions of the invention, such as: sputter deposition, evaporation, atomic layer deposition, chemical vapor deposition. Cathodic arc gasification, laser ablation, pen writing, shifting Printing, screen printing, manual deposition and impregnation by pen or brush.

3 is a side elevational view of an electrostatic chuck having a sidewall heater including a heater element film in accordance with one version of the present invention. The electrostatic chuck includes a heater element film 360, a ceramic structural element 310, a sidewall surface 312, a backside heater 320, and a clamped wafer 330, and may include an encapsulation film 370. The heater element film 360 can be applied to the sidewall surface 312, having a film thickness in the range of less than about 100 [mu]m (such as a film thickness in the range between about 1 [mu]m and about 10 [mu]m) or a film thickness of less than about 1 [mu]m. The heater element film 360 can, for example, substantially or completely surround the perimeter of the sidewall surface 312 of the electrostatic chuck and can extend along a full height of the sidewall surface 312 or along only a portion of the height of the sidewall surface 312. Additionally, the heater element film 360 can vary in pattern, thickness, height, and other geometrical aspects around different portions of the sidewall surface 312. Additionally, heater element film 360 may extend only over a portion of sidewall surface 312. The heater element film 360 may be made of one or more metals such as aluminum, copper, titanium, molybdenum, silver, platinum, gold, nickel, tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese, and mixtures thereof, The oxide and nitride are made; in one embodiment, the heater element film 360 is made of Nichrome (NiCr). In some versions, the heater element film 360 can be encapsulated by an encapsulating film 370 that is an electrically insulating and mechanically stable layer comprising one or more of the following: glass, alumina, ceramic, metal Oxides, transition metal oxides, rare earth oxides, metal nitrides, transition metal nitrides, rare earth nitrides, metal oxynitrides, cerium oxide, cerium nitride, and cerium oxynitride.

The heater element film 360 of FIG. 3 can be, for example, by sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), printing (eg, pad printing), pen writing, Screen printing, followed by etched plasma deposition, followed by mechanically patterned plasma deposition, followed by patterned electrodeposition, laser deposition, electroplating or subsequent patterning Applied by Atomic Layer Deposition (ALD). For example, sputtering or CVD deposition of heater element film 360 can be accomplished by masking uncovered regions and depositing a heater element film. Alternatively, sputtering or CVD deposition of heater element film 360 may be by material removal, by deposition of heater element film material, masking, followed by chemical etching, bead blasting, or reactive plasma etching Implemented without the need for materials. In accordance with a version of the present invention, an example technique for achieving heater element film 360 using a sputtering technique is outlined below in Example 2. In accordance with a version of the present invention, the following embodiment 3 provides an example of a process for depositing a thin film, in particular, a sputtering process for depositing NiCr. It should be understood that other types of membranes can be used.

In another version according to the present invention, the heater element film 360 may use atomic layer deposition (ALD) (for example, using the electrostatic chuck and its manufacturing method (Electrostatic Chuck and Method) filed on February 6, 2015. Any of the techniques and ALD deposited films taught in PCT Application No. PCT/US2015/014810, the entire disclosure of which is incorporated herein by reference.

Another method of depositing a heater element film in accordance with a version of the present invention is by pen writing. 4 is a schematic illustration of a jig for writing a heater element film in accordance with one version of the present invention. As shown in FIG. 4, in one aspect, the pen 480 writes the heater element film 460 on the sidewall surface 412. The ceramic structural element 410 is mounted on the rotatable clamp 482 at an angle such that the sidewall surface 412 is at a level that achieves the gravity feed of the pen 480. After writing to the film with a conductive material mixed with the carrier material, the material is cured to remove the carrier material leaving only the conductive material remaining. The electrically conductive material should match the ceramic structural element 410 in terms of coefficient of thermal expansion.

Yet another method of depositing a heater element film in accordance with a version of the present invention is by pad printing. The technique of the pad printing method taught in U.S. Patent No. 7,116,547 B2 to Seitz et al. The pad printed film can be made, for example, of ruthenium oxide (RUO ₂ ).

According to another version of the invention, the sidewall heater element can be embedded beneath at least a portion of the sidewall surface. 5A and 5B are side and bottom views, respectively, of an electrostatic chuck including embedded sidewall heater elements in accordance with a version of the present invention. The electrostatic chuck includes a ceramic structural component 510, an embedded sidewall heater component 540, a sidewall surface 512, and a backside heater 520. The embedded sidewall heater element 540 can be, for example, in the form of a wire similar to the heater wire 140 of Figures 1A and 1B; or in the form of a heater wire 240 of Figure 2; or a heater similar to Figure 3 The element film 360 is in the form of an embedded film; or in the form of other heater elements as taught herein; wherein the difference is that the embedded heater element 540 is embedded beneath the sidewall surface 512. By embedding the sidewall heater element 540, a large thermal contact between the heater element 540 and the ceramic structural component 510 can be achieved.

According to another version of the invention, the sidewall heater elements will be used in combination with the back heater. This version combines the advantages of excellent temperature uniformity at the center of the electrostatic chuck (which can be achieved by using a back heater) and provides the heating provided by the sidewall heater elements to the edge of the electrostatic chuck. For example, in the versions of FIGS. 5A and 5B, the embedded sidewall heater element 540 can be used in combination with the back heater 520. It should be understood that other sidewall heater elements taught herein may be combined with the backside heaters taught herein.

6 is a schematic illustration of an electrostatic chuck including a heater control circuit 690 in accordance with a version of the present invention. The electrostatic chuck includes a heater control circuit 690, a plurality of sidewall heater elements 640a, 640b, 640c, a plurality of backside heaters 620a, 620b, 620c, at least one temperature sensor 691a having a sensor electrical connection 691b, ceramic Structural element 610 for sidewall heater Electrical connections 692a, 693a of straps 692b, 693b, electrical connections 694a, 695a for back heater strips 694b, 695b, and electrical connections 696a for common heater strip 696b. Although two sidewall heater strips 692b, 693b, two back heater strips 694b, 695b, and one common heater strip 696b are shown, it will be appreciated that a different number of heater strips for each can be used, as follows Further discussed, it includes only one sidewall heater strip, more than one sidewall heater strip, one back heater strip, and/or one or more back heater strips.

In the version of Figure 6, heater control circuit 690 can be used to achieve the best (or at least improved) performance of the electrostatic chuck. This may, for example, involve achieving a temperature distribution on an electrostatic chuck that achieves multiple (sometimes competing) performance goals. One possible performance goal is to achieve as uniform a temperature as possible across the electrostatic chuck. Another possible performance goal is to have some minimum temperature at any point on the electrostatic chuck. A competing potential performance goal is to minimize stress induced by temperature gradients within the electrostatic chuck to avoid breakage. As an example of a way to compete for performance goals, the temperature drop at the edge of the electrostatic chuck can be improved by adding a second strip at the edge of the bottom heater and operating the heater at a higher power density. However, doing so also results in higher circumferential stress in the electrostatic chuck. It should be appreciated that possible performance goals in the versions of the present invention are not limited to the foregoing; and that one or more of the possible performance goals and other performance goals discussed herein may be satisfied performance goals or may be met in accordance with a version of the present invention. For the purpose of improving performance.

In one version of the invention, the desired performance can be achieved by designing the heater pattern such that the power density varies at different portions of the electrostatic chuck to compensate for different effective heating losses in different regions. This can be used with a single heater control circuit 690 having a single heating strip for all of the heaters on the electrostatic chuck. In this case, the common electrical connection 696a can be used to connect all heaters from the heater control circuit 690 to the electrostatic chuck, which can only be packaged A single sidewall heater element (such as 540 of Figures 5A-5B) and a single backside heater 520, or one or more of a sidewall heater and/or a backside heater are included.

In another version according to the invention, a plurality of heater strips are used, which can be, for example, controlled such that power density variations will be adjusted based on temperature and boundary conditions. In particular, in addition to using one or more common heater strips 696b partially on the side walls and partially on the back side of the electrostatic chuck, the options also include: a) having one or more back heater strips 694b, 695b and one or more sidewall heater strips 692b, 693b; b) having one or more back heater strips 694b, 695b and/or one or more sidewall heater strips 692b, 693b. One or more temperature sensors 691a having one or more corresponding sensor electrical connections 691b can be used to provide thermal data for control. In one example, a temperature sensor 691a having a corresponding sensor electrical connection 691b can be used for each heater strip. It should be appreciated that other configurations of temperature sensor 691a can be used.

In one version of the invention, a single heater strip may have a different sidewall heater element (such as 540 of Figures 5A-5B) that characterizes the power density designed to provide optimum performance over a particular desired temperature range. region. According to one version of the invention, the optimum performance may mean the optimum value of the internal stress for a particular application of the desired temperature distribution.

In accordance with another version of the present invention, a plurality of heater strips (such as strips 692b through 696b of Figure 6) can be strategically designed to optimize performance over a wide range of temperatures or in the presence of a variety of varying boundary conditions. In particular, for example, two heater strips can be used, wherein the bottom heater is designed to produce a uniform temperature distribution in the central region of the electrostatic chuck and the second heater strip (which can be partially or completely on the side wall) ) to optimize performance at different temperatures or under different boundary conditions.

In addition, in the version according to the invention, the side wall heater does not necessarily have to be in its function The rate density is uniform, but can be designed to vary in power density to optimize performance, such as by varying geometries on the sidewall surfaces of the electrostatic chuck. This can be achieved by a single strip and multi-belt sidewall heater design.

In accordance with a version of the present invention, heater control circuit 690 can receive thermal data (such as temperature data) from one or more sensors 691a via sensor electrical connection 691b, and can control heater strips 692b-696b based on thermal data. The operation of one or more of the operations, for example, to adjust power density changes or achieve other thermal performance targets based on temperature and boundary conditions. The heater control circuit 690 can control the power delivered via the sidewall heater elements 640a through 640c and the backside heaters 620a through 620c by applying appropriate voltages to the heater strips 692b through 696b. Heater control circuit 690 can, for example, include one or more microprocessors that are specifically programmed to perform this control of the operation of the heater strip.

It should be appreciated that while the versions of the present invention are discussed herein as being capable of optimizing various thermal performance goals associated with performance, such versions may only improve performance associated with one or more of these thermal performance goals.

7A is a schematic side view of an electrostatic chuck including a passive reflective heat shield according to the prior art; and FIG. 7B is a schematic side view of an electrostatic chuck including a heat reflective heat shield according to a version of the present invention. Radiation loss is the primary source of heat loss in the vacuum of the heated chuck. According to the prior art, one concept of maintaining heat at the side walls of the electrostatic chuck is to surround the edge of the heated electrostatic chuck with a heat shield 742 (see Figure 7A) that will carry most of the infrared light emitted from the edge of the chuck. Radiation returns to the edge. The heat radiated outward from the chuck is indicated in Figures 7A and 7B by a darker colored arrow 744 directed away from the chuck. According to the prior art, a very well designed and implemented heat shield can work very well, but is not perfect. The reflectivity is always less than one hundred percent. The heat shield 742 will never reflect all of the heat lost at the edges. This is illustrated in Figure 7A by a lighter colored arrow 745 (indicating reflected infrared radiation) directed toward the chuck. In addition, some portion of the reflected infrared radiation will be lost by the infrared light completely missing the heat shield or by the reflected radiation not being reflected to the edge.

According to one version of the invention, one possibility to compensate for the loss of infrared radiation is to effectively heat the radiation shield (as shown in Figure 7B), which includes at least one heat shield 746 spaced from the sidewall surface 712 of the electrostatic chuck. . The heat shield 746 includes a heat shield radiation surface 747 configured to provide radiant heat to at least a portion of the sidewall surface 712, and a shield heater element 748 configured to effectively heat the heat shield radiation surface 747. The heat radiated from the chuck and heat shield 746 is indicated by the darker colored arrows 744, while the lost infrared radiation is indicated by the lighter shaded arrows 745. In addition to providing reflection, if the heat shield is heated to a suitable temperature, the effectively heated shield 746 also provides net radiant energy to the edge of the electrostatic chuck. Since the heat shield 746 is effectively heated, its main function does not have to be a function of the reflective heat shield. Almost any heated annular structure placed around the edge of the chuck can be used as the heat shield 746. Although the guard heater element 748 of FIG. 7B is drawn on the radially outer side of the heat shield 746 relative to the center of the electrostatic chuck, it will be appreciated that the guard heater element 748 may also be located radially of the heat shield 746. On the inside. The electrostatic chuck of FIG. 7B can further include a back heater 720 that can be used in combination with the heat shield 746.

Figure 8 is a schematic illustration of an electrostatic chuck using an electrode that performs dual functions as both a clamping electrode and a heater element in accordance with a version of the present invention. According to the prior art, one of the reasons why the heater circuit is not deposited at or near the front surface of the electrostatic chuck is that there will be electrical interaction between the electrostatic clamping electrode and the heater element. Therefore, in the prior art, the heater element was placed on the back side of the electrostatic chuck. In contrast, according to Figure 8 The version, the electrode near the front surface of the electrostatic chuck provides the dual function of acting as both the clamping electrode and the heater element. There may be, for example, six conductive elements 840a through 840f that serve as both electrode and heater elements, although it will be appreciated that different numbers and configurations of electrode/heater elements 840a through 840f may be used. Electrode/heater elements 840a through 840f can be implemented, for example, as heater traces for use as heater element films, using any of the materials and deposition techniques taught above.

According to the version of Figure 8, the circuitry for powering the electrode/heater elements 840a through 840f uses a separate set of one or more power supplies that operate independently of each other for the heating function and the electrostatic clamping function. One of the possible circuits is shown in FIG. Here, the six electrode/heater elements 840a through 840f are powered by floating six independent direct current (DC) heater power supplies 897a through 897f. Each of the power supplies 897a through 897f supplies power to one of the six phases indicated as A+, A-, B+, B-, C+, and C-. The phases are driven by a three-phase alternating current (AC) clamping power supply 898 that includes three AC power supplies A, B, and C having a 120 degree phase angle relative to each other. DC power supplies 897a through 897f provide power to use electrode/heater elements 840a through 840f as heaters, while AC power supplies A, B, and C of power supply 898 provide power to bring electrode/heater elements 840a to 840f is used as a clamping electrode. The heater power supplies 897a through 897f and the clamp power supply 898 can operate simultaneously to provide both heat and clamping. The electrostatic chuck includes a surface layer 814 that is activated by a voltage in the electrode/heater elements 840a-840f to form an electrical charge to electrostatically clamp the substrate to the electrostatic chuck; and the surface layer is also passed through the same electrode / heater elements 840a to 840f are heated. The electrode/heater elements 840a through 840f can, for example, provide a maximum heating power between about 100 watts and about 2000 watts.

In general, the sidewall heater elements in the versions of the invention taught herein can provide, for example, 100 watts to 2000 implant chucks operating in the 600 °C temperature range. The maximum heating power of the tile, but a wide range of temperatures can be achieved. For example, in versions according to the present invention, workpiece temperature control can be achieved at temperatures in the range between about 400 ° C and about 1000 ° C. Additionally, in addition to the heating power provided by the sidewall heater elements, the backside heater elements can provide another heating power of up to 1000 watts or even up to 2000 watts. In accordance with a version of the present invention, Example 4 below provides considerations for heater design criteria from the standpoint of electrical requirements.

In accordance with versions of the present invention, the heater elements taught herein can be used with a wide variety of different possible types of chucks (e.g., vacuum chucks, gravity chucks, and electrostatic chucks). In addition, the chuck can be used in a variety of different possible processes, including both implant processes and processes other than implants, such as etching processes.

A version of the invention has been taught herein in which the electrostatic chuck includes a beveled edge. This bevel is used, for example, in an electrostatic chuck for use in an ion implanter such that the sides of the electrostatic chuck are not hit by the ion implantation beam. For cylindrical chucks (i.e., electrostatic chucks having substantially right-angled edges rather than beveled edges), there are heating-related problems associated with chamfering electrostatic chucks, such as having an edge toward the edge of the electrostatic chuck. Low temperature, but to a lesser extent. Accordingly, it should be understood that the version of the invention taught herein can be used in a cylindrical electrostatic chuck as well as in a beveled electrostatic chuck.

This is followed by a collection of embodiments in accordance with versions of the present invention.

Example 1:

Determination of wire radius

In one aspect, the ceramic structural component 110 (see Figure 1A) has a diameter of about 298 mm at the top. For a 45 degree bevel angle, if the groove 150 is 8 mm from the top of the ceramic structural member 110, the diameter of the groove 150 is about 290 mm, and the resulting length of the loop of the wire 140 is about 911.1 mm. The wire size (wire radius or standard size) required to achieve a temperature of about 650 ° C for the resistance in the range between about 5 Ω and about 25 Ω for the NiCr wire is listed in Table 1. Calculate the wire radius r _w using the following formula:

Where ρ is the resistivity of the wire material, typically measured in ohm meters (Ωm), R is the resistance of the wire, typically measured in ohms (Ωm), and l is the length of the wire, typically in the public Ruler (m) to measure.

Wire expansion from 25 ° C to 650 ° C

The expansion of the wire from 25 ° C to 650 ° C can be calculated using the following formula:

Where l ₀ is the initial wire length, typically measured in meters (m), α is the coefficient of thermal expansion of the wire per ° C, and ΔT is the temperature change in ° C.

By comparison, for alumina ceramic structural elements, from 25 ° C to 600 ° C, α = 8.1 × 10 ^-6 1 / ° C, and thus l = 0.9153 m. In one aspect, the depth of the groove can be about 1.2 mm. With the example dimensions used above, the heating strip will increase by about 2.8 mm in radius.

Example 2

According to the version of the invention, the following outlines the use of sputtering techniques to achieve sidewall heaters One method of components:

1. Establish a negative mask over the substrate covering the uncoated area. This mask, in its simplest form, can be a pattern applied to the substrate using the tape. Another example would be a pattern that is transferred from a photomask to a substrate via exposure of the photosensitive material to the mask and removal of unwanted areas.

2. Apply a coating on all areas (masked and unshielded).

3. Remove the mask and remove the unwanted areas from the substrate.

In accordance with a version of the present invention, an alternative method for achieving a sidewall heater element using a sputtering technique is to cover the entire substrate with a heater material and mask the process applied to protect the area of the deposited film forming the heater circuit. The protective mask can be fabricated in a similar manner as outlined above. It will be apparent to those skilled in the art that a variety of different methods, techniques, and patterns can be used to create a mask.

Example 3

As an example of a process for depositing a thin film, a sputtering process for depositing NiCr will be outlined herein in accordance with a version of the present invention. In addition to NiCr, many other materials will be suitable. A sputtered NiCr film can be created in a system having the following features:

1. A low pressure atmosphere can be generated around the workpiece, preferably in the range of 10 ^-6 Torr, with lower pressure being advantageous.

2. The ability to mount one or more pieces of material to be deposited in the chamber, the chamber being electrically capable of being at an electrical potential relative to the chamber ("target"). One of the desired compositions, NiCr, is mounted in its simplest form on an insulating plate that is connected to a suitable power supply. Alternatively, a piece of nickel and a piece of chrome can be used with an unrelated power supply.

3. The ability to backfill the chamber with a suitable gas to create a plasma around the target. The gas is typically argon Gas, but other inert gases and combinations of inert gases and reactive gases can be used.

According to a version of the invention, a typical deposition process for depositing a sputtered NiCr film has the following workflow:

1. Load the substrate into the chamber.

2. Close and evacuate the chamber to remove ambient air and associated contamination. The lower the pressure, the better; the typical pressure is 10 ^-6 Torr.

3. Backfill with appropriate gas. High purity argon is typically used and the backfill pressure is typically from 2 to 10 mTorr.

4. Ignite the plasma around the target that accelerates the positively charged ions of the gas toward the target. This can be achieved by applying a negative voltage of several hundred volts at the target.

5. The accelerated ions will hit the target and the momentum transfer from the impact will cause a portion of the target material to detach from the surface.

6. These detached materials act in the chamber and some of them will land on the substrate to be coated.

7. The substrate is covered with more or less film for a sufficiently long time.

8. After the desired membrane parameters are reached, the system can be vented and the coated substrate removed.

Example 4

Heater design guidelines for electrical requirements

In accordance with a version of the present invention, the sidewall heater design has a maximum power requirement of 100 watts to 2000 watts for implant chucks operating in the range of 600 degrees Celsius. Typical supply voltages will range from 110V to 240V, with operations as low as 12V and up to 600V being feasible. Lower voltages can be due to the high currents necessary to supply sufficient power in most cases. Above 600V can potentially pose a safety issue as many insulators begin to break at this voltage, especially at high temperatures. The heater design criteria can be estimated using the parameters given here.

From the basic power relationship between power, current, voltage and resistance, the following relationship can be derived: P = V . I ; I = V / R ; → P = V ² / R ; → R = V ² / P ;

This leads to the following design limitations:

It is obvious from this design table that the convenient choice for the heater will be for 24V or 115V operation in the lower power range, where the heater resistance is in the range of 5Ω to 130Ω, and for the high power class, the range of 5Ω to 30Ω will be reasonable. The heater must then be designed to achieve this resistance by designing a heater with an appropriate thickness and a square count of the heater traces. (Square counting is a simple method of designing a heater or a resistive circuit by using a "square" design circuit having circuit elements having a sheet resistivity measured in ohms/square. Two squares designed in series with each other have ohms The resistance of the sheet is 2 times the sheet resistivity, and the two squares in parallel have one half of the sheet resistivity). It should also be considered that the resistance of the heater increases with temperature, so the design must ensure that the heater has a sufficiently low resistance at operating temperature to draw sufficient power.

The imaginary heater design layout with a sputtered NiCr film is outlined below.

The resistivity of NiCr is in the range of ρNiCr = 1...1.5.10 ^-6 Ωm. The relationship between the resistance R , the length l of the resistor trace, the film thickness h, and the resistivity ρ is shown in Equation 1. The ratio l/w is defined as a square, symbolized by the square in the equation.

Using Equation 1, an estimate of the reasonable upper and lower limits of the square can be made. The lower limit will be based on a low resistance heater and low thickness, and the upper limit will be based on large resistance and thick layers.

The total length of the heater is approximately the circumference of the chuck c = 2. π. γ=2. π. 150mm=943mm

The thickness of the insulator is 0.3" at an angle of 45 degrees, and the maximum possible width for a uniform heater strip is 10.8 mm. A space is left on the top and bottom, and a 10 mm wide resistor strip with a length of 940 mm will The number of square designs that resulted in 94. Suppose we need 1000 watts of heater power and 115 V operation, the resistance should be 13.2 Ω. The required film thickness can then be calculated from Equation 1.

This film thickness is feasible. With a resistance of about 58 ohms, 240V operation may be preferred. The film thickness will then be

In summary, according to the version of the invention, a NiCr film forming a 10 mm wide strip around a sidewall having a thickness of 1.6 microns would be a suitable sidewall heater.

While the invention has been shown and described with reference to the embodiments The present invention includes all such modifications and variations and is limited only by the scope of the following claims. In addition, although a particular feature or aspect of the invention may be disclosed in relation to only one of several implementations, the feature or aspect may be one or more of other implementations that may be required and advantageous for any given or particular application. Other features or combinations of aspects. In addition, the terms "includes", "having", "has", "with" or variations thereof are used in the context of the embodiments or claims. It is inclusive in a manner similar to the term "comprising". The term "exemplary" is also intended to mean only the examples, rather than the preferred. It should also be appreciated that the features and/or elements described herein are illustrated in particular dimensions and/or relative to each other for the purpose of brevity and ease of understanding, and the actual size and/or orientation may be substantially The difference described in the article.

Although the invention has been described in considerable detail with reference to particular versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the descriptions and versions contained in this specification.

The teachings of all patents, published applications and references cited herein are hereby incorporated by reference in their entirety.

Claims (35)

An electrostatic chuck comprising: a ceramic structural component having a sidewall surface on an outer periphery of one of the electrostatic chucks; and at least one sidewall heater element disposed on the sidewall surface At least part of it is on or inside. The electrostatic chuck of claim 1, wherein the at least one sidewall heater element is disposed on the at least a portion of the sidewall surface. The electrostatic chuck of claim 1, wherein the at least one sidewall heater element is embedded below the at least a portion of the sidewall surface. The electrostatic chuck of any one of the preceding claims, further comprising a back surface disposed on an opposite side of one of the electrostatic chucks relative to a clamping surface of the electrostatic chuck Heater element. The electrostatic chuck of claim 1, wherein the at least one sidewall heater element comprises a heater wire. The electrostatic chuck of claim 5, wherein the heater wire is mechanically retained on at least a portion of the sidewall surface. The electrostatic chuck of claim 6, wherein the heater wire is located in a recess in the at least a portion of the sidewall surface. The electrostatic chuck of claim 5, wherein the heater wire is embedded under the at least a portion of the sidewall surface. The electrostatic chuck of claim 5, wherein the heater wire comprises at least one metal selected from the group consisting of aluminum, copper, titanium, molybdenum, silver, platinum, gold, Nickel, tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese, and mixtures, oxides and nitrides thereof. The electrostatic chuck of claim 9, wherein the heater wire comprises at least one of a nickel-chromium alloy (NiCr) heater wire and a silver (Ag) heater wire. The electrostatic chuck of claim 1, wherein the at least one sidewall heater element comprises a heater element film. The electrostatic chuck of claim 11, wherein the heater element film comprises at least one metal selected from the group consisting of aluminum, copper, titanium, molybdenum, silver, platinum, gold, nickel, Tungsten, chromium, vanadium, niobium, iron, palladium, Kovar and manganese, and mixtures, oxides and nitrides thereof. An electrostatic chuck according to claim 12, wherein the heater element film comprises a nickel-chromium alloy (NiCr) film. The electrostatic chuck of claim 11, wherein the heater element film has a film thickness of less than about 100 μm. An electrostatic chuck according to claim 14 wherein the film thickness is in a range between about 1 μm and about 10 μm. An electrostatic chuck according to claim 14 wherein the film thickness is less than about 1 μm. The electrostatic chuck of claim 11, wherein the heater element film is encapsulated in an electrically insulating and mechanically stable layer comprising one or more of the following: glass, alumina, ceramic, metal oxide Materials, transition metal oxides, rare earth oxides, metal nitrides, transition metal nitrides, rare earth nitrides, metal oxynitrides, cerium oxide, cerium nitride and cerium oxynitride. The electrostatic chuck of claim 1, wherein the ceramic structural component comprises at least one of alumina (Al ₂ O ₃ ), aluminum nitride, and tantalum nitride. The electrostatic chuck of claim 1, wherein the ceramic structural member has a cylindrical shape. The electrostatic chuck of claim 1, wherein the ceramic structural component comprises a beveled sidewall surface. The electrostatic chuck of claim 1, wherein the at least one sidewall heater element provides a maximum power between about 100 watts and about 2000 watts. The electrostatic chuck of claim 1, further comprising a heater control circuit. The electrostatic chuck of claim 22, wherein the at least one sidewall heater element comprises a single sidewall heater strip, and wherein the heater control circuit is electrically coupled to control operation of the single sidewall heater strip. The electrostatic chuck of claim 22, wherein the at least one sidewall heater element comprises a plurality of sidewall heater strips, and wherein the heater control circuit is electrically connected to control each of the plurality of sidewall heater strips The operation of a side wall heater belt. The electrostatic chuck of claim 22, wherein the electrostatic chuck further comprises a back heater element disposed on an opposite side of one of the electrostatic chucks relative to a clamping surface of the electrostatic chuck. The electrostatic chuck of claim 25, wherein the heater control circuit is electrically connected to control operation of the at least one sidewall heater element and the back heater element as a single heater strip of the electrostatic chuck . An electrostatic chuck according to claim 25, wherein the at least one sidewall heater element One or more sidewall heater strips, and wherein the back heater element includes one or more back heater strips, and wherein the heater control circuit is electrically coupled to control the one or more sidewall heater strips and The operation of each of one or more back heater strips. An electrostatic chuck according to claim 25, wherein the heater control circuit is electrically connected to control at least a portion of the at least one sidewall heater element and at least a portion of the back heater element as at least one common A portion of the heater strip, and wherein at least one of the at least one sidewall heater element and the backside heater element includes another heater strip in addition to the at least one common heater strip. The electrostatic chuck of claim 1, wherein the sidewall heater element provides a varying heating power density on the at least a portion of the sidewall surface. An electrostatic chuck comprising: a ceramic structural component having a sidewall surface; and at least one side heat shield spaced from the sidewall surface and configured to provide radiant heat to the sidewall surface At least a portion of the at least one side heat shield comprises (i) a heat shield radiation surface configured to provide the radiant heat to the at least a portion of the sidewall surface, and (ii) a shield heater element configured To heat the heat shield to radiate the surface. The electrostatic chuck of claim 30, further comprising a back heater element disposed on an opposite side of one of the electrostatic chucks relative to a clamping surface of the electrostatic chuck. An electrostatic chuck comprising: at least one conductive element; a surface layer electrically activated by a voltage of one of the at least one conductive element to electrostatically clamp a substrate to the electrostatic chuck; the surface layer is formed by activating the surface layer to form the charge The same at least one conductive element used to electrostatically clamp the substrate is heated. The electrostatic chuck of claim 32, wherein the at least one electrically conductive element provides a maximum heating power between about 100 watts and about 2000 watts. An electrostatic chuck according to claim 32, further comprising at least one clamping power supply for supplying power to the at least one conductive element to generate the anode for activating the surface layer to form the charge to electrostatically clamp the substrate And the electrostatic chuck further includes at least one heater power supply to power the at least one electrically conductive element to heat the surface layer. The electrostatic chuck of claim 34, wherein the at least one clamping power supply comprises at least one AC power supply, and wherein the at least one heater power supply comprises at least one DC power supply.