Deflectable pressure plate and method of deflecting a pressure plate

Abstract

A deflectable platen and method for deflecting the platen. The deflectable platen includes an annular sidewall; a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; a second layer coupled to the annular sidewall and disposed in parallel, spaced relationship with the first layer to define a gap between the first and second layers, the second layer having a second temperature control element associated with the second layer; and a controller coupled to the first and second temperature control elements and configured to operate the first and second temperature control elements to change the temperature of the first and second layers relative to each other, thereby deflecting the platen to more closely match the contour of a wafer.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of semiconductor device fabrication, and more particularly, to a deflectable platen and method of deflecting the platen that facilitates efficient clamping of a semiconductor wafer. Background Art

[0002] During ion implantation and certain other processes performed during semiconductor device fabrication, a semiconductor wafer is typically placed on a flat platen. Commonly, the semiconductor wafer is secured to the platen by electrostatic clamping, where a voltage is applied between electrodes embedded in the platen and the resulting electric field secures the semiconductor wafer to the platen. Electrostatic clamping is preferred over mechanical clamping because mechanical clamping can damage and / or contaminate the semiconductor wafer.

[0003] The ability of the pressure plate to securely clamp the semiconductor wafer to the pressure plate via electrostatic clamping depends largely on the proximity of the bottom surface of the semiconductor wafer to the top surface of the pressure plate. Ideally, these surfaces are flat and placed in smooth, continuous contact with each other. In some cases, the semiconductor wafer may warp (e.g., deflect by as much as 20 thousandths of an inch (milli-inch)), thereby creating a relatively large gap between the bottom surface of the semiconductor wafer and the top surface of the pressure plate. This can result in weak or ineffective electrostatic clamping. This problem can be exacerbated if the semiconductor wafer and pressure plate are exposed to high-temperature or cryogenic processes (e.g., during high-temperature or low-temperature ion implantation), where incoherent deflection of the semiconductor wafer and pressure plate can increase the size of the gap between the semiconductor wafer and the pressure plate.

[0004] Therefore, minimizing the surface-to-surface proximity between the semiconductor wafer and the platen is desirable to facilitate safe electrostatic clamping between the semiconductor wafer and the platen.With respect to these and other considerations, the present improvements may be useful. Summary of the Invention

[0005] This summary is provided to introduce a series of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] An exemplary embodiment of a deflectable pressure plate according to the present disclosure may include: an annular sidewall; a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; and a second layer coupled to the annular sidewall and disposed in a parallel, spaced relationship with the first layer to define a gap between the first layer and the second layer, the second layer having a second temperature control element associated with the second layer.

[0007] Another exemplary embodiment of a deflectable platen according to the present disclosure may include: an annular sidewall; a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; a second layer coupled to the annular sidewall and disposed in a parallel, spaced relationship with the first layer to define a gap between the first layer and the second layer, the second layer having a second temperature control element associated with the second layer; and a controller coupled to the first temperature control element and the second temperature control element and configured to operate the first temperature control element and the second temperature control element to change the temperature of the first layer and the second layer relative to each other, thereby deflecting the platen to more closely match the contour of the wafer.

[0008] An exemplary embodiment of a method of deflecting a platen according to the present disclosure may include: providing an annular sidewall; providing a first layer, the first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; providing a second layer, the second layer coupled to the annular sidewall and disposed in a parallel, spaced relationship with the first layer so as to define a gap between the first layer and the second layer, the second layer having a second temperature control element associated with the second layer; and changing the temperature of at least one of the first layer and the second layer using the first temperature control element and the second temperature control element. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] By way of example, various embodiments of the disclosed apparatus will now be described with reference to the accompanying drawings, in which:

[0010] Figure 1A is a top view illustrating an exemplary embodiment of a deflectable pressure plate according to the present disclosure.

[0011] Figure 1B is shown along Figure 1A A cross-sectional side view of the deflectable pressure plate is shown along line AA.

[0012] Figure 2A is a diagram showing a semiconductor wafer with a convex deflected thereon. Figure 1A and Figure 1B A cross-sectional side view of the deflectable pressure plate is shown.

[0013] Figure 2B is shown in a convex deflected state Figure 2A A cross-sectional side view of the deflectable pressure plate is shown.

[0014] Figure 2C FIG. 1 is a diagram showing a semiconductor wafer with a concave deflected surface provided thereon and in a concave deflected state. Figure 1A and Figure 1B A cross-sectional side view of the deflectable pressure plate is shown.

[0015] Figure 3 is a flow chart illustrating an exemplary embodiment of a method of deflecting a platen according to the present disclosure. DETAILED DESCRIPTION

[0016] The present embodiments will now be described more fully below with reference to the accompanying drawings, some of which are shown. The subject matter of the present disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the subject matter to those skilled in the art. Like numbers refer to like elements throughout the drawings.

[0017] Reference Figure 1A and Figure 1B , which respectively illustrate a top view and a cross-sectional side view of a deflectable pressure plate 10 (hereinafter "pressure plate 10") according to an exemplary embodiment of the present disclosure. The pressure plate 10 can be elastically deformable (as further described below) to provide a close clearance relationship between the top surface of the pressure plate 10 and the bottom surface of a warped or curved semiconductor wafer disposed on the pressure plate 10, thereby facilitating effective clamping between the top surface of the pressure plate 10 and the bottom surface of the semiconductor wafer.

[0018] The press plate 10 may include a first generally planar layer 12 and a second generally planar layer 14 disposed in parallel, vertically spaced relationship (i.e., in a direction parallel to the Figure 1B The first and second layers 12 and 14 are spaced apart from each other in the direction of the Y axis shown in FIG or in a direction perpendicular to the X axis, thereby defining a gap 15 between the first layer 12 and the second layer 14. The circumferential edge of the first layer 12 and the circumferential edge of the second layer 14 can be connected to an annular sidewall 16 surrounding the first and second layers 12 and 14, as further described below. In various embodiments, the first and second layers 12 and 14 can be formed of a 6.0×10 -6 / ℃ and 8.0×10 -61 / °C. In a specific example, the first layer 12 and the second layer 14 may be formed of a ceramic, including but not limited to alumina, zirconia, or aluminum nitride. The present disclosure is not limited thereto. The first layer 12 and / or the second layer 14 may alternatively be formed of other materials with relatively high or relatively low CTEs, including but not limited to aluminum, silver, copper, and alloys thereof, or quartz.

[0019] The sidewalls 16 of the platen 10 may be formed from a dielectric material having a relatively low CTE or a CTE similar to the CTE of the material of the first layer 12 and the second layer 14. In various examples, the sidewalls 16 may be formed from a dielectric material having a CTE less than 6.0×10 -6 / ℃(for example, between 2.0×10 -6 / ℃ and 4.0×10 -6 12 and 14. In some embodiments, the sidewalls 16 may be formed of a material having a CTE between 100°C and 100°C. In a specific example, the sidewalls 16 may be formed of a ceramic (e.g., aluminum nitride or aluminum oxide). The present disclosure is not limited thereto. The sidewalls 16 may alternatively be formed of other dielectric materials, including but not limited to other ceramics and various composite materials. The sidewalls 16 may be connected to the edges of the first layer 12 and the edges of the second layer 14 by brazing, welding, heat-resistant adhesives, various mechanical fasteners, glass bonding, and / or other techniques suitable for bonding or fastening the material of the sidewalls 16 to the materials of the first layer 12 and the second layer 14. As will be described in more detail below, the sidewalls 16 may mechanically convert expansion and contraction of the first layer 12 and the second layer 14 into each other.

[0020] The first layer 12 and the second layer 14 may include respective first heating elements 20 and second heating elements 22 associated with the first layer 12 and the second layer 14. Figure 1BIn the embodiment of the press plate shown in , the first heating element 20 and the second heating element 22 may be embedded in the first layer 12 and the second layer 14. The first heating element 20 and the second heating element 22 may include one or more wires, cables, plates, ribbons, etc. connected to one or more power sources (not shown). The first heating element 20 and the second heating element 22 may be independently operable to selectively and independently heat the first layer 12 and the second layer 14. In various examples, the first heating element 20 and the second heating element 22 may heat the first layer 12 and the second layer 14 to a temperature exceeding 800 degrees Celsius (e.g., in the range of 800 degrees Celsius to 1200 degrees Celsius), respectively. The present disclosure is not limited thereto. The gap 15 separating the first layer 12 and the second layer 14 may be maintained under vacuum or near vacuum, and thus may provide thermal separation between the first layer 12 and the second layer 14. Specifically, gap 15 can prevent all or most of the heat generated by first heating element 20 from being transferred to second layer 14, and can prevent all or most of the heat generated by second heating element 22 from being transferred to first layer 12. In various embodiments, press plate 10 can additionally or alternatively include one or more layers of thermally insulating material disposed between first layer 12 and second layer 14.

[0021] The second layer 14 of the press plate 10 may have a plurality of electrodes 23 associated with the second layer 14. For example, Figure 1B In the embodiment of the press plate shown in , the electrode 23 may be embedded in the second layer 14. In various alternative embodiments of the press plate 10, the electrode 23 may be embedded in a separate layer of dielectric material disposed on top of the second layer 14. The present disclosure is not limited thereto. The electrode 23 may be connected to an electrical power source (not shown) and may be arranged and configured to operate in a conventional electrostatic clamping manner familiar to those skilled in the art. Specifically, by applying a voltage across the electrode 23, an electric field may be generated and the semiconductor wafer may be held to the press plate 10 by electrostatic forces. The strength of the electrostatic force acting on the wafer will depend in part on the proximity of the wafer to the electrode 23. Ideally, the contour of the bottom surface of the wafer will match or nearly match the contour of the top surface of the press plate 10 (for example, if these surfaces are flat or nearly flat), thereby establishing the shortest possible distance between the electrode 23 and the wafer to provide a strong electrostatic coupling between the electrode 23 and the wafer. In some cases, the wafer (e.g. Figure 2A The semiconductor wafer 24 shown in FIG. 1 (hereinafter “wafer 24”) may warp or bow (e.g., deflect up to 20 thou, and possibly more than 20 thou), and may present a concave bottom surface relative to the generally flat top surface of the platen 10 (for purposes of illustration, Figure 2AThe deflection of wafer 24 shown in FIG is exaggerated. The resulting gap 25 between wafer 24 and platen 10 weakens the electrostatic force acting on wafer 24, thereby resulting in poor electrostatic clamping between platen 10 and wafer 24.

[0022] In various alternative embodiments of the platen 10, the electrodes 23 may be omitted and various mechanical fixtures 27 familiar to those skilled in the art may be used. Figure 1B 10 ). As with electrostatic coupling, the contour of the bottom surface of wafer 24 will ideally match or nearly match the contour of the top surface of platen 10 (e.g., if these surfaces are flat or nearly flat) to facilitate optimal contact and ensure mechanical coupling between the bottom surface of wafer 24 and the top surface of platen 10, as well as to facilitate optimal thermal coupling between platen 10 and wafer 24. Good thermal coupling may be desirable if platen 10 is configured to heat or cool a wafer disposed on platen 10 (e.g., via heat transfer from an inert gas introduced between platen 10 and wafer 24). If wafer 24 warps or bows, the resulting gap 25 between wafer 24 and platen 10 may be detrimental to ensuring mechanical clamping and / or establishing effective thermal coupling between wafer 24 and platen 10.

[0023] Reference Figure 2B , showing the press plate 10 in a convex deflected state. Specifically, the second heating element 22 is activated, and the first heating element 20 is not activated or is activated at a lower power, so that the second layer 14 is heated while the first layer 12 is not heated or is heated to a lower temperature than the second layer 14. When heated, the second layer 14 may exhibit thermal expansion according to its CTE. Since the second layer 14 is connected to the first layer 12 by the side wall 16, and since the unheated first layer 12 does not expand (or expands at a slower rate and / or to a smaller extent than the heated second layer 14), the expansion of the second layer 14 in the radial direction may cause the upper portion of the side wall 16 to deflect outward, which in turn causes the edges of the first layer 12 and the second layer 14 to be pulled or deflected downward, thereby producing a phenomenon such as Figure 2B The projection of the pressure plate 10 is shown in FIG. Figure 2A The undeflected state of the platen 10 shown in FIG2 can cause the contour of the top surface of the platen 10 to more closely match the contour of the bottom surface of the wafer 24 to reduce the size of the gap 25 between the wafer 24 and the platen 10. In the case of electrostatic clamping, the smaller gap 25 and the closer proximity of the electrode 23 of the deflected platen 10 to the wafer 24 provide a stronger electrostatic force on the wafer 24 than that provided by the electrostatic clamp. Figure 2AThe electrostatic force exerted by the undeflected platen 10 shown in FIG is stronger, thereby producing a better electrostatic coupling between the platen 10 and the wafer 24. In the case of mechanical clamping, relative to Figure 2A The smaller gap 25 achieved by the deflected platen 10 facilitates a more secure clamping of the wafer 24 to the platen 10 and creates a better thermal coupling between the platen 10 and the wafer 24, as shown in FIG.

[0024] The platen 10 may also be deflected in a concave direction to accommodate a curved or warped semiconductor wafer that presents a convex surface relative to the top surface of the platen 10. For example, referring to Figure 2C , showing a press plate 10 in a recessed deflected state with a recessed deflected semiconductor wafer 28 (hereinafter "wafer 28") disposed thereon. Specifically, the first heating element 20 is activated and the second heating element 22 is inactivated (or activated at a lower power), thereby heating the first layer 12 relative to the second layer 14. When heated, the first layer 12 may exhibit thermal expansion according to its CTE. Because the first layer 12 is connected to the second layer 14 by the side wall 16, and because the unheated second layer 14 does not expand (or expands at a slower rate and / or to a smaller extent than the heated first layer 12), the expansion of the first layer 12 in the radial direction may cause the lower portion of the side wall 16 to deflect outward, which in turn causes the edge of the first layer 12 and the edge of the second layer 14 to be pulled or deflected upward, thereby producing the following. Figure 2C . Thus, the contour of the top surface of the press plate 10 can be made to more closely match the contour of the bottom surface of the wafer 28, thereby producing better electrostatic or mechanical coupling between the press plate 10 and the wafer 28 as described above.

[0025] In various examples, the first and second layers 12, 14 may be heated to a temperature between 300 degrees Celsius and 800 degrees Celsius to achieve a target amount of deflection. In a specific, non-limiting example, the press plate 10 may exhibit a convex deflection of 18 thou when the second layer is heated to a temperature of 500 degrees Celsius, and may exhibit a convex deflection of 18 thou when the first layer is heated to a temperature of 500 degrees Celsius. The present disclosure is not limited in this regard. The degree of deflection in the press plate 10 will depend on many factors, including, but not limited to, the CTE of the first and second layers 12, 14, the amount of heat applied to the first and second layers 12, 14, the diameters of the first and second layers 12, 14, and the thicknesses of the first and second layers 12, 14.

[0026] In various embodiments, during heating of either of the first layer 12 and the second layer 14, the deflection stress on the first layer 12 and the second layer 14 may be less than the yield strength of the material of the first layer 12 and the second layer 14. Thus, when the first layer 12 and the second layer 14 are allowed to cool to room temperature, the press plate 10 may return to a state such as Figure 1B , the platen 10 is shown in its original, substantially flat state. Thus, by varying the amount of heat applied to the first and second layers 12, 14, the platen 10 can be controllably deflected to varying degrees (e.g., from 0 thou to 20 thou) in either direction (i.e., concave or convex) to match or approximate the contour of a wafer having varying degrees of deflection disposed thereon, thereby providing an effective electrostatic or mechanical clamp between the platen 10 and the wafer. Thus, the deflection of an incoming wafer can be measured (e.g., by a contact sensor, image analysis, etc.), and a controller 29 operatively coupled to the platen 10 can, upon receiving data representing the measured deflection of the wafer, direct operation of the first and second heating elements 20, 22 to deflect the platen 10 to match or approximate the contour of the incoming wafer.

[0027] Although the press plate 10 has been described above as including embedded first and second heating elements 20, 22 for controllably and selectively heating the first and second layers 12, 14, various alternative embodiments of the press plate 10 are contemplated in which the first and second heating elements 20, 22 described above and illustrated in the figures may instead be cooling elements for controllably and selectively cooling the first and second layers 12, 14. Accordingly, the first and second heating elements 20, 22 may alternatively be referred to herein as "cooling elements 20, 22," or more generally, as "temperature control elements 20, 22." The cooling elements may be or include various channels, conduits, tubes, pipes, ducts, etc. embedded in, disposed on, or extending through the first and second layers 12, 14 for circulating a cooling fluid (e.g., water, liquid nitrogen, etc.) through the various channels, conduits, tubes, pipes, ducts, etc. The cooling elements 20, 22 can be used to cool the first layer 12 and / or the second layer 14 to a temperature in a range of, for example, between 0 degrees Celsius and -150 degrees Celsius. By cooling one of the first layer 12 and the second layer 14 without cooling the other of the first layer 12 and the second layer 14, the cooled layer can exhibit thermal contraction according to its CTE. Because the first layer 12 and the second layer 14 are connected to each other by the sidewall 16, and because the uncooled layer does not contract (or contracts at a slower rate and / or to a lesser extent than the cooled layer), the contraction of the cooled layer in the radial direction can cause the sidewall 16 to deflect, which in turn causes the edge of the first layer 12 and the edge of the second layer 14 to be pulled or deflected upward or downward depending on the cooled layer, thereby producing a Figure 2B and Figure 2C In various other embodiments, the first layer 12 and the second layer 14 can include heating elements and cooling elements such as those described above.

[0028] Reference Figure 3 , a flow chart illustrating an exemplary method of deflecting a pressure plate according to the present disclosure is shown. Figures 1A to 2C The method is illustrated using the example of the press plate 10 shown in FIG.

[0029] At block 100 of the exemplary method, a first layer 12 and a second layer 14 may be provided and coupled to the annular sidewall 16, for example, by brazing, welding, heat-resistant adhesives, various mechanical fasteners, glass bonding, and / or other techniques suitable for bonding or fastening the material of the sidewall 16 to the material of the first layer 12 and the second layer 14. The first layer 12 and the second layer 14 may be disposed in a parallel, spaced-apart relationship such that a gap 15 is defined therebetween, and the gap 15 may be maintained under or near a vacuum to provide thermal insulation between the first layer 12 and the second layer 14. The first layer 12 and the second layer 14 may include respective first and second temperature control elements 20 and 22 associated with (e.g., embedded in) the first layer 12 and the second layer 14. At block 110 of the exemplary method, the second layer 14 may be provided with an electrode 23 associated with (e.g., embedded in) the second layer 14 to facilitate electrostatic clamping of the wafer to the platen 10. In various alternative embodiments, the electrode 23 may be omitted and a mechanical clamp 27 may be implemented.

[0030] At block 120 of the exemplary method, the deflection of the incoming wafer may be measured (e.g., by contact sensors, imaging analysis, etc.), and the controller 29 operatively coupled to the platen 10 may, upon receiving data representing the measured deflection of the wafer, direct the operation of the first temperature control element 20 and the second temperature control element 22 to deflect the platen 10 to match or approximate the contour of the incoming wafer. In one example, where the first temperature control element 20 and the second temperature control element 22 are heating elements, at block 130a of the exemplary method, the second temperature control element 22 may be activated to heat the second layer 14 relative to the first layer 12. When heated, the second layer 14 may exhibit thermal expansion according to its CTE. Because the second layer 14 is connected to the first layer 12 by the sidewall 16, and because the unheated first layer 12 does not expand (or expands at a slower rate and / or to a lesser extent than the heated second layer 14), the expansion of the second layer 14 in the radial direction can cause the upper portion of the sidewall 16 to deflect outward, which in turn causes the edges of the first layer 12 and the second layer 14 to be pulled or deflected downward, thereby producing the following: Figure 2B The protrusions of the pressure plate 10 shown in FIG are deflected. Thus, the profile of the top surface of the pressure plate 10 can be made to more closely match the profile of the bottom surface of the feed wafer.

[0031] In another example, where the first temperature control element 20 and the second temperature control element 22 are heating elements, at block 130b of the exemplary method, the first temperature control element 20 may be activated to heat the first layer 12 relative to the second layer 14. When heated, the first layer 12 may exhibit thermal expansion according to its CTE. Because the first layer 12 is connected to the second layer 14 by the sidewall 16, and because the unheated second layer 14 does not expand (or expands at a slower rate than the first layer 12 and / or to a lesser extent than the heated first layer 12), the expansion of the first layer 12 in the radial direction may cause the lower portion of the sidewall 16 to deflect outward, which in turn may cause the edge of the first layer 12 and the edge of the second layer 14 to be pulled or deflected upward, thereby producing a radial expansion. Figure 2C The concave deflection of the platen 10 shown in FIG. 1A can thereby make the profile of the top surface of the platen 10 more closely match the profile of the incoming wafer.

[0032] In another example, where the first temperature control element 20 and the second temperature control element 22 are cooling elements, at block 130c of the exemplary method, the first temperature control element 20 may be activated to cool the first layer 12 relative to the second layer 14. When cooled, the first layer 12 may exhibit thermal contraction according to its CTE. Because the first layer 12 is connected to the second layer 14 by the sidewall 16, and because the uncooled second layer 14 does not contract (or contracts at a slower rate and / or to a lesser extent than the first layer 12), the contraction of the first layer 12 in the radial direction may cause the lower portion of the sidewall 16 to deflect inwardly, which in turn causes the edge of the first layer 12 and the edge of the second layer 14 to be pulled or deflected downward, thereby producing a pressure drop as shown in FIG. Figure 2B The protrusions of the platen 10 shown in FIG are deflected. Thus, the profile of the top surface of the platen 10 can be made to more closely match the profile of the incoming wafer.

[0033] In another example, where the first temperature control element 20 and the second temperature control element 22 are cooling elements, at block 130d of the exemplary method, the second temperature control element 22 may be activated to cool the second layer 14 relative to the first layer 12. When cooled, the second layer 14 may exhibit thermal contraction according to its CTE. Because the second layer 14 is connected to the first layer 12 by the sidewall 16, and because the uncooled first layer 12 does not contract (or contracts at a slower rate and / or to a lesser extent than the cooled second layer 14), the contraction of the second layer 14 in the radial direction may cause the upper portion of the sidewall 16 to deflect inwardly, which in turn may cause the edge of the first layer 12 and the edge of the second layer 14 to be pulled or deflected upwardly, thereby producing the following: Figure 2C The concave deflection of the platen 10 shown in FIG. 1A can thereby make the profile of the top surface of the platen 10 more closely match the profile of the bottom surface of the incoming wafer.

[0034] As will be appreciated by those skilled in the art, the deflectable pressure plate 10 described above offers significant advantages over conventional pressure plates. For example, the pressure plate 10 can be selectively and dynamically deflected by controlled application of heating (or cooling) to the first and second layers 12, 14 to quickly and conveniently facilitate effective clamping of wafers having varying degrees of concave or convex deflection. Furthermore, the ability of the pressure plate 10 to conform to the contours of a wafer disposed thereon facilitates efficient heat transfer between the pressure plate 10 and the wafer (e.g., for heating and / or cooling the wafer).

[0035] The scope of the present disclosure is not limited by the specific embodiments described herein. In fact, based on the foregoing description and accompanying drawings, various other embodiments of the present disclosure and various modifications to the present disclosure in addition to the embodiments and modifications described herein will also be apparent to those of ordinary skill in the art. Therefore, these other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, although the present disclosure has been described herein in the context of specific embodiments in specific environments for specific purposes, those of ordinary skill in the art will recognize that its validity is not limited thereto. The embodiments of the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth above should be interpreted in light of the full breadth and spirit of the disclosure as described herein.

Claims

1. A deflectable pressure plate comprising: annular sidewall; a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; as well as a second layer coupled to the annular sidewall and disposed in parallel, spaced relationship with the first layer so as to define a gap therebetween, the second layer having a second temperature control element associated therewith, wherein the gap is under vacuum and provides thermal insulation between the first layer and the second layer.

2. The deflectable platen of claim 1 further comprising a plurality of electrodes associated with the second layer to facilitate electrostatic clamping of a wafer to the deflectable platen.

3. The deflectable pressure plate of claim 1, wherein the first temperature control element and the second temperature control element are first and second heating elements.

4. The deflectable pressure plate of claim 3, wherein the first and second heating elements comprise one or more of wires, plates, and ribbons connected to one or more sources of electrical power.

5. The deflectable pressure plate of claim 3, wherein the first heating element and the second heating element are independently controllable for independently heating the first layer and the second layer to a temperature exceeding 800 degrees Celsius.

6. The deflectable pressure plate of claim 1, wherein the first and second temperature control elements are first and second cooling elements.

7. The deflectable pressure plate of claim 6, wherein the first cooling element and the second cooling element include channels for circulating a cooling fluid.

8. The deflectable pressure plate of claim 6, wherein the first cooling element and the second cooling element are independently controllable for independently cooling the first layer and the second layer to a temperature within a range of 0 degrees Celsius to -150 degrees Celsius.

9. The deflectable pressure plate of claim 1, wherein the first layer and the second layer are made of a material having a thickness between 6.0×10 -6 / °C and 8.0 × 10 -6 / ℃ is the range of thermal expansion coefficient of the material.

10. The deflectable pressure plate of claim 1, wherein the annular sidewall is formed of a material having a thickness of less than 6.0 × 10 -6 / ℃ thermal expansion coefficient of the material.

11. A deflectable pressure plate comprising: annular sidewall; a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; a second layer coupled to the annular sidewall and disposed in parallel, spaced relationship with the first layer so as to define a gap between the first layer and the second layer, the second layer having a second temperature control element associated with the second layer; as well as a controller coupled to the first temperature control element and the second temperature control element and configured to operate the first temperature control element and the second temperature control element to change the temperature of the first layer and the second layer relative to each other to deflect the deflectable platen to more closely match the contour of the wafer, wherein the gap is under vacuum and provides thermal insulation between the first layer and the second layer.

12. A method of deflecting a platen, comprising: providing an annular sidewall; providing a first layer coupled to the annular sidewall, the first layer having a first temperature control element associated with the first layer; providing a second layer coupled to the annular sidewall and disposed in parallel, spaced relationship with the first layer so as to define a gap between the first layer and the second layer, the second layer having a second temperature control element associated with the second layer; as well as changing the temperature of at least one of the first layer and the second layer using the first temperature control element and the second temperature control element, wherein the gap is under vacuum and provides thermal insulation between the first layer and the second layer.

13. The method of deflecting a platen of claim 12, further comprising providing the second layer with an electrode associated with the second layer to facilitate electrostatic clamping of a wafer to the platen.

14. The method of deflecting a platen according to claim 12, wherein the first temperature control element and the second temperature control element are a first heating element and a second heating element, the method further comprising activating the second heating element to heat the second layer relative to the first layer, thereby producing thermal expansion of the second layer and convex deflection of the platen.

15. The method of deflecting a platen according to claim 12, wherein the first temperature control element and the second temperature control element are a first heating element and a second heating element, the method further comprising activating the first heating element to heat the first layer relative to the second layer, thereby producing thermal expansion of the first layer and concave deflection of the platen.

16. The method of deflecting a platen according to claim 12, wherein the first temperature control element and the second temperature control element are a first cooling element and a second cooling element, the method further comprising activating the second cooling element to cool the second layer relative to the first layer, thereby producing thermal contraction of the second layer and concave deflection of the platen.

17. The method of deflecting a platen according to claim 12, wherein the first temperature control element and the second temperature control element are a first cooling element and a second cooling element, the method further comprising activating the first cooling element to cool the first layer relative to the second layer, thereby producing thermal contraction of the first layer and convex deflection of the platen.

18. The method of deflecting a platen according to claim 12, further comprising: measuring a deflection of a wafer disposed on the platen; communicating data representing the measured deflection of the wafer to a controller operatively connected to the first temperature control element and the second temperature control element; as well as At least one of the first and second temperature control elements is activated by the controller to change the temperature of the first and second layers to deflect the platen to more closely match a contour of the wafer.

19. The method of deflecting a platen of claim 18, wherein the deflection of the wafer is measured using one of a contact sensor and image analysis.

Images