DEFLECTABLE PLATEN AND RELATED METHODS - Patent application

Abstract

A deflectable platen including a first layer formed from a material having a first coefficient of thermal expansion (CTE) and a second layer bonded to the first layer and having a second CTE different from the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer.

Description

[Technical Field]

[0001] TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate generally to the field of semiconductor device manufacturing, and more specifically to a deflectable platen for facilitating effective electrostatic clamping of semiconductor wafers. [Background technology]

[0002]

[0002] A semiconductor wafer is typically placed on a flat platen during ion implantation and certain other processes performed during the fabrication of semiconductor devices. Generally, the semiconductor wafer is secured to the platen via an electrostatic clamp, where a voltage is applied between electrodes embedded in the platen, and the resulting electric field holds the semiconductor wafer to the platen. Electrostatic clamps are preferred over mechanical clamps because mechanical clamps can damage and / or contaminate the semiconductor wafer.

[0003] The ability of a platen to securely hold a semiconductor wafer to the platen via electrostatic clamping depends heavily on the proximity of the bottom surface of the semiconductor wafer to the top surface of the platen. Ideally, both surfaces are planar and positioned in flat, continuous contact with one another. In some cases, semiconductor wafers may be bowed (e.g., up to 20 thousandths of an inch), resulting in a relatively large gap between the bottom surface of the semiconductor wafer and the top surface of the platen. This can weaken or render the electrostatic clamp ineffective. This problem can be exacerbated when the semiconductor wafer and platen are exposed to high-temperature processing (e.g., during high-temperature ion implantation), where inconsistent bowing of the semiconductor wafer and platen can increase the gap between them.

[0004]

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

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

[0006]

[0006] A flexible platen according to a non-limiting embodiment of the present disclosure can include a first layer formed of a material having a first coefficient of thermal expansion (CTE) and a second layer bonded to the first layer and having a second CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of the wafer to the second layer, the second CTE being different from the first CTE.

[0007]

[0007] A flexible platen according to another non-limiting embodiment of the present disclosure may include a first layer formed of a material having a first CTE, a second layer bonded to the first layer and having a second CTE greater than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of the wafer to the second layer, and a heat trace disposed between the first layer and the second layer and adapted to controllably heat the first layer and the second layer.

[0008]

[0008] A method of deflecting a platen according to a non-limiting embodiment of the present disclosure may include providing a first layer formed of a material having a first CTE; providing a second layer bonded to the first layer and having a second CTE different from the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of the wafer to the second layer; and may include one of heating the first layer and the second layer to a temperature in the range of 300 degrees Celsius to 600 degrees Celsius; and cooling the first layer and the second layer to a temperature in the range of -50 degrees Celsius to -150 degrees Celsius.

[0009]

[0009] By way of example, various embodiments of the disclosed apparatus are described below with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0010] [Figure 1A] 1 is a cross-sectional side view of an exemplary embodiment of a flexible platen according to the present disclosure with a semiconductor wafer disposed thereon; [Figure 1B] 1B is a cross-sectional side view of the deflectable platen of FIG. 1A in a deflected state with a semiconductor wafer disposed thereon. [Figure 1C] 1B is a cross-sectional side view showing the deflectable platen of FIG. 1A being resiliently returned to an undeflected state. [Figure 2] FIG. 10 is a flow diagram illustrating a method for deflecting a platen according to one embodiment of the present disclosure. [Figure 3A] 1 is a cross-sectional side view of another exemplary embodiment of a flexible platen according to the present disclosure with a semiconductor wafer disposed thereon. [Figure 3B] 3B is a cross-sectional side view of the deflectable platen of FIG. 3A in a deflected state with a semiconductor wafer disposed thereon. [Figure 3C] 3B is a cross-sectional side view of the deflectable platen of FIG. 3A plastically maintained in a deflected state. [Figure 4] FIG. 10 is a flow diagram illustrating another method for deflecting a platen according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0018] The present embodiments will be more fully described with reference to the accompanying drawings, in which several embodiments are shown. The subject matter of this disclosure may be embodied in many different forms and should not be construed as 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. In the drawings, like numbers refer to like elements throughout.

[0012]

[0019] 1A, a cross-sectional side view of a flexible platen 10 (hereinafter "platen 10") according to an exemplary embodiment of the present disclosure is shown. Platen 10 may be elastically deformable (as further described below) to provide a close clearance relationship between the top surface of platen 10 and the bottom surface of a cambered or curved semiconductor wafer placed thereon to facilitate effective electrostatic clamping therebetween.

[0013]

[0020] The platen 10 may include a generally planar first layer 12 formed of a first material and a generally planar second layer 14 formed of a second material disposed on the first layer 12. The first material may have a first coefficient of thermal expansion (CTE), and the second material may have a second CTE, which may be greater than the first CTE. The first layer 12 and the second layer 14 may be bonded together flat, such as by brazing or other techniques suitable for bonding the first and second materials together. In various embodiments, the platen 10 may include a heat trace 15 disposed or “sandwiched” between the first layer 12 and the second layer 14. The heat trace 15 may include an electric heating element (e.g., one or more wires, cables, plates, tapes, etc.) connected to a power source (not shown). The heat trace 15 may be flexible, for example, adapted to withstand deflection of the platen 10 of up to at least 20 thou (as described below). By actuating the heat trace 15, the adjacent first and second layers 12, 14 of the platen 10 may be controllably heated, as described further below.

[0014]

[0021] In one embodiment, the first layer 12 of the platen 10 is 6.0×10 -7 / °C (e.g., 2.0 x 10 -7 / ℃~4.0×10 -7 / °C). In particular embodiments, first layer 12 may be formed of quartz. The disclosure is not limited in this respect. First layer 12 may alternatively be formed of other relatively low CTE materials, including, but not limited to, carbon, silicon, silicon nitride, silicon carbide, aluminum nitride, INVAR, KOVAR, molybdenum, tungsten, tantalum, titanium, and alloys thereof. In one embodiment, second layer 14 of platen 10 is formed of a material having a relatively higher CTE than first layer 12 (e.g., 6.0×10 -7 / ℃~8.0×10 -7 / °C). In particular examples, second layer 14 may be formed from a ceramic, including, but not limited to, aluminum oxide. The disclosure is not limited in this respect. Alternatively, second layer 14 may be formed from other relatively high CTE materials, including, but not limited to, aluminum, silver, copper, and alloys thereof.

[0015]

[0022] The second layer 14 of the platen 10 may have a plurality of electrodes 16 embedded therein. The electrodes 16 may be connected to a power source (not shown) and may be positioned and configured to operate in a conventional electrostatic clamping manner well known to those skilled in the art. In particular, by applying a voltage across the electrodes 16, an electric field may be generated that may hold a semiconductor wafer 18 (hereinafter "wafer 18") to the platen 10 via electrostatic forces. The strength of the electrostatic force acting on the wafer 18 depends in part on the proximity of the wafer 18 to the electrodes 16. Ideally, the contour of the bottom surface of the wafer 18 matches or nearly matches the contour of the top surface of the platen 10 (e.g., if both surfaces are flat or nearly flat), thereby establishing the shortest possible distance between the electrodes 16 and the wafer 18 and providing a strong electrostatic coupling therebetween. In some cases, a wafer, such as wafer 18 shown in Figure 1A, may bow or curve (e.g., bow up to 20 ohms, and sometimes more) and present a concave bottom surface to the generally flat top surface of platen 10 (the bowing of wafer 18 as shown in Figure 1A is exaggerated for illustrative purposes). The resulting gap 20 between wafer 18 and platen 10 attenuates the electrostatic force acting on wafer 18, resulting in reduced electrostatic clamping between platen 10 and wafer 18.

[0016]

[0023] Referring to FIG. 1B, the platen 10 is shown in a deflected state. In particular, the heat trace 15 is activated, thereby heating the first layer 12 and the second layer 14 of the platen 10. Because the CTE of the second layer 14 is greater than the CTE of the first layer 12, the heated second layer 14 may expand more (i.e., more rapidly and / or to a greater extent) than the heated first layer 12, resulting in a convex deflection of the platen 10. Thus, the contour of the top surface of the platen 10 may more closely match the contour of the bottom surface of the wafer 18, reducing the size of the gap 20 therebetween compared to the undeflected state of the platen 10 shown in FIG. 1A. In various embodiments, the platen 10 may be heated to a temperature between 300° C. and 600° C. In a specific, non-limiting embodiment, the platen 10 may exhibit a deflection of 18 ohms when heated to a temperature of 500° C. The present disclosure is not limited in this respect. The smaller gap 20 and closer proximity of the electrode 16 to the wafer 18 facilitated by the deflected platen 10 provides a stronger electrostatic force acting on the wafer 18 compared to the electrostatic force applied by the undeflected platen 10 shown in FIG. 1A, resulting in better electrostatic coupling between the platen 10 and the wafer 18.

[0017]

[0024] The degree of deflection in the heated platen 10 will depend on many factors, including, but not limited to, the CTE of the first layer 12 and the second layer 14, the amount of heat applied to the first layer 12 and the second layer 14, the diameter of the first layer 12 and the second layer 14, and the thickness of the first layer 12 and the second layer 14. In a non-limiting embodiment, the thickness of the first layer 12 may be 4 millimeters and the thickness of the second layer 14 may be 4 millimeters. In another non-limiting embodiment, the thickness of the first layer 12 may be 6 millimeters and the thickness of the second layer 14 may be 4 millimeters. In another non-limiting embodiment, the thickness of the first layer 12 may be 8 millimeters and the thickness of the second layer 14 may be 4 millimeters. The present disclosure is not limited in this respect, and the thicknesses of the first layer 12 and the second layer 14 may differ from those described above. Additionally, although the platen 10 has been described as including integrated heat trace 15 for controllably heating the platen 10, embodiments of the platen 10 are contemplated in which the heat trace 15 is omitted and the platen 10 is heated by an external heat source (e.g., an oven).

[0018]

[0025] In various embodiments, the deflection stress of platen 10 during heating may be less than the yield strength of the material of first layer 12 and / or second layer 14. Thus, when heat trace 15 (or other heat source) is turned off and platen 10 is allowed to cool to room temperature, platen 10 can return to its original, substantially flat state, as shown in FIG. 1C. Thus, by varying the amount of heat applied to first layer 12 and second layer 14, platen 10 can be controllably deflected to various degrees (e.g., 0 to 20 ohms) to conform to or closely approximate the contours of wafers with various degrees of deflection placed thereon and provide effective electrostatic clamping therebetween.

[0019]

[0026] Referring to Figure 2, a flow diagram illustrating an exemplary method for deflecting a platen according to the present disclosure is shown. This method will now be described in relation to the illustration of platen 10 shown in Figures 1A-1C.

[0020]

[0027] At block 100 of the exemplary method, a first layer 12 may be provided and may be formed from a material having a first CTE. At block 110 of the method, a second layer 14 may be provided and may be formed from a material having a second CTE, and the second layer 14 may be flat-bonded to the first layer 12, such as by brazing or other suitable techniques as described above. The second CTE may be greater than the first CTE. In various embodiments, the first layer 12 may have a CTE of 6.0×10 -7 / °C (e.g., 2.0 x 10 -7 / ℃~4.0×10 -7 / °C), and the second layer 14 may be formed from a material having a CTE of 6.0×10 -7 / ℃~8.0×10 -7 / °C. Embedded within the second layer 14 may be a plurality of electrodes 16. The electrodes 16 may be connected to a power source and may be positioned and configured to operate in the manner of conventional electrostatic clamping, as is well known to those skilled in the art.

[0021]

[0028] In block 120 of the exemplary method, heat trace 15 may be disposed (e.g., sandwiched) between first layer 12 and second layer 14. This may occur prior to or during bonding of second layer 14 to first layer 12. Heat trace 15 may include an electric heating element (e.g., one or more wires, cables, plates, tapes, etc.) connected to a power source.

[0022]

[0029] In block 130 of the exemplary method, the heat trace 15 may be activated, thereby heating the first layer 12 and the second layer 14. Because the CTE of the second layer 14 is greater than the CTE of the first layer 12, the heated second layer 14 may expand more (i.e., more quickly and / or to a greater extent) than the heated first layer 12, resulting in a convex deflection of the platen 10. Thus, as shown in FIG. 1B, the contour of the top surface of the platen 10 may more closely match the contour of the bottom surface of the wafer 18, reducing the size of the gap 20 therebetween compared to the undeflected state of the platen 10 shown in FIG. 1A.

[0023]

[0030] 3A, a cross-sectional side view is shown of a flexible platen 200 (hereinafter "platen 200") according to another exemplary embodiment of the present disclosure. Platen 200 may be plastically deformable (as described further below) to provide a close clearance relationship between the top surface of platen 200 and the bottom surface of a cambered or curved semiconductor wafer placed thereon to facilitate effective electrostatic clamping therebetween.

[0024]

[0031] The platen 200 may include a generally planar first layer 212 formed of a first material and a generally planar second layer 214 formed of a second material disposed on the first layer 212. The first material may have a first coefficient of thermal expansion (CTE), and the second material may have a second CTE, where the first CTE may be greater than the second CTE. The first layer 212 and the second layer 214 may be bonded together flat, such as by an epoxy or other technique suitable for bonding the first and second materials together.

[0025]

[0032] In one embodiment, the first layer 212 of the platen 200 is 20.0×10 -7 / °C (e.g., about 24.0 × 10 -7 / °C). In particular examples, first layer 212 may be formed from a porous aluminum alloy. The disclosure is not limited in this respect. Alternatively, first layer 212 may be formed from other relatively high CTE materials, including, but not limited to, aluminum, silver, copper, and alloys thereof. In one example, second layer 214 of platen 200 is formed from a material having a relatively lower CTE than first layer 112 (e.g., 6.0×10 -7 / ℃~8.0×10 -7 / °C). In particular examples, second layer 214 may be formed of a ceramic, including, but not limited to, aluminum oxide. The disclosure is not limited in this respect. Second layer 214 may alternatively be formed of other relatively low CTE materials, including, but not limited to, carbon, silicon, silicon nitride, silicon carbide, aluminum nitride, INVAR, KOVAR, molybdenum, tungsten, tantalum, titanium, and alloys thereof.

[0026]

[0033] The second layer 214 of the platen 200 may have a plurality of electrodes 216 embedded therein. The electrodes 216 may be connected to a power source (not shown) and may be positioned and configured to operate in a conventional electrostatic clamping manner well known to those skilled in the art. In particular, by applying a voltage across the electrodes 216, an electric field may be generated that may hold a semiconductor wafer 218 (hereinafter, "wafer 218") to the platen 200 via electrostatic forces. The strength of the electrostatic force acting on the wafer 218 depends in part on the proximity of the wafer 218 to the electrodes 216. Ideally, the contour of the bottom surface of the wafer 218 matches or nearly matches the contour of the top surface of the platen 200 (e.g., if both surfaces are flat), thus establishing the shortest possible distance between the electrodes 216 and the wafer 218 and providing a strong electrostatic coupling therebetween. In some cases, a wafer, such as wafer 218 shown in Figure 3A, may bow or curve (e.g., bow up to 20 thou, and in some cases more) and present a concave bottom surface to the generally flat top surface of platen 200. (The bowing of wafer 218 as shown in Figure 3A is exaggerated for illustrative purposes.) The resulting gap 220 between wafer 218 and platen 200 attenuates the electrostatic force acting on wafer 218, resulting in reduced electrostatic clamping between platen 200 and wafer 218.

[0027]

[0034] Referring to FIG. 3B, the platen 200 is shown in a deflected state. In particular, the platen has been rapidly and significantly cooled. In a non-limiting example, the platen 200 may be immersed in liquid nitrogen. The present disclosure is not limited in this respect. Because the CTE of the first layer 212 is greater than the CTE of the second layer 214, the cooled first layer 212 may contract (i.e., more quickly and / or to a greater extent) than the cooled second layer 214, resulting in a convex deflection of the platen 200. Thus, the contour of the top surface of the platen 200 may more closely match the contour of the bottom surface of the wafer 218, reducing the size of the gap 220 therebetween compared to the undeflected state of the platen 200 shown in FIG. 3A. In various examples, the platen 200 may be cooled to a temperature between −50° C. and −150° C. In a specific, non-limiting example, the platen 200 may exhibit a deflection of 22 ohms when cooled to a temperature of −100° C. The present disclosure is not limited in this respect. The smaller gap 220 and closer proximity of the electrode 216 to the wafer 218 facilitated by the deflected platen 200 provides a stronger electrostatic force acting on the wafer 218 compared to the electrostatic force applied by the undeflected platen 200 shown in FIG. 3A , resulting in better electrostatic coupling between the platen 200 and the wafer 218.

[0028]

[0035] The degree of deflection in the heated platen 200 depends on many factors, including, but not limited to, the CTE of the first layer 212 and the second layer 214, the amount of cooling applied to the first layer 212 and the second layer 214, the diameter of the first layer 212 and the second layer 214, and the thickness of the first layer 212 and the second layer 214. In a non-limiting embodiment, the first layer 212 may be 4 millimeters thick and the second layer 214 may be 4 millimeters thick. In another non-limiting embodiment, the first layer 212 may be 6 millimeters thick and the second layer 214 may be 4 millimeters thick. In another non-limiting embodiment, the first layer 212 may be 8 millimeters thick and the second layer 214 may be 4 millimeters thick. The present disclosure is not limited in this respect, and the thicknesses of the first layer 212 and the second layer 214 may vary from those described above.

[0029]

[0036] In various embodiments, the deflection stress of the platen 200 during cooling may be greater than the yield strength of the material of the first layer 212 and / or the yield strength of the material of the second layer 214. Thus, if the platen 200 is allowed to warm to room temperature, the platen 200 may remain in a convexly deflected state, as shown in FIG. 3C . If the platen 200 deflects beyond a desired target amount during cooling (i.e., becomes more convex than desired), the platen 200 may be heated, such as by an external heat source (e.g., an oven). Because the CTE of the first layer 212 is greater than the CTE of the second layer 214, the heated first layer 212 expands more (i.e., more rapidly and / or to a greater extent) than the heated second layer 214, causing the platen 200 to deflect in the opposite direction (i.e., compared to when the platen 200 was cooled), which may reduce the convexity of the platen 200. The deflection stress of the platen 200 during heating may be greater than the yield strength of the material of the first layer 212 and / or greater than the yield strength of the material of the second layer 214, thereby resulting in plastic deformation. The above-described cooling and heating of the platen 200 may be repeated as necessary until a desired amount of deflection in the platen 200 is achieved. Thus, by varying the amount of cooling and heating applied to the first layer 212 and the second layer 214, the platen 200 may be controllably deflected to various degrees (e.g., 0 to 22 ohms) to conform to or approximate the contours of wafers with various degrees of deflection disposed thereon and provide an effective electrostatic clamp therebetween.

[0030]

[0037] Referring to Figure 4, a flow diagram illustrating an exemplary method for deflecting a platen according to the present disclosure is shown. This method will now be described in conjunction with the illustration of platen 200 shown in Figures 3A-3C.

[0031]

[0038] At block 300 of the exemplary method, a first layer 212 may be provided and may be formed from a material having a first CTE. At block 310 of the method, a second layer 214 may be provided and may be formed from a material having a second CTE, and the second layer 214 may be flat-bonded to the first layer 212, such as by epoxy or other suitable techniques as described above. The first CTE may be greater than the second CTE. In various embodiments, the first layer 212 may have a CTE of 6.0×10 -7 / ℃~8.0×10 -7 / °C, the second layer 214 may be formed from a material having a CTE in the range of 6.0×10 -7 / °C (e.g., 2.0 x 10 -7 / ℃~4.0×10 -7 / °C). Second layer 214 may have a plurality of electrodes 216 embedded therein. Electrodes 216 may be connected to a power source and may be positioned and configured to operate in the manner of conventional electrostatic clamping, as is well known to those skilled in the art.

[0032]

[0039] In block 320 of the exemplary method, the platen 200 can be rapidly and significantly cooled. In a non-limiting example, the platen 200 can be immersed in liquid nitrogen. The disclosure is not limited in this respect. Because the CTE of the first layer 212 is greater than the CTE of the second layer 214, the cooled first layer 212 can contract (i.e., more quickly and / or to a greater extent) than the cooled second layer 214, resulting in a convex deflection of the platen 200. Thus, the contour of the top surface of the platen 200 can more closely match the contour of the bottom surface of the wafer 218, reducing the size of the gap 220 therebetween compared to the undeflected state of the platen 200 shown in FIG. 3A.

[0033]

[0040] As will be appreciated by those skilled in the art, the above-described deflectable platens 10, 200 and related methods offer distinct advantages over conventional platens. For example, in the case of the above-described elastically deformable platen 10, the platen 10 can be dynamically deflected by the selective application of heat (e.g., via heat trace 15) to quickly and easily facilitate effective electrostatic clamping with wafers having various degrees of deflection. In the case of the above-described plastically deformable platen 200, the platen 200 can be deformed once to achieve a desired degree of deflection (via the application of cooling and heating), and then, in the absence of further cooling or heating, retains that deflected shape to facilitate effective electrostatic clamping with similarly deflected wafers.

[0034]

[0041] The present disclosure should not be limited in scope by the specific embodiments described herein. Indeed, various other embodiments of the present disclosure and modifications of the present disclosure, in addition to those described herein, will be apparent to those skilled in the art from the foregoing description and the accompanying drawings. Accordingly, such other embodiments and modifications are intended to be included within the scope of the present disclosure. Moreover, while the present disclosure has been described herein in the context of particular implementations in particular environments for particular purposes, those skilled in the art will recognize that its usefulness is not limited thereto. Embodiments of the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in light of the full scope and spirit of the present disclosure as described herein.

Claims

1. A deflectable platen, a first layer formed from a material having a first coefficient of thermal expansion (CTE); a second layer coupled to the first layer, the second layer having a second CTE greater than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; Equipped with the first CTE is 2.0×10 －７ / ℃ ~ 4.0 × 10 －７ / °C, and the second CTE is 6.0 x 10 －７ / ℃~8.0×10 －７ / °C.

2. 10. The deflectable platen of claim 1, wherein the first layer is formed from at least one of quartz, carbon, silicon, silicon nitride, silicon carbide, aluminum nitride, INVAR, KOVAR, molybdenum, tungsten, tantalum, and titanium.

3. The flexible platen of claim 1 , wherein the second layer is formed from at least one of ceramic, aluminum, silver, and copper.

4. A deflectable platen, a first layer formed from a material having a first coefficient of thermal expansion (CTE); a second layer coupled to the first layer, the second layer having a second CTE less than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; Equipped with the second CTE is 2.0×10 －７ / ℃ ~ 4.0 × 10 －７ / °C, and the first CTE is 6.0 x 10 －７ / ℃~8.0×10 －７ / °C.

5. 5. The deflectable platen of claim 4, wherein the second layer is formed from at least one of quartz, carbon, silicon, silicon nitride, silicon carbide, aluminum nitride, INVAR, KOVAR, molybdenum, tungsten, tantalum, and titanium.

6. The flexible platen of claim 4 , wherein the first layer is formed from at least one of ceramic, aluminum, silver, and copper.

7. The flexible platen of claim 1 , further comprising a heat trace disposed between the first layer and the second layer and adapted to controllably heat the first layer and the second layer.

8. The flexible platen of claim 7 , wherein the heat trace comprises at least one of a wire, a cable, a plate, and a tape connected to a power source.

9. A deflectable platen, a first layer formed of a material having a first coefficient of thermal expansion (CTE); a second layer coupled to the first layer, the second layer having a second CTE greater than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; a heat trace disposed between the first layer and the second layer and adapted to controllably heat the first layer and the second layer; Equipped with the first CTE is 2.0×10 －７ / ℃ ~ 4.0 × 10 －７ / °C, and the second CTE is 6.0 x 10 －７ / ℃~8.0×10 －７ / °C.

10. 1. A method of deflecting a platen, comprising: providing a first layer formed of a material having a first coefficient of thermal expansion (CTE); providing a second layer coupled to the first layer and having a second CTE greater than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; Including, the first CTE is 2.0×10 －７ / ℃ ~ 4.0 × 10 －７ / °C, and the second CTE is 6.0 x 10 －７ / ℃~8.0×10 －７ / °C, The method further comprises: heating the first layer and the second layer to a temperature in the range of 300°C to 600°C; cooling the first layer and the second layer to a temperature in the range of −50° C. to −150° C.; The method includes one of the following:

11. The method of claim 10 further comprising disposing a heat trace between the first layer and the second layer.

12. 11. The method of claim 10, further comprising activating a heat trace disposed between the first layer and the second layer to heat the first layer and the second layer.

13. 1. A method of deflecting a platen, comprising: providing a first layer formed of a material having a first coefficient of thermal expansion (CTE); providing a second layer coupled to the first layer and having a second CTE less than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; Including, the second CTE is 2.0×10 －７ / ℃ ~ 4.0 × 10 －７ / °C, and the first CTE is 6.0 x 10 －７ / ℃~8.0×10 －７ / °C, The method further comprises: heating the first layer and the second layer to a temperature in the range of 300°C to 600°C; cooling the first layer and the second layer to a temperature in the range of −50° C. to −150° C.; The method includes one of the following:

14. 1. A method of deflecting a platen, comprising: providing a first layer formed of a material having a first coefficient of thermal expansion (CTE); providing a second layer coupled to the first layer and having a second CTE less than the first CTE, the second layer including a plurality of electrodes embedded therein to facilitate electrostatic clamping of a wafer to the second layer; Including, The method further comprises: heating the first layer and the second layer to a temperature in the range of 300°C to 600°C; cooling the first layer and the second layer to a temperature in the range of −50° C. to −150° C.; and The method, wherein cooling the first layer and the second layer comprises at least partially immersing the first layer and the second layer in liquid nitrogen.

Images