KR20180028401A - Bolted wafer chuck thermal management systems and methods for wafer processing systems - Google Patents

Abstract

The workpiece holder includes first and second heating devices in thermal communication with the inner and outer portions of each of the puck, puck, and a heat sink in thermal communication with the puck. The first and second heating devices are independently controllable and the first and second heating devices are in thermal communication with the puck more heavily than the thermal communication between the puck and the heat sink. A method for controlling the temperature distribution of a workpiece includes flowing a heat exchange fluid through a heat sink to establish a reference temperature for the puck, Raising the temperatures of the radially inner and outer portions of the puck to first and second temperatures greater than a reference temperature by activating the second heating devices and placing the workpiece on a puck do.

Description

Bolted wafer chuck thermal management systems and methods for wafer processing systems

[0001] The present disclosure is broadly applicable to the field of processing equipment. More specifically, systems and methods are disclosed for providing spatially tailored processing for a workpiece.

[0002] Typically, integrated circuits and other semiconductor products are fabricated on the surfaces of substrates referred to as "wafers ". Occasionally, processing is performed on a group of wafers held in a carrier, but at other times processing and testing is performed on one wafer at a time. When single wafer processing or testing is performed, the wafer can be positioned on the wafer chuck. Other tasks may also be processed on similar chucks. The chucks can be temperature controlled to control the temperature of the workpiece for processing.

[0003] In an embodiment, the workpiece holder positions the workpiece for processing. The workpiece holder may include a substantially cylindrical puck, a first heating device disposed in thermal communication with the radially inner portion of the puck, a second heating device disposed in thermal communication with the radially outer portion of the puck, And a heat sink disposed therein. The first and second heating devices are independently controllable relative to each other and the first and second heating devices are each in thermal communication with the puck to a degree greater than the degree of thermal communication between the puck and the heat sink.

[0004] In an embodiment, a method for controlling the spatial temperature distribution of a workpiece includes providing a substantially cylindrical puck with a reference temperature by flowing a controlled temperature of heat exchange fluid through the channels of the heat sink in thermal communication with the puck ; Raising the temperature of the radially inner portion of the puck to a first temperature that is greater than the reference temperature by activating a first heating device disposed in thermal communication with the radially inner portion of the puck; Raising the temperature of the radially outer portion of the puck to a second temperature greater than the reference temperature by activating a second heating device disposed in thermal communication with the radially outer portion of the puck; And placing the workpiece on the puck.

[0005] In an embodiment, a work holder for positioning a workpiece for processing includes a substantially cylindrical puck characterized by a cylindrical axis and a substantially planar top surface. The puck defines two radial heat shields. The first row interrupter is characterized as a radial recess that intersects the bottom surface of the puck at a first radius and extends through at least a half of the thickness of the puck from the bottom surface. The second row intercept is characterized as a radial recess that intersects a top surface of the puck at a second radius greater than the first radius and extends through at least one half of the thickness of the puck from the top surface. The first and second heat shields define a boundary between the radially inner portion of the puck and the radially outer portion of the puck. The puck includes a first heating device embedded within the radially inner portion of the puck and a second heating device embedded within the radially outer portion of the puck. The workpiece holder also includes a heat sink extending substantially below the bottom surface of the puck, the heat sink having a metal plate-channel for flowing heat exchange fluid through the channels to maintain a reference temperature for the puck, Are defined within the metal plate. The heat sink is mechanically and thermally mechanically and thermally coupled to the puck at attachment points that provide a degree of thermal communication between the heat sink and the puck that is less than the degree of thermal communication between each of the first and second heating devices and the puck. do.

[0006] FIG. 1 schematically illustrates the major elements of a processing system with a workpiece holder, according to an embodiment.
[0007] FIG. 2 is a schematic cross-sectional view illustrating exemplary configuration details of the work holder of FIG. 1.
[0008] FIG. 3 is a schematic cross-sectional view illustrating the integration of heat sinks and heaters with the inner and outer portions of the puck forming part of the work holder of FIG. 1, consistent with the embodiment;
[0009] FIG. 4 is a schematic cross-sectional view illustrating a portion of a wafer chuck, illustrating features of a heat sink, resistive heater, and puck consistent with the embodiments.
[0010] FIG. 5 schematically illustrates the lower side of a puck having cable heaters installed therein as inner and outer resistive heaters, consistent with the embodiment.
[0011] FIG. 6A is a detail view of a portion of the optional heat sink and puck of FIG. 4 near the fastener.
[0012] FIG. 6B schematically illustrates an embodiment of an uncompressed wave washer consistent with an embodiment.
[0013] FIG. 6C provides an elevated bottom plan view of the optional heat sink and puck illustrated in FIG. 6A.
[0014] FIG. 7 schematically illustrates a lift pin mechanism disposed within a thermal barrier, consistent with embodiments.
[0015] FIG. 8 schematically illustrates, in plan view, three lift pin arrangements in which lift pins are disposed within a thermal cutout, consistent with the embodiment;
[0016] FIG. 9 is a flow diagram of a method for processing a wafer or other workpiece consistent with an embodiment.
[0017] FIG. 10 is a flow diagram of a method including but not limited to one step of the method of FIG.
[0018] FIG. 11 is a flow diagram of a method including but not limited to other steps of the method of FIG.

[0019] The present disclosure may be understood by reference to the following detailed description taken in conjunction with the drawings set forth below, wherein like reference numerals are used in the various figures to refer to like components. It is noted that for purposes of clarity of illustration, certain elements in the figures may not be shown in scale. Numbers without parentheses refer to any such item (e.g., heaters 220-1 and 220-2), while numbers may be used after a dash to refer to specific instances of items (e.g., heaters 220-1 and 220-2) Heaters 220). In instances where multiple instances of an item are shown, only a portion of the instances may be labeled for clarity of illustration.

[0020] Figure 1 schematically illustrates the major elements of the wafer processing system 100. Although the system 100 is depicted as a single wafer, semiconductor wafer plasma processing system, it will be apparent to those skilled in the art that the techniques and principles herein are applicable to any type of wafer processing systems (e.g., Or semiconductors, and does not necessarily utilize the plasma for processing). The processing system 100 includes a housing 110 for a wafer interface 115, a user interface 120, a plasma processing unit 130, a controller 140, and one or more power supplies 150. do. The processing system 100 is supported by a variety of utilities that may include gas (s) 155, external power 170, vacuum 160, and optionally others. For clarity of illustration, the internal piping and electrical connections within the processing system 100 are not shown.

[0021] The processing system 100 may be configured to generate plasma at a first location and direct plasma and / or plasma products (e.g., ions, molecular fragments, energized species, etc.) to a second location where processing occurs Called indirect plasma processing system. 1, the plasma processing unit 130 includes a plasma source 132 for supplying plasma and / or plasma products for the process chamber 134. The process chamber 134 includes one or more work holders 135 and the wafer interface 115 is configured to hold the workpiece 50 to be held for processing (e.g., a semiconductor wafer, (Which may be a workpiece) on workpiece holders 135. When the workpiece 50 is a semiconductor wafer, the workpiece holder 135 is usually referred to as a wafer chuck. In operation, gas (s) 155 are introduced into the plasma source 132 and a radio frequency generator (RF generator) 165 supplies power to ignite the plasma within the plasma source 132 . Plasma and / or plasma products pass from the plasma source 132 through the diffuser plate 137 and into the process chamber 134 where the workpiece 50 is processed. In addition to or alternatively to the plasma from the plasma source 132, the plasma may also be ignited within the process chamber 134 for direct plasma processing of the workpiece 50.

[0022] The embodiments herein provide novel and useful functions for plasma processing systems. Semiconductor wafer size has increased while significant feature sizes have been decreasing over the years, so that more integrated circuits per integrated circuit - the integrated circuits have greater functionality - can be obtained. Processing smaller features while the wafers are larger requires significant improvements in processing uniformity. Usually, temperature control over wafers during processing is usually the key to uniform processing because chemical reaction rates are temperature sensitive.

[0023] In addition, some types of processing (e.g., processing from the center to the edge of the wafer) may have radial effects. Some types of process equipment can better control these effects than others, i. E., Some achieve high radial process uniformity, while others do not. It will be appreciated that embodiments of the present application will be more advantageous to be able to provide radial processing that can be tailored to compensate for processing where radial effects are advantageously controlled and that can not achieve such control. For example, consider the case where a layer is deposited on a wafer and then selectively etched, as is common in semiconductor processing. If the deposition step is known to deposit a thicker layer at the edge of the wafer than at the center of the wafer, the compensating etch step will advantageously provide a higher etch rate at the edge of the wafer than at the center of the wafer, The etched layer will be etched to be completed simultaneously on all parts of the wafer. Similarly, if the etch process is known to have a center-to-edge change, then the compensation deposition prior to the etch process can be adjusted to provide a corresponding change.

[0024] In such many cases of processing with radial effects, a compensation process may be provided by providing an apparent center-to-edge temperature change, which is usually because the temperature substantially affects the reaction rates of the processes.

[0025] Figure 2 is a schematic cross-section illustrating exemplary configuration details of the work holder 135 of Figure 1. 2, the workpiece holder 135 includes a substantially cylindrical puck 200 and is characterized by having a puck radius r1 in the radial direction R from the cylindrical axis Z. In one embodiment, do. In use, the workpiece 50 (e.g., a wafer) may be positioned on the puck 200 for processing. The bottom surface 204 of the puck 200 is taken to be the mid-bottom surface height of the puck 200; That is to say that the puck 200 can be positioned in the direction of the axis Z except for features such as edge rings or other protrusions 206 or indentations 208 that may be formed as attachment points for other hardware Is taken to be a plane defining the typical bottom surface height of the puck (200). Similarly, top surface 202 is taken to be a planar surface configured to receive workpiece 50, including grooves that can be formed on such planar surface (see FIG. 4, e.g., as vacuum channels) And / or other features that maintain work (50). All such protrusions, indents, grooves, rings, etc. do not impair the characteristics of the " substantially cylindrical "puck 200 in the context of this specification. The puck 200 may also be characterized as having a thickness t between the bottom surface 204 and the top surface 202, as shown. In certain embodiments, the puck radius rl is at least four times the puck thickness t, but this is not a requirement.

[0026] The puck 200, as shown, defines one or more radial heat shields 210. The heat shields 210 are radial recesses defined in the puck 200 that intersect at least one of the top surface 202 or the bottom surface 204 of the puck 200. The thermal cut-offs provide thermal resistance between the radially outer portion 214 and the radially inner portion 212 of the puck 200 to provide. This facilitates the apparent radial (e.g., mid-to-edge) thermal control of the radially inner and outer portions of the puck 200, which provides for precise thermal matching of the inner and outer portions, It is advantageous in terms of providing an intentional temperature change over the portions. The heat shields 210 may have a heat interception depth and a heat interception radius. Although the depth of the heat shields 210 may vary between embodiments, the depth of the heat shield generally exceeds one-half of the thickness t. The radial positioning of the thermal cut-offs 210 may also vary between embodiments, but the thermal cutout radius r2 is generally at least one-half of the puck radius r1, and in other embodiments, r2 may be 3/4, 4/5, 5/6, or more of the puck radius rl. Certain embodiments may use a single heat intercept 210, while other embodiments may use two heat intercepts 210 or more (as shown in FIG. 2). Although the boundary point between the radially inner portion 212 and the radially outer portion 214 is illustrated by the radial average position between the two thermal cut-off portions 210, in embodiments with a single thermal cut-off 210, The boundary point may be considered to be the radial center of the single row interceptor 210.

[0027] One way in which the heat shields as illustrated in FIG. 2 may be advantageously used is to apply radially applied heating and / or cooling to the inner portion 212 and the outer portion 214 of the puck 200 . 3 is a schematic cross-sectional view illustrating the integration of heat sinks and heaters with the inner and outer portions of the puck 200. FIG. For clarity of illustration, some mechanical details of the puck 200 are not shown in FIG. FIG. 3 illustrates a center channel 201 defined by optional heat sink 230 and puck 200. The central channel 201 is described with reference to FIG. The inner heaters 220-1 and the outer heaters 220-2 are disposed in thermal communication with the puck 200; The heaters 220 are shown buried in the puck 200, but this is not necessary. While it may be advantageous for the heaters 220 to be disposed over large portions of the puck 200, in embodiments, the distribution of the heaters 220 across the surface 204 may vary. The heat provided by the heaters 220 will substantially control the temperatures of the inner portion 212 and the outer portion 214 of the puck 200; Heat shields 210 assist in thermally isolating portions 212 and 214 from each other to improve the accuracy of thermal control thereof. The heaters 220 are typically resistive heaters, but other types of heaters (e.g., utilizing a forced gas or liquid) may be used.

[0028] Optional heat sink 230 may also be provided. The heat sink 230 may be controlled to provide a lower temperature than typical operating temperatures, for example, by flowing a heat exchange fluid through a heat sink to a controlled temperature, or by using a cooling device such as a Peltier cooler . If present, the heat sink 230 provides several advantages. One such advantage is that when there is no heat provided by the heaters 220, the reference temperature is provided by all parts of the puck 200. That is, even though the heaters 220 may provide heat, such heat will typically propagate through the entire puck 200 in all directions. The heat sink 230 provides the ability to cause all parts of the puck 200 to be at lower temperatures so that when the heater 220 is located in a particular part of the puck 200, Does not simply diffuse in all directions through the entire puck 200 but heats a portion of the puck 200 and the heat from the heater 200 at such a portion of the puck is heated by a heat sink 230 ). ≪ / RTI > 3, the attachment points 222 may not resemble those shown in FIG. 3; FIGS. 6A, 6B, < RTI ID = 0.0 > , And 6c). The puck 200 may be thermally and / or mechanically coupled. The attachment points 222 are advantageously multiple and spread evenly around the surface 204 of the puck 200. The attachment points 222 provide substantially all of the thermal communication between the heat sink 230 and the puck 200 and provide a plurality of evenly spaced attachment points 222 such that the provided reference temperature can be uniformly applied. Spreading arrangement is provided. For example, a puck 200 of at least 10 inches in diameter may have at least 20 or more attachment points, and a puck 200 of at least 12 inches in diameter may have at least 30 or more attachment points have.

[0029] A related advantage is that heat sinks 230 (e.g., heat sinks) can be used to reduce heat dissipation so that adjacent portions of the puck 200 respond with relatively rapid thermal degradation when the temperature settings of the heaters 220 (e.g., electrical currents passing through the resistive wires) ) Can provide rapid heat sinking capability. This may be accomplished, for example, by loading the workpiece 50 on the puck 200, providing heat through the heaters 220, and heating the workpiece 50 such that the processing can begin quickly to maximize system throughput. The present invention provides an advantage of achieving rapid stabilization of the < / RTI > If there is no thermal communication to allow some heat to dissipate into the heat sink 230, the temperatures reached by the portions of the puck 200 will only decrease as fast as other heat dissipation paths allow.

[0030] The heaters 220 and heat sink 230 are typically arranged so that they are in thermal communication with the puck 200; For example, the heaters 220 may be in direct thermal communication with the puck 200 while the heat sink is indirectly in thermal communication with the puck 200. That is, the heaters 220 are typically positioned for a high degree of thermal coupling with the puck 200, and the heat sink 230 is positioned for a lesser degree of thermal coupling with the puck 200 At least less than the heaters 220, thermal coupling with the puck 200). The heaters 220 also have sufficient heat generation capability that the heat applied by the heaters 220 can overwhelm the thermal coupling of the puck 200 and the heat sink 230, The heater 220 can raise the temperature of the inner portion 212 and the outer portion 214 of the puck 200 even when a portion of the heat generated by the heaters 220 dissipates through the heat sink 230 . Thus, the heat provided by the heaters 220 may be dissipated through the heat sink 230, but not immediately dissipated. The degree and arrangement of thermal coupling between the puck 200, the heaters 220, and the heat sink 230 is such that the temperature uniformity in the inner portion 212 and the outer portion 214, respectively, , Rapidity of thermal stabilization, manufacturing complexity and cost, and overall energy consumption, in accordance with the principles set forth herein.

[0031] Another advantage of the heat sink 230 is that it limits the heat generated by the heaters 220 to the vicinity of the puck 200. [ That is, heat sink 230 may provide a thermal limit for such components to protect adjacent system components from the high temperatures generated in puck 200. This can improve the mechanical stability of the system and / or prevent damage to temperature sensitive components.

[0032] The heaters 220 and the heat sink 230 may be implemented in a variety of ways. In embodiments, the heaters 220 may be provided with cable-type heating elements that are integrated with the puck 200 and then (optionally) integrated with the heat sink 230 to form a wafer chuck assembly . Embodiments that are designed, assembled and operated as disclosed herein allow for explicit temperature control of the edge regions for the central regions of the workpiece (e.g., wafer), and are typically used to provide clear, Facilitates processing using center-to-edge temperature control.

[0033] 4 is a schematic cross-sectional view of a portion of a wafer chuck illustrating puck 200, a resistive heater serving as heater 220-1, and features of heat sink 230. [ Figure 4 shows a portion of the wafer chuck near the cylindrical axis Z of the wafer chuck and is not shown to scale for the sake of example clarity of smaller features. The puck 200 is typically formed of an aluminum alloy, such as the well-known "6061" alloy type. The puck 200 is connected on the upper surface 202 of the puck 200 and defines surface grooves or channels 205 that are connected to the center channel 201 centered about the axis Z . It will be appreciated that atmospheric pressure (or low pressure vapor deposition systems, such as about 10-20 Torr, or gas pressures of relatively high pressure plasmas) can be applied to the puck 200 A vacuum can be applied to the central channel 201 to reduce the pressure within the channels 205 to provide good thermal communication between the puck 200 and the workpiece 50. [

[0034] Although the inner resistive heater 220-1 is illustrated in FIG. 4, it should be understood that the following description and examples of the inner resistive heater 220-1 apply equally to the outer resistive heater 220-2. The resistive heater 220-1 includes a cable heater 264 that is wound in a spiral or other pattern within the puck 200. The cable heater 264 is assembled within the puck 200 by placing a cable heater 264 within the grooves of the puck 200 and capping the grooves (see FIG. 5). After assembly of the cable heaters 264 (and the second cable heater as the outer resistive heater 220-2) as the inner resistive heater 220-1, the puck 200 is heated by the fasteners 270, (230). The regions of both the puck 200 and the heat sink 230, which provide attachment points to the fasteners 270, can be used to secure the fasteners 270, as discussed in further detail below (see FIGS. 6A, 6B, Is arranged to manage the heat transfer characteristics between the puck 200 and the heat sink 230 around the puck 200 and the heat sink 230.

[0035] FIG. 5 schematically illustrates the lower side of the puck 200-1 having cable heaters 264-1 and 264-2 respectively installed therein as inner and outer resistive heaters. The heat shield 210 is a recess defined in the bottom surface 204 of the puck 200-1 and forms a radial boundary between the inner portion 212 and the outer portion 214 of the puck 200 (See Figs. 2 and 3). Cable heater 264-1 extends from connector 262-1 along a generally helical path disposed for uniform heat transfer to all regions of inner portion 212. [ The heater cap 266-1 is illustrated as a shaded portion of the helical path; Heater cap 266-1 is coupled in place after cable heater 264-1 is in place. In an embodiment, the heater cap 266-1 is a pre-formed fillet in the shape of a groove in which the cable heater 264-1 is installed and is secured in place. The heater cap 266-1 can be welded in place using, for example, electron beam welding, but can also be secured using adhesives or fillers (e.g., epoxy). The fillets are preferably welded in place along at least a portion of the arc length of the cable heater, but need not be welded along the entire arc length thereof (e.g., in the overlying structures, such as cable heater 264-2) To avoid damage to the parts, the parts may not be welded). In an embodiment, the heater cap 266-1 is welded in place using electron beam welding. The cold-to-hot transition point 265-1 includes a cable heater 264-1 extending from the connector 262-1 and hidden under the heater cap 266-1, Lt; / RTI > are connected to the resistive materials in the cable heater 264-1. Therefore, almost no heat is generated between the connector 262-1 and the transition point 265-1, but a uniform amount of heat per unit length passes through the transition point 265-1 to the cable heater 264-1, Lt; / RTI > The cable heater 264-2 extends from the connector 262-2 radially outwardly from the central region of the puck 200 first (connections are formed through the shaft of the wafer chuck in the central region) Lt; RTI ID = 0.0 > 214 < / RTI > The heater cap 266-2 is illustrated as the shaded portion of the helical path; Heater cap 266-2 is coupled in place after cable heater 264-2 is put in place. In an embodiment, the heater cap 266-2 is a pre-formed fillet in the shape of a groove provided with a cable heater 264-2 and is welded in place using electron beam welding. The fillet forming heater cap 266-2, such as heater cap 266-1, is preferably welded in place along at least a portion of its arc length, but need not be welded along its entire arc length . The cold-to-hot transition point 265-2 is formed by the conductive wires of the cable heater 264-2 extending from the connector 262-2 and hidden under the heater cap 266-2 to the cable heater 264- 2). ≪ / RTI > Therefore, almost no heat is generated between the connector 262-2 and the transition point 265-2, but a uniform amount of heat per unit length passes through the transition point 265-2 to the cable heater 264-2, Lt; / RTI > A set of protrusions 268 is also illustrated in Fig. The protrusions 268 are protrusions out of the plane of the view from the bottom surface 204 (e.g., such that the protrusions face the heat sink 230, see FIG. 3). The protrusions 268 form locations for the attachment points 222 and cooperate with the fasteners 270 of Figure 4 and are discussed in more detail below with respect to Figures 6a and 6b.

[0036] 6A is a detail view of a portion of optional heat sink 230 and puck 200 as shown in FIG. 4 in the vicinity of fastener 270. FIG. The puck 200 includes a cable heater 264 sealed within the puck 200 with a heater cap 266, as discussed above with respect to FIG. The heat sink 230 and the puck 200 may be positioned between the puck 200 and the heaters 220 while the optional heat sink 230 may provide a reference temperature to the puck 200, It is desirable to arrange for a lesser degree of thermal communication. The attachment points that allow for thermal communication between the heat sink 230 and the puck 200 are advantageously arranged to manage the heat transfer characteristics between the heat sink 230 and the puck 200. [ For example, the puck 200 and heat sink 230 may be manufactured such that there is a lateral gap 276 between the protrusion 268 and the heat sink 230, as shown. That is, the thickness of the heat sink 230 is reduced in the thinned region 235 near the protrusion 268, and the lateral extent of the thinned region 235 is larger than the lateral extent of the protrusion 268, A lateral gap 276 is formed between the entire thickness portion of the heat sink 268 and the heat sink 230. The heat sink 230 defines an opening for the fastener 270 to pass therethrough and the protrusion 268 defines an inner void 275 and a portion of the inner void is defined by the fastener 270, And may be internally threaded to be coupled. However, the void 275 may be longer than the length of the fastener 270 to limit heat transfer from the puck 200 through the protrusion 268, for example, as shown in FIG. 6A. The physical attachment point of the puck 200 to the heat sink 230 includes the protrusion 268, the fastener 270, and the pair of washers 272. The major heat transfer paths near the fastener 270 are shown by the solid arrowed waves arrows 278 in Figures 6a and 6b while the minor (e.g., radiative) Wave arrows 279 are shown. The void 231 is discussed below with respect to Figure 6C.

[0037] FIG. 6B schematically illustrates an embodiment of a wave washer 272 in an uncompressed state. While it is possible to utilize flat washers in certain embodiments, corrugated washers are advantageous in other embodiments. The washer 272 in the azimuthally wavy form does not overly constrain the puck 200 or the heat sink 230 relative to each other but allows the puck 200 at the plurality of points to be coupled to the heat sink 230 and the couple It is advantageous in that it can be linked. More than three attachment points between the puck 200 and the heat sink 230 are defined by the protrusions 268 and 268 of the puck 200, Forms an overconstrained system that imposes very strict mechanical tolerances on the planarity of the attachment points between the heat sinks 230. [ The use of corrugated washer 272 is advantageous because the washer 272 will provide mechanical coupling over the compression range rather than requiring the attachment point of each component to lie along a perfectly flat surface, Allowing for loose flatness tolerances. Likewise, the compression extent of corrugated washer 272 permits local thermal expansion effects of puck 200 and / or heat sink 230. In certain embodiments, the wave washer 272 has an uncompressed thickness 273 that is at least twice the compressed thickness 274; In other embodiments, the wave washer 272 has an uncompressed thickness 273 that is at least five times the compressed thickness 274. Although the washer 272 is shown in FIG. 6A as a flat cross-sectional profile for the sake of clarity, as the present disclosure is read and understood, the fastener 270 is not to be tightened to the point where it completely flattens the wave washer 272 And thus it will be appreciated that some waveforms will be present in the instances, albeit not much of the waveform washer 272 as installed. The wave washer 272 is also positioned such that heat is transferred from the protrusion 268 to a local peak at which the washer 272 contacts the protrusion 268 and then into the washer 272 The thermal contact between the protrusion 268 and the heat sink 230 is reduced by forcing the washer 272 to pass through a local trough in contact with the heat sink 230. [ The washers 272 may be formed of, for example, beryllium copper. Certain embodiments utilize two washers 272, one on each side of the heat sink 230, as shown, while the other embodiments typically use the protrusions 268 and the heat sink 230, Only a single washer 272 is used.

[0038] 6C provides a bottom plan view looking upward in the vicinity of the fastener 270. FIG. In Fig. 6C, the broken lines 6A-6A show the cross-sectional plane shown in Fig. 6A. The heat sink 230 forms one or more voids 231 in the thinned region 235 near the fastener 270. The voids 231 further reduce the thermal communication between the puck 200 and the heat sink 230. The arrangement and number of voids 231 of the heat sink 230 shown in Fig. 6C are not essential; It will be appreciated that as read and understood in this disclosure, voids 231 may be modified in size, number, and arrangement aspects to adjust the thermal coupling characteristics between heat sink 230 and puck 200 will be. For example, thermal coupling between the heat sink 230 and the puck 200 may be accomplished by providing a plurality of pucks 200 with respect to the illustrated voids 231 to extend the thermal path between the protrusions 268 and the body of the heat sink 230 By providing a second set of voids 231 radially outward from the voids 231, as shown in Figure 6C, by staggering the set of arrangements of the first set 231, . Figure 6C also shows that the outer edge of the thinned region 235 coincides with the outer edges of the voids 231, but this is not always necessary. Certain embodiments may have voids 231 that are well within the edges of the thinned region 235 or that extend partially into the heat sink 230 outside of the thinned region 235. Likewise, wall thicknesses and placement of protrusions 268 can be modified to achieve higher or lower thermal conduction between heat sink 230 and puck 200.

[0039] An additional advantage of providing at least one heat intercepting portion 210 that intersects the top surface of the puck 200 is that the mechanical features are not at least thermally deformed on the surface of the puck 200, And can be partially disposed within the heat block. For example, wafer chucks typically lift the wafer from the chuck to a small distance to facilitate access by wafer handling tools (typically using a paddle, or other device inserted between the wafer and the chuck after the wafer has been raised) To provide lift pins that can be used to actuate the lift pins. However, the lift pins typically retreat into the holes of the chuck, and such holes and lift pin structures may affect the wafer temperature locally during processing. When the thermal cutter crosses the top surface of the puck 200, there is already a position where such a mechanism is deployed without introducing thermal deformities.

[0040] FIG. 7 schematically illustrates a portion of a wafer chuck having a lift pin mechanism 300 that controls lift pins 310, disposed within thermal shut-off portion 210. Portions of the heaters 220 and optional heat sink 230 are also shown. The cross-sectional plane illustrated in FIG. 7 passes through the center of the mechanism 300 so that the components of the mechanism 300 are in the lower portion of one thermal cut-off 210. In and out of the plane shown, the puck 200, the heat shield 210, and the heat sink 230 may have profiles such as those shown in Figures 3 and 4, whereby the mechanism 300 is positioned The heat interrupter 210 will continue through the puck 200 along its arc (see FIG. 8). In addition, the lift pin mechanism 300 is limited to a relatively small azimuth angle with respect to the center axis of the puck 200 (again, see FIG. 8). 7, the bottom surface of the puck 200 will be continuous with the bottom surface 204 along the same plane as shown in Fig. 7, The heat sink 230 will be continuous below the puck 200. The small size of the lift pin mechanism 300 limits thermal drift of the puck 200 in the region of the lift pin mechanism 300. FIG. 7 illustrates a lift pin 310 in a retracted position that does not create an anomaly on the surface of the puck 200.

[0041] 8 schematically illustrates, in plan view, three lift pin arrangements in which the lift pins 310 are disposed within the thermal cut-off portion 210. As shown in FIG. 8 is not shown in full scale, and in particular, the thermal shut-off portion 210 has been exaggerated so that the lift pin mechanisms 300 and the lift pins 310 are clearly visible. The lift pins 310 do not create a spatial thermal malformation during processing because the lift pins 310 are well retracted into the thermal cut-off 210 below the average surface of the puck 200, (E.g., specific integrated circuits located at corresponding locations on the semiconductor wafer) that are processed at locations on the workpiece undergo processing that is consistent with processing elsewhere on the workpiece.

[0042] FIG. 9 is a flow diagram of a method 400 for processing a wafer or other workpiece (hereinafter simply referred to as a "workpiece wafer" for purposes of understanding, with concepts understood to be applicable to workpieces other than wafers). The method 400 may be uniquely enabled by the thermal management device described in connection with FIGS. 2-8, which may be used to provide explicit center-to-edge thermal control, Thermal control, as a result, allows for clear central-to-edge process control. The first step 420 of the method 400 processes the product wafer using a first center-to-edge process variation. The second step 440 of the method 400 processes the product wafer using a second center-to-edge process variation that compensates for the first center-to-edge variation. Typically, one or the other of 420 or 440 may be performed in a device or in a process environment that unintentionally or uncontrollably generates an associated central-to-edge process change (hereinafter "uncontrolled change") But this is not necessary. Also, typically, the other is performed in equipment as described herein, whereby heat management techniques that allow the center and edge portions of the product wafer to be explicitly controlled to provide a corresponding inverse process variation (Hereinafter referred to as "controlled change") is introduced through the center-to-edge process changes. However, uncontrolled and controlled changes can occur in any order. That is, 420 may introduce uncontrolled or controlled changes, and 440 may introduce another of uncontrolled and controlled changes. 10 and 11 provide additional guidance to those skilled in the art to enable the useful execution of method 400.

[0043] FIG. 10 is a flow diagram of method 401 including but not limited to step 420 of method 400. Although all of 410-418 and 422 shown in FIG. 10 are considered optional, in embodiments, it may be useful when executing method 400 to achieve useful wafer processing results.

[0044] Step 410 sets the equipment characteristics associated with the first center-to-edge process change to be generated at 420. For example, if 420 is expected to introduce a controlled change, 410 may entail providing equipment parameters such as heater settings that will provide a controlled center-to-edge temperature change. Equipment as described herein in Figures 2-8 is useful for providing controlled center-to-edge temperature variations. Step 412 measures the equipment characteristics associated with the first center-to-edge process change. Process knowledge about whether certain equipment settings or measured equipment characteristics have succeeded in generating (or at least providing a stable process change) a known central-to-edge process change . ≪ / RTI > With this process knowledge in mind, if the measured device characteristics at 412 are likely to be improved, the method 401 may optionally return from 412 to 410 to adjust the device characteristics. Step 414 processes one or more test wafers that accept a first central-to-edge process change. Step 416 measures one or more of the characteristics of the first center-to-edge process variation on the test wafer (s) processed in step 414. The method 401 may optionally return from 416 to 410 to adjust the machine characteristics taking into account the center-to-edge process characteristics measured at 416. [ Any test wafers processed at 414 may optionally be stored at 418 for testing in a second process (e.g., a process to be executed at 440 thereafter). Also, 414 may be performed in parallel with 420. That is, when the process equipment is properly configured, the test wafers can be processed at the same time as the product wafers (e.g., the first process includes immersing the cassettes of wafers in a liquid bath, batch "process, such as processing a set of wafers in a deposition chamber, a furnace, or a set of wafers in a deposition chamber.

[0045] Step 420 processes the product wafer using a first center-to-edge process variation. As further described below, step 422 may be used for equipment process control purposes, for correlating the yield or performance of the product wafer, and / or correlating the information associated with step 440 To produce data for use, one or more first center-to-edge characteristics on the product wafer are measured.

[0046] FIG. 11 is a flow diagram of method 402 including but not limited to step 440 of method 400. Although all of 430-436 and 442 shown in FIG. 11 are considered optional, in embodiments, it may be useful when executing the method 400 to achieve useful wafer processing results.

[0047] Step 430 sets the equipment characteristics associated with the second center-to-edge process change to be generated in step 440. [ For example, if 440 is expected to introduce a controlled change, 430 may entail providing equipment parameters such as heater settings that will provide a controlled center-to-edge temperature change. Equipment as described herein in Figures 2-8 is useful for providing controlled center-to-edge temperature variations. Step 432 measures equipment characteristics associated with a second central-to-edge process change. In view of the process knowledge, as discussed above, the method 402 may optionally return from 432 to 430 to adjust the machine characteristics taking into account the machine characteristics measured at 432. [ Step 434 processes one or more test wafers that have accepted a second central-to-edge process change; The test wafer (s) processed at 434 may include one or more test wafers stored at the first process stage at 418 in the foregoing description. Step 436 measures one or more of the characteristics of the second center-to-edge process variation on the test wafer (s) processed at 434. In view of the previously learned process knowledge, the method 402 may optionally return from 436 to 430 to adjust the machine characteristics taking into account the mid-to-edge process characteristics measured at 436. [

[0048] Step 440 processes the product wafer using a second center-to-edge process variation. Further, although not shown in method 402, additional test wafers may be processed in parallel with the product wafer. As described above, step 442 may be used for equipment process control purposes, for correlating the yield or performance of the product wafer, and / or for correlating information related to step 420 To produce the data, one or more first center-to-edge characteristics on the product wafer are measured. Such measurements may also be performed on any test wafer processed in parallel with the product wafer, but in any case 442 will generally not further alter any conditions present on the product wafer. That is, the results of 420 and 440 will be fixed to the product wafer at the conclusion of 440 regardless of any additional testing being performed.

[0049] Having described several embodiments, those skilled in the art will appreciate that various changes, alternative constructions, and equivalents may be resorted to without departing from the spirit of the invention. In addition, many well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Therefore, the above description should not be taken as limiting the scope of the present invention.

[0050] Plasma processing of workpieces other than wafers may also benefit from improved processing uniformity and are contemplated within the scope of this disclosure. Thus, characterization of chucks herein as "wafer chucks " for holding" wafers " should be understood as equivalent to chucks for holding any kind of workpieces, and similarly "wafer processing systems" Processing systems. ≪ / RTI >

[0051] Given a range of numerical values, the intervening value between the upper and lower bounds of such a numerical range, unless expressly specified otherwise in the context, (to the tenth) is also interpreted as being specifically described. Each smaller range of between any stated value or intervening value within the stated range and any other stated value or intervening value within the stated range is included. The upper and lower limits of these smaller ranges may be independently included or excluded from the range and any of the two limits may be included in smaller ranges or none of them, The scope is also included in the invention, subject to any specifically excluded limit within the stated range. Where the stated ranges include one or both of the limits, ranges excluding either or both of those included limits are also included.

[0052] As used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "process" includes a plurality of such processes, and reference to "electrode" includes reference to one or more electrodes and equivalents thereof known to those skilled in the art, to be. It is also to be understood that the words "comprise", "comprising", "include", "including", and "includes" Are intended to specify the presence of integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Claims (15)

A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising:
A substantially cylindrical puck;
A first heating device disposed in thermal communication with a radially inner portion of the puck;
A second heating device disposed in thermal communication with a radially outer portion of the puck, the first and second heating devices being independently controllable relative to each other; And
And a heat sink disposed in thermal communication with the puck,
Each of the first and second heating devices being in thermal communication with the puck to a degree greater than a degree of thermal communication between the puck and the heat sink,
Work holders for positioning workpieces for processing. The method according to claim 1,
Wherein at least one of the first heating device and the second heating device includes a cable heater disposed in a groove defined within a bottom surface of the puck,
And a heater cap disposed within the groove for holding the cable heater in place, the heater cap being secured to the puck along at least a portion of the arc length of the cable heater,
Work holders for positioning workpieces for processing. The method according to claim 1,
The puck being mechanically and thermally coupled to the heat sink at a plurality of attachment points, wherein in at least one of the attachment points,
The puck forming a protrusion that faces the heat sink;
The heat sink forming an opening; And
The fastener is coupled through the opening and within the projection;
And wherein the plurality of attachment points provide substantially all of the thermal communication between the puck and the heat sink,
Work holders for positioning workpieces for processing. The method of claim 3,
Wherein the puck is at least 12 inches in diameter and the plurality of attachment points comprises at least 30 attachment points.
Work holders for positioning workpieces for processing. The method of claim 3,
Wherein at least one of the attachment points comprises:
Said protrusion defining a first lateral extent, and
Wherein the heat sink defines a thinned portion that is reduced in thickness around the aperture and wherein the thinned portion has a second lateral extent that is greater than the first lateral extent, There is a lateral gap between protrusions,
Work holders for positioning workpieces for processing. 6. The method of claim 5,
Wherein the heat sink defines one or more voids adjacent the opening and within the thinned portion to limit heat transfer from the puck to the heat sink,
Work holders for positioning workpieces for processing. The method of claim 3,
Further comprising a wave washer disposed about the fastener between the heat sink and the projection, the wave washer having an uncompressed total thickness of at least twice the compressive thickness of the corrugated washer,
Work holders for positioning workpieces for processing. The method according to claim 1,
Wherein the heat sink comprises a metal plate defining one or more fluid channels and wherein the heat exchange fluid flows through the one or more fluid channels to define a reference temperature for the heat sink,
Work holders for positioning workpieces for processing. The method according to claim 1,
The puck being characterized by a cylindrical axis, a puck radius about the cylindrical axis, and a puck thickness,
At least the top surface of the substantially cylindrical puck is substantially planar, and
The substantially cylindrical puck defines one or more radial thermal cut-off portions between the radially inner portion and the radially outer portion of the puck,
Each thermal cut-off is characterized by a radial recess that intersects at least one of a top surface and a bottom surface of the substantially cylindrical puck,
A depth of a thermal cutoff portion extending from a top surface or bottom surface of the puck through at least one half of the thickness of the puck and a depth of a thermal cutoff portion disposed symmetrically about the cylindrical axis, Characterized by:
Work holders for positioning workpieces for processing. A method for controlling the spatial temperature distribution of a workpiece,
Providing a controlled temperature of heat exchange fluid through channels of a heat sink in thermal communication with the puck to thereby provide a reference temperature to the substantially cylindrical puck;
Raising the temperature of the radially inner portion of the puck to a first temperature that is greater than the reference temperature by activating a first heating device disposed in thermal communication with the radially inner portion of the puck;
Raising the temperature of the radially outer portion of the puck to a second temperature greater than the reference temperature by activating a second heating device disposed in thermal communication with the radially outer portion of the puck; And
And placing the workpiece on the puck.
A method for controlling the spatial temperature distribution of a workpiece. 11. The method of claim 10,
Wherein providing the reference temperature to the substantially cylindrical puck further comprises coupling the heat sink to the substantially cylindrical puck at a plurality of attachment points; And
Wherein providing the reference temperature to the substantially cylindrical puck comprises:
To increase the thermal resistance between the heat sink and the puck,
Providing the heat sink with voids adjacent each of the attachment points; And
Further comprising positioning at least one of the wave washers between the heat sink and the substantially cylindrical puck.
A method for controlling the spatial temperature distribution of a workpiece. 11. The method of claim 10,
Raising the temperature of the radially inner portion of the puck and raising the temperature of the radially outer portion of the puck comprises flowing current through the cable heater,
A method for controlling the spatial temperature distribution of a workpiece. 11. The method of claim 10,
Providing a thermal resistance between the radially inner portion of the puck and the radially outer portion of the puck by providing one or more heat shields between the radially inner portion and the radially outer portion within the puck Further comprising:
Each of the heat shields defining a radial recess that intersects at least one of a top surface and a bottom surface of the puck;
The radial recess being characterized by a depth in excess of half the thickness of the puck,
A method for controlling the spatial temperature distribution of a workpiece. 14. The method of claim 13,
Providing one or more heat shields between the radially inner portion and the radially outer portion within the puck includes providing a radial recess that intersects the top surface of the puck; And
Wherein disposing the workpiece on the puck includes retracting one or more lift pins supporting the workpiece into the radial recesses intersecting the top surface of the puck,
A method for controlling the spatial temperature distribution of a workpiece. A work holder for positioning a workpiece for processing,
Wherein the workpiece holder comprises a substantially cylindrical puck characterized by a cylindrical axis and a substantially planar top surface,
The puck defines two radial heat shields,
The first of the heat shields is characterized by a radial recess that intersects the bottom surface of the puck at a first radius and extends through at least one half of the thickness of the puck from the bottom surface ,
And a second heat intercepting portion of the heat intercepting portion intersects the top surface of the puck at a second radius greater than the first radius and extends radially from the top surface through at least a half of the thickness of the puck, Characterized by a recess,
The first and second heat interrupts define a boundary between the radially inner portion of the puck and the radially outer portion of the puck,
The puck,
A first heating device embedded within the radially inner portion of the puck, and
A second heating device embedded within the radially outer portion of the puck,
Wherein the workpiece holder further comprises a heat sink extending substantially below the bottom surface of the puck, the heat sink comprising a plurality of heat sinks configured to flow heat exchange fluid through the channels to maintain a reference temperature for the puck A metal plate, wherein the channels are defined within the metal plate,
The heat sink is mechanically connected at a plurality of attachment points providing a degree of thermal communication between the heat sink and the puck less than the degree of thermal communication between each of the first and second heating devices and the puck And thermally coupled to the puck,
Work holders for positioning workpieces for processing.

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