KR102652012B1 - Thermal management systems and methods for wafer processing systems - Google Patents

Abstract

The workpiece holder includes a puck having a cylindrical axis, a radius about the cylindrical axis, and a thickness. At least a top surface of the puck is substantially planar, and the puck defines one or more thermal shields. Each thermal break is a radial recess that intersects at least one of the top and bottom surfaces of the cylindrical puck. The radial recess has a thermal break depth that extends through at least half the puck thickness, and a thermal break radius that is at least half the puck radius. A method of processing a wafer includes processing the wafer with a first process that provides a first center-to-edge process variation, and thereafter processing the wafer with a second process that substantially compensates for the first center-to-edge process variation. and processing the wafer with a second process that provides a center-to-edge process variation.

Description

Thermal management systems and methods for wafer processing systems

[0001] The present disclosure has wide application in 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 surface of substrates called “wafers.” Sometimes, processing is performed on a group of wafers held on a carrier, while other times processing and testing is performed on one wafer at a time. When single wafer processing or testing is performed, the wafer may be positioned on a wafer chuck. Other workpieces may also be processed on similar chucks. The chucks may be temperature controlled to control the temperature of the workpiece for processing.

[0003] In an embodiment, a workpiece holder positions a workpiece for processing. The workpiece holder includes a substantially cylindrical puck characterized by a cylindrical axis, a puck radius about the cylindrical axis, and a puck thickness. The puck radius is at least four times the puck thickness, at least a top surface of the cylindrical puck is substantially planar, and the cylindrical puck defines one or more radial thermal breaks. Each thermal break is characterized by a radial recess that intersects at least one of the top and bottom surfaces of the cylindrical puck. The radial recess has a thermal break depth extending from the bottom or top surface of the puck through at least half the puck thickness, and a heat break radius disposed symmetrically about the cylindrical axis and being at least half the puck radius. It is characterized by

[0004] In one embodiment, a method of processing a wafer includes processing the wafer with a first process that provides a first center-to-edge process variation, and thereafter , processing the wafer with a second process providing a second center-to-edge process variation. The second center-to-edge process change substantially compensates for the first center-to-edge process change.

[0005] In an embodiment, a workpiece holder positions a workpiece for processing. The workpiece holder includes a substantially cylindrical puck characterized by a cylindrical axis and a substantially planar top surface. The cylindrical puck defines two radial thermal breaks. The first of the thermal breaks is characterized by a radial recess that intersects the cylindrical bottom surface of the puck at a first radius and extends from the bottom surface through at least half the thickness of the puck. A second one of the thermal breaks is characterized as a radial recess that intersects the top surface at a second radius greater than the first radius and extends from the top surface through at least half the thickness of the puck. The heat sink extends substantially below the bottom surface of the puck and includes a metal plate that flows heat exchange fluid through channels, the channels being defined within the metal plate, to maintain a reference temperature for the puck. . A first heating device is disposed between the heat sink and the puck. The first heating device is in thermal communication with the bottom surface of the puck and with the heat sink within a first radius. A second heating device is disposed between the heat sink and the puck. The second heating device is in thermal communication, outside the second radius, with the bottom surface of the puck and with the heat sink.

[0006] Figure 1 schematically illustrates the main elements of a processing system with a workpiece holder, according to an embodiment.
[0007] Figure 2 is a schematic cross-sectional view illustrating exemplary construction details of the workpiece holder of Figure 1;
[0008] Figure 3 is a schematic cross-sectional view illustrating the application of heat sinks and heaters to the inner and outer portions of the puck forming part of the workpiece holder of Figure 1, consistent with an embodiment.
[0009] Figure 4 is a schematic cross-sectional view illustrating features of a heat sink, resistive heater, and puck, consistent with an embodiment.
[0010] Figure 5 schematically illustrates the layout of heater traces in the inner resistive heater of Figure 4, consistent with an embodiment.
[0011] Figure 6 schematically illustrates a lift pin mechanism disposed within a thermal shield, consistent with an embodiment.
[0012] Figure 7 schematically illustrates, in top view, an arrangement of three lift fins with the lift fins disposed within a thermal shield, consistent with an embodiment.
[0013] Figure 8 is a flow diagram of a method for processing a wafer or other workpiece, consistent with an embodiment.
[0014] Figure 9 is a flow chart of a method including (but not limited to) one step of the method of Figure 8.
[0015] Figure 10 is a flow chart of a method including (but not limited to) different steps of the method of Figure 8.

[0016] The present disclosure may be understood by reference to the following detailed description taken in conjunction with the drawings described below, and like reference numerals are used in the various drawings to refer to like components. It is noted that for purposes of clarity of illustration, certain elements in the drawings may not be drawn to scale. While a dash followed by a number may be used to refer to specific instances of an item (e.g., heaters 220-1, 220-2), numbers without parentheses refer to any such item (e.g., Heaters 220). In cases where multiple instances of an item are shown, only some of the instances may be labeled for clarity of illustration.

[0017] Figure 1 schematically illustrates the main elements of the wafer processing system 100. Although system 100 is shown 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 system (e.g., the systems must be wafer processing systems). There is no need to process semiconductors or semiconductors, nor does it necessarily need to utilize plasmas for processing). 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. Processing system 100 is supported by various utilities, which may include gas(es) 155, external power 170, vacuum 160, and optionally others. For clarity of illustration, internal plumbing and electrical connections within processing system 100 are not shown.

[0018] The processing system 100 generates a plasma at a first location and stores the plasma and/or plasma products (e.g., ions, molecular fragments, energized species, etc.) at a second location where processing occurs. It is shown as a so-called indirect plasma processing system directed to a location. Accordingly, in FIG. 1 , plasma processing unit 130 includes a plasma source 132 that supplies plasma and/or plasma products for a process chamber 134 . The process chamber 134 includes one or more workpiece holders 135 and the wafer interface 115 supports a workpiece 50 (e.g., a semiconductor wafer, but other types) to be held for processing. A workpiece (which may be a workpiece) is placed on the 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(es) 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. . The plasma and/or plasma products travel from the plasma source 132 through the diffuser plate 137 to the process chamber 134 where the workpiece 50 is processed. In addition to or alternatively to plasma from plasma source 132, plasma may also be ignited within process chamber 134 for direct plasma processing of workpiece 50.

[0019] Embodiments herein provide new and useful functionality to wafer processing systems. While feature sizes have decreased significantly over the years, semiconductor wafer sizes have increased, allowing more integrated circuits—the integrated circuits have greater functionality—per processed wafer. Processing smaller features while wafers become larger requires significant improvements in processing uniformity. Typically, because chemical reaction rates are temperature sensitive, temperature control across wafers during processing is usually key to uniform processing.

[0020] Additionally, some types of processing (eg, processing that varies from the center of the wafer to the edge) may have radial effects. Some types of process equipment can control these effects better than others, that is, some achieve high radial process uniformity while others do not. Embodiments herein recognize that not only are radial effects important to control, but it would be advantageous to be able to provide radial processing control that can be tailored to compensate for processing that cannot achieve such control. For example, consider a 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, a compensatory etch step will advantageously provide a higher etch rate at the edge of the wafer than at the center of the wafer, thereby depositing The layer will be etched to complete all parts of the wafer simultaneously. Similarly, if the etching process is known to have center-to-edge variations, the compensation deposition prior to the etching process can be adjusted to provide corresponding variations.

[0021] In many such cases of processing with radial effects, a compensating process can be provided by providing a clear center-to-edge temperature change, which is usually because the temperature substantially affects the reaction rates of the processes. Because.

[0022] Figure 2 is a schematic cross-section illustrating exemplary construction details of the workpiece holder 135 of Figure 1. As shown in Figure 2, the workpiece holder 135 includes a substantially cylindrical puck 200, characterized in that it has a puck radius r1 in a radial direction R from the cylindrical axis Z. do. In use, a workpiece 50 (e.g., a wafer) may be placed on the puck 200 for processing. The bottom surface 204 of the puck 200 is taken to be at the level of the middle bottom surface of the puck 200; That is, the puck 200 is positioned in the direction of axis Z, excluding features such as edge rings or other protrusions 206, or indentations 208, which may form attachment points for other hardware. This is taken to be the plane defining the typical bottom surface height of the puck 200. Similarly, the top surface 202 is taken to be a planar surface configured to receive the workpiece 50, with grooves that can be formed (see FIG. 4, e.g., as vacuum channels) and /or is independent of other features that hold the workpiece 50. All such projections, indentations, grooves, rings, etc. do not detract from the nature of the puck 200, which is "substantially cylindrical" in the context of this specification. Puck 200 may also be characterized as having a thickness t between bottom surface 204 and top surface 202, as shown. In certain embodiments, the puck radius r1 is at least four times the puck thickness t, although this is not a requirement.

[0023] Puck 200 defines one or more radial thermal breaks 210, as shown. Thermal breaks 210 are radial recesses defined in the puck 200 that intersect with at least one of the top surface 202 or the bottom surface 204 of the puck 200. The thermal breaks 210 act as the term implies, that is, they provide thermal resistance between the radially outer portion 214 and the radially inner portion 212 of the puck 200. to provide. This facilitates explicit radial (e.g., center-to-edge) thermal control of the radially inner and outer portions of the puck 200, which provides precise thermal matching of the inner and outer portions, or It is advantageous in terms of providing intentional temperature changes across parts. The thermal blocking portions 210 may be characterized as having a thermal blocking depth and a thermal blocking radius. Although the depth of thermal breaks 210 may vary between embodiments, the thermal break depth generally exceeds one-half the thickness t. Although the radial positioning of the thermal breaks 210 may also vary between embodiments, the thermal break radius r2 is generally at least half the puck radius r1, and in other embodiments, r2 may be 3/4, 4/5, 5/6, or more of the puck radius r1. Certain embodiments may use a single thermal break 210, while other embodiments may use two thermal breaks 210 or more (as shown in FIG. 2). The boundary point between the radially inner portion 212 and the radially outer portion 214 is illustrated as the radially average position between the two thermal breaks 210, but in embodiments with a single thermal break 210, such The boundary point may be considered to be the radial midpoint of a single thermal break 210.

[0024] One way in which thermal shields as illustrated in FIG. 2 may be advantageously used is to provide radially applied heating and/or cooling to the inner portion 212 and outer portion 214 of the puck 200. It is provided. 3 is a schematic cross-sectional view illustrating the application of heat sinks and heaters to the inner and outer portions of puck 200. For clarity of illustration, some mechanical details of puck 200 are not shown in FIG. 3 . 3 illustrates a central channel 201 defined by an optional heat sink 230 and puck 200. The central channel 201 is described with respect to FIG. 4 . The inner heaters 220-1 and outer heaters 220-2 are disposed against the puck 200 and are in thermal communication with the puck 200. Although it may be advantageous for heaters 220 to be spread out over a large portion of lower surface 204, in embodiments the distribution of heaters 220 across surface 204 may vary. The heat provided by heaters 220 will substantially control the temperatures of the inner portion 212 and outer portion 214 of the puck 200; Thermal shields 210 assist in thermally isolating parts 212 and 214 from each other to improve the precision of thermal control. Heaters 220 are typically resistive heaters, but other types of heaters (eg, utilizing forced gas or liquid) may be implemented.

[0025] An optional heat sink 230 may also be provided. Heat sink 230 may be controlled to provide a temperature lower than typical operating temperatures, for example, by flowing a heat exchange fluid through the heat sink, or by using a cooling device such as a Peltier cooler. When present, heat sink 230 provides several advantages. One such advantage is to provide a baseline temperature that all parts of the puck 200 will have in the absence of heat provided by heaters 220. That is, although heaters 220 may provide heat, such heat will typically propagate in all directions throughout puck 200. Heat sink 230 provides the ability to bring puck 200 to lower temperatures such that when heater 220 is located in a particular portion of puck 200, the heat generated by the heater simply: The tendency of the heat sink 230 to heat portions of the puck 200, rather than spreading in all directions throughout the puck 200, from which heat from the heater 220 removes heat. exceeds locally.

[0026] A related advantage is that when the temperature settings of the heaters 220 (e.g., the current through the resistive wires) are reduced, the heat sink (e.g., the current through the resistive wires) is reduced so that adjacent portions of the puck 200 respond with relatively rapid heat reduction. 230) can provide rapid heat sinking ability. This may include, for example, loading the workpiece 50 onto the puck 200, providing heat through heaters 220, and adjusting the temperature on the workpiece 50 so that processing can begin quickly to maximize system throughput. It provides the advantage of achieving rapid stabilization of Without thermal communication to allow some heat to be dissipated into heat sink 230, the temperatures reached by portions of puck 200 will decrease only as quickly as other heat dissipation paths allow.

[0027] In embodiments, heaters 220 are typically placed in direct thermal communication with puck 200, while heat sink 230 is in indirect thermal communication with puck 200 through heaters 220. communicates thermally with It is advantageous for heat sink 230 not to be in direct thermal communication with puck 200 since such direct thermal communication may lead to thermal anomalies on the surface of puck 200 (e.g., puck 200 ) will have regions where the temperature approaches the temperature of the heat sink 230 rather than being dominated by the extra heat generated by the heaters 220). Additionally, the heaters 220 have sufficient heat generating capacity such that the heat applied by the heaters 220 overwhelms the indirect thermal coupling of the puck 200 and the heat sink 230, thereby: Heaters 220 can increase the temperature of the inner portion 212 and outer portion 214 of the puck 200 even when some of the heat generated by the heaters 220 is dissipated into the heat sink 230. there is. Accordingly, the heat provided by heaters 220 may be dissipated through heat sink 230, but not immediately. In embodiments, the degree of thermal coupling between puck 200, heaters 220, and heat sink 230 depends on temperature uniformity at the center and edge portions, respectively, rapidity of thermal stabilization, and manufacturing complexity. and cost, and overall energy consumption.

[0028] Another advantage of the heat sink 230 is that it confines the heat generated by the heaters 220 to the vicinity of the puck 200. That is, heat sink 230 may provide an upper thermal limit for adjacent system components to protect them from the high temperatures generated by puck 200. This can improve the mechanical stability of the system and/or prevent damage to temperature-sensitive components.

[0029] Heaters 220 and heat sink 230 may be implemented in various ways. In an embodiment, heaters 220 include several layers coupled together as sub-assemblies, which then connect puck 200 and (optionally) heat sink 230 to form a wafer chuck assembly. ) can be further coupled. Embodiments designed, assembled, and operated as disclosed herein allow for explicit temperature control of edge regions relative to central regions of a workpiece (e.g., a wafer), typically not achievable with prior art systems. Facilitates processing with center-to-edge temperature control.

[0030] Figure 4 is a schematic cross-sectional view of a portion of a wafer chuck and illustrates features of puck 200, a resistive heater acting as heater 220-1, and heat sink 230. 4 shows a portion of the wafer chuck, proximate the cylindrical axis Z of the wafer chuck, and is not drawn to scale for illustrative clarity of smaller features. Puck 200 is typically formed of an aluminum alloy, such as the well-known “6061” alloy type. Puck 200 defines surface grooves or channels 205 that connect on the upper surface 202 of puck 200 and connect with a central channel 201 centered about axis Z. It is shown as Atmospheric pressure (or the gas pressure of lower pressure deposition systems, such as about 10-20 Torr, or relatively high pressure plasmas) forces the workpiece 50 (see FIGS. 1 and 2) against the puck 200. A vacuum may be supplied to the central channel 201 to reduce the pressure in the channels 205 to provide good thermal communication between the puck 200 and the workpiece 50.

[0031] Although the inner resistive heater 220-1 is illustrated in FIG. 4, it should be understood that the following description and illustration of the inner resistive heater 220-1 applies equally to the outer resistive heater 220-2. . Resistive heater 220-1 includes heater traces 264 and buffer layer 266. Heater traces 264 are shown as continuous layers in Figure 4, but it is understood that they exist in layers forming a serpentine pattern to distribute heat evenly along their length (i.e., heater traces 264 ) falls along the cross-sectional plane shown in Figure 4, but in other cross-sections, it will appear to intermittently cross the cross-sectional plane - see Figure 5). Heater traces 264 may be formed, for example, of Inconel approximately 0.0005" to 0.005" thick, although layers of approximately 0.0002" to 0.02" are also useful, and other material choices are also useful. Buffer layer 266 is typically a polymer layer about 0.025" to 0.10" thick, although layers about 0.01" to 0.15" are also useful. Buffer layer 266 may be formed of polyimide, but other polymers and other material choices may be useful. Buffer layer 266 is advantageously a thermally stable electrical insulator (to avoid shorting heater traces 264). The buffer layer 266 is also advantageously compressible, such that when coupled with the much thinner heater trace 264, the opposing surface of the buffer layer 266 is approximately planar for mechanical purposes. Additionally, the buffer layer 266 increases the thermal resistance between the heater trace layer 264 and the heat sink 230, such that when the heater trace layer 264 supplies heat, it heats up more than the heat sink 230. 200), more heat is transferred.

[0032] In embodiments, heater trace layer 264 and buffer layer 266 are thin metal elements that help spread heat from heater trace layer 264 evenly across the surfaces of heater 220-1. Coupled within layers 260, 268. A thin electrical insulating layer 262 is included to prevent the metal layer 260 from shorting the heater trace layer 264; Insulating layer 262 or insulating layer 266 may also serve as a substrate for fabrication of heater trace layer 264 (see Figure 5). The insulating layer 262 is advantageously a thermally stable material and may be formed of a ceramic or a polymer such as polyimide and, in embodiments, has a thickness of about 0.001" to 0.040". Metal layers 260, 268 may be, for example, about 0.005" to 0.050" layers of Al 6061. Metal layers 260, 268 also provide adequate protection to layers 262, 264, and 266, thereby preventing heater 220-1 from later integration with puck 200 and heat sink 230. It can be manufactured and transported as a subassembly for For example, layers 260, 262, 264, 266, 268, and 270, molded to desired dimensions, can be aligned in a stack in registration with each other to form heater 220-1 as a subassembly. and can be bonded by compressing and/or heating the stack. Upon reading and understanding the above disclosure, it will be understood that heater subassemblies as disclosed herein will be approximately planar and for wafer chuck applications will be approximately circular, whereas similarly manufactured subassemblies need not be circular and as described herein. It will be clear to those skilled in the art that the circular bottom surfaces of the cylindrical pucks can be manufactured to fit differently shaped surfaces (eg, squares, rectangles, etc.). Similarly, heater traces for cylindrical pucks may be arranged for azimuthal uniformity and uniform heating density, but heater traces within such subassemblies may be arranged to form locally intense and less intense heating patterns. You can.

[0033] As shown, heater 220-1 is coupled with puck 200 through optional layer 250 and with heat sink 230 through additional optional layer 270. Layers 250 and 270 facilitate heat transfer between heater 220-1 and both puck 200 and heat sink 230; Material choices for layers 250 and 270 include thermally stable polymers. In an embodiment, optional layers 250, 270 are formed from a layer of polymer with a bulk thermal conductivity of about 0.22 W/(m-K). Layers 250 and/or 270 may also be bondably coupleable to puck 200 and layer 260 and heat sink 230 and layer 268, respectively, thereby forming puck 200, heat sink ( 230) may be bonded together with the heaters 220-1 and 220-1. To achieve this, puck 200, layer 250, heaters 220-1 and 220-2, layer 270, and heat sink 230 can all be aligned in registration with one another and compressed. and/or may be bonded by heating.

[0034] In embodiments, heat sink 230 provides a baseline temperature to puck 200 while still allowing inner and outer resistive heaters 220-1 and 220-2 to be centered on puck 200. Allows to provide large-edge temperature control. The temperature of the optional heat sink 230 may be actively controlled. For example, Figure 4 shows a heat sink 230 defining fluid channels 280 through which a heat exchange fluid may be forced. Heat sink 230 may also form thermal fins 290 to increase the contact area and thus the heat exchange efficiency of the fluids within channels 280. As used herein, a “heat exchange fluid” does not require that the mixture always cool the heat sink 230; Heat exchange fluids can add or remove heat. The heat exchange fluid may be provided at a controlled temperature. In one embodiment, the heat sink 230 is formed of an aluminum alloy, such as type “6061”, and the heat exchange fluid is a mixture of 50% ethylene glycol and 50% water, but the heat sink 230 and/or heat exchange fluid is a mixture of 50% ethylene glycol and 50% water. Other materials may be used for this purpose. In still other embodiments, optional heat sink 230 may be a passive heat sink, e.g., heat sink 230 may be a passive radiator, thermal fins, etc., to dissipate heat to the surrounding environment. You can have

[0035] Figure 5 schematically illustrates the layout of heater traces 264 on insulating layer 262. The exact layout of heater traces 264 is not critical, but it is desirable for the layout to be compact and azimuthally uniform. As shown, heater trace 264 may terminate with a pair of bonding pads 274 for subsequent connection with wires that carry power. As shown in Figure 5, heater trace 264 need not extend into central region 269 of inner resistive heater 220-1. One reason for this is that the temperature reached in the area surrounding area 269 within puck 200 will quickly spread across the corresponding area of puck 200. Other reasons, such as to provide a vacuum channel 201 (see FIGS. 3 and 4), fluidic connections for heat exchange fluid, electrical contacts for heater trace 264, and/or other features. The point is that it may be desirable to leave area 269 open for uses.

[0036] An additional advantage of providing at least one thermal barrier 210 intersecting the top surface of the puck 200 is that the mechanical features at least partially form a thermal barrier such that the mechanical features do not create thermal anomalies. The point is that it can be placed within. For example, a wafer chuck typically elevates the wafer a small distance from the chuck to facilitate access by wafer handling tools (typically using a paddle or other device inserted between the wafer and the chuck after the wafer is raised). Lift pins that can be used to do this are provided. However, the lift pins typically retract into holes in the chuck, which can affect the wafer temperature locally during processing. When the thermal break intersects the top surface of the puck 200, there is already a location for such a mechanism to be placed without introducing thermal deformation.

[0037] Figure 6 schematically illustrates a portion of a wafer chuck having a lift pin mechanism 300 that controls the lift pins 310, disposed within a thermal shield 210. Portions of heaters 220 and optional heat sink 230 are also shown. The cross-sectional plane illustrated in FIG. 6 passes through the center of mechanism 300 such that the components of mechanism 300 are within the lower portion of one thermal barrier 210 . Inside and outside the plane shown, puck 200, heat shield 210, and heat sink 230 may have profiles such as those shown in FIGS. 3 and 4, thereby allowing mechanism 300 to be positioned. The resulting heat shield 210 will continue through the puck 200 along its arc (see Figure 7). Additionally, the lift pin mechanism 300 is limited to a fairly small azimuthal angle relative to the central axis of the puck 200 (again, see Figure 7). That is, if the cross-sectional plane is taken at a distance in or out of the plane shown in FIG. 6, the bottom surface of the puck 200 will be continuous along the same plane as the bottom surface 204 shown in FIG. 6; Heat sink 230 will be continuous under puck 200. The small size of the lift pin mechanism 300 limits thermal drift of the puck 200 in the area of the lift pin mechanism 300. FIG. 6 shows the lift pin 310 in a retracted position, which does not create thermal anomalies on the surface of the puck 200 .

[0038] Figure 7 schematically illustrates in a top view an arrangement of three lift fins 310 in which the lift fins 310 are disposed within the thermal shield 210. 7 is not drawn to scale and, in particular, the heat shield 210 is exaggerated so that the lift pin mechanisms 300 and lift pins 310 are clearly visible. Because the lift fins 310 retract well below the average surface of the puck 200 and into the heat shield 210, the lift fins 310 do not create spatial thermal anomalies during processing, thereby causing the lift fins 310 to Portions of a workpiece (e.g., specific integrated circuits located at corresponding locations on a semiconductor wafer) that are processed at locations of ) undergo processing consistent with processing anywhere on the workpiece.

[0039] Figure 8 shows a method 400 for processing a wafer or other workpiece (hereinafter simply referred to as a "product wafer", with the understanding that the concepts may apply to workpieces other than wafers). This is a flow chart. 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 results in clear center-to-edge process control. The first step 420 of method 400 processes the product wafer using a first center-to-edge process variation. The second step 440 of 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 is performed on equipment or in a process environment that unintentionally or uncontrollably creates associated center-to-edge process variations (hereinafter, “uncontrolled variations”). This will work, but it is not required. Additionally, typically, the other is performed on equipment as described herein, thereby allowing the center and edge portions of the product wafer to be explicitly controlled to provide corresponding inverse process changes. through which other center-to-edge process changes (hereinafter referred to as “controlled changes”) are introduced. However, uncontrolled and controlled changes can occur in either order. That is, 420 can introduce either uncontrolled or controlled change, and 440 can introduce the other of uncontrolled change and controlled change. 9 and 10 provide additional guidance to those skilled in the art to enable useful implementation of method 400.

[0040] Figure 9 is a flow diagram of method 401, including but not limited to step 420 of method 400. All of 410-418 and 422 shown in FIG. 9 are considered optional, but in embodiments may be useful when implementing method 400 to achieve useful wafer processing results.

[0041] Step 410 sets 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 involve providing equipment parameters, such as heater settings, that will provide a controlled center-to-edge temperature change. Equipment as described herein in FIGS. 2-7 is useful for providing controlled center-to-edge temperature variation. Step 412 measures equipment characteristics associated with the first center-to-edge process change. Process knowledge about which equipment settings or measured equipment characteristics were successful in creating a known center-to-edge process change (or at least providing a stable process change, even if unintended) It can be acquired over time. Given this process knowledge, if the equipment characteristics measured at 412 are likely to be improved, method 401 can optionally return from 412 to 410 to adjust the equipment characteristics. Step 414 processes one or more test wafers that accommodate the first center-to-edge process change. Step 416 measures one or more characteristics of the first center-to-edge process variation on the test wafer(s) processed in step 414. Method 401 may optionally return from 416 to 410 to adjust the equipment characteristics to take 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 later executed at 440). Additionally, 414 can be performed in parallel with 420. That is, when the process equipment is properly configured, test wafers can be processed simultaneously with product wafers (e.g., the first process involves immersing a cassette of wafers in a liquid bath, ampoule, or diffusion furnace). processing a set of wafers together in a furnace or deposition chamber, etc. for so-called “batch” processes).

[0042] Step 420 processes the product wafer using a first center-to-edge process variation. As described further below, step 422 may be used for correlating information related to step 440, for equipment process control purposes, for correlation to yield or performance of a product wafer, and/or To generate data for use, one or more first center-to-edge characteristics on the product wafer are measured.

[0043] Figure 10 is a flow diagram of method 402, including but not limited to step 440 of method 400. All of 430-436 and 442 shown in FIG. 10 are considered optional, but in embodiments may be useful when implementing method 400 to achieve useful wafer processing results.

[0044] Step 430 sets equipment characteristics associated with the second center-to-edge process change to be created in step 440. For example, if 440 is expected to introduce a controlled change, 430 may involve providing equipment parameters, such as heater settings, that will provide a controlled center-to-edge temperature change. Equipment as described herein in FIGS. 2-7 is useful for providing controlled center-to-edge temperature changes. Step 432 measures equipment characteristics associated with the second center-to-edge process variation. Taking process knowledge into account, as discussed above, method 402 may optionally return from 432 to 430 to adjust the equipment characteristics in light of the equipment characteristics measured at 432. Step 434 processes one or more test wafers accommodating the second center-to-edge process change; The test wafer(s) processed at 434 may include one or more test wafers stored in the first process step at 418, described above. Step 436 measures one or more characteristics of the second center-to-edge process variation on the test wafer(s) processed at 434. Considering previously acquired process knowledge, method 402 may optionally return from 436 to 430 to adjust the equipment characteristics to take into account the center-to-edge process characteristics measured at 436.

[0045] Step 440 processes the product wafer using a second center-to-edge process variation. Additionally, although not shown in method 402, additional test wafers could certainly be processed in parallel with the product wafer. As described above, step 442 may be used for equipment process control purposes, for correlation to the yield or performance of a product wafer, and/or for use in correlating information related to step 420. To generate 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 change any conditions present on the product wafer. That is, the results of 420 and 440 will be locked into the product wafer at the conclusion of 440 regardless of any additional testing performed.

[0046] Although several embodiments have been described, those skilled in the art will understand that various changes, alternative configurations, and equivalents may be used without departing from the spirit of the invention. Additionally, in order to avoid unnecessarily obscuring the present invention, many well-known processes and elements have not been described. Accordingly, the above description should not be taken as limiting the scope of the present invention.

[0047] Processing of workpieces other than wafers may also benefit from improved processing uniformity and is contemplated within the scope of this disclosure. Accordingly, the characterization of chucks herein as “wafer chucks” for holding “wafers” should be understood as equivalent to chucks for holding workpieces of any kind, and similarly “wafer processing systems”. It should be understood as equivalent to processing systems.

[0048] When a range of values is given, each intervening value between the upper and lower limits of such range is added to the decimal point of the lower limit, unless the context clearly indicates otherwise. Up to the tenth is also interpreted as being specifically stated. Each smaller range 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 within the range, and each of the two limits may be included in the smaller ranges, either, neither, or both. Ranges are also encompassed by the invention, subject to any specifically excluded limitations within the stated range. Where a stated range includes one or both of the limits, ranges that exclude either or both of those included limits are also included.

[0049] As used in this specification and the appended claims, the singular forms include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a process” includes a plurality of such processes, reference to “electrode” includes reference to one or more electrodes and equivalents known to those skilled in the art, and so forth. am. Additionally, the words "comprise", "comprising", "include", "including", and "includes", when used in this specification and the claims below, refer to the features referred to, While intended to specify the presence of integers, components, or steps, they do not exclude the presence or addition of one or more other features, integers, components, steps, operations, or groups.

Claims (14)

A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising:
comprising a substantially cylindrical puck characterized by a cylindrical axis, a puck radius about the cylindrical axis, and a puck thickness;
the puck radius is at least four times the puck thickness,
At least a top surface of the cylindrical puck is substantially planar,
The cylindrical puck defines one or more radial thermal breaks,
Each thermal break is characterized by a radial recess that intersects at least one of the top and bottom surfaces of the cylindrical puck,
The radial recess is disposed symmetrically about the cylindrical axis, with a thermal break depth extending from the top or bottom surface of the puck through at least half of the puck thickness, and at least 1/3 of the radius of the puck. Characterized by the thermal break radius, which is 2,
The work holder is,
A first heating device disposed adjacent the bottom surface of the puck and radially inward from the one or more radial thermal breaks with respect to the cylindrical axis, wherein the first heating device is disposed within a radius of the thermal break. In thermal contact with the bottom surface of the puck -,
a second heating device disposed adjacent the bottom surface of the puck and radially outward from the one or more radial thermal breaks with respect to the cylindrical axis, the second heating device being configured to heat the puck outside the radius of the thermal break in thermal contact with the bottom surface of —, and
further comprising a thermal sink extending substantially across a bottom surface of the cylindrical puck;
wherein the first and second heating devices are disposed between the bottom surface of the cylindrical puck and the heat sink.
Workpiece holder for positioning the workpiece for processing. According to claim 1,
The radial recess intersects the top surface, the workpiece holder further comprising at least three lifting elements, the at least three lifting elements configured to lift the workpiece from the top surface, extending over the top surface in the extended state and retracting into the radial recesses in the retracted state for lowering the workpiece onto the top surface.
Workpiece holder for positioning the workpiece for processing. According to claim 1,
At least one of the first and second heating devices includes a heater element trace disposed within a plurality of electrically insulating layers;
the heater element trace comprises a resistive material; and
At least one of the electrically insulating layers comprises polyimide,
Workpiece holder for positioning the workpiece for processing. According to claim 3,
wherein the heater element trace and the electrical insulating layers are disposed within a plurality of metal layers.
Workpiece holder for positioning the workpiece for processing. According to claim 1,
wherein the heat sink includes a metal plate defining one or more fluid channels,
Workpiece holder for positioning the workpiece for processing. According to claim 1,
The first and second heating devices include first and second heater element traces, respectively, disposed between first and second electrical insulating layers;
the first electrical insulating layer is disposed between the first and second heater element traces and the heat sink;
the second electrically insulating layer is disposed between the first and second heater element traces and the bottom surface of the cylindrical puck; and
The first electrically insulating layer is thicker than the second electrically insulating layer, such that the first electrically insulating layer increases the thermal resistance between the heater element traces and the heat sink, causing more heat to be applied when the heater element trace supplies heat. causing more heat to be transferred to the puck than to the heat sink,
Workpiece holder for positioning the workpiece for processing. According to claim 6,
wherein the first electrically insulating layer comprises ceramic,
Workpiece holder for positioning the workpiece for processing. According to claim 1,
first and second heater element traces;
first and second electrically insulating layers;
first and second metal layers; and
further comprising first and second thermally stable polymer layers,
The work holder is from the bottom to the top,
the heat sink;
the first thermally stable polymer layer;
the first metal layer;
the first electrically insulating layer;
the first and second heater element traces at the same level, the second heater element trace being radially outward from the first heater element trace;
the second electrically insulating layer;
the second metal layer;
the second thermally stable polymer layer; and
the puck
bonded with the elements and layers arranged in the physical order of
Workpiece holder for positioning the workpiece for processing. A workpiece holder for positioning a workpiece for processing, the workpiece holder comprising:
a substantially cylindrical puck characterized by a cylindrical axis and a substantially planar top surface, the cylindrical puck defining two radial thermal breaks,
A first one of the radial thermal breaks comprises a radial recess that intersects the bottom surface of the cylindrical puck at a first radius and extends from the bottom surface through at least half the thickness of the puck, characterized;
A second one of the radial thermal breaks includes a radial recess that intersects the top surface at a second radius greater than the first radius and extends from the top surface through at least half the thickness of the puck. Characterized as -;
a heat sink extending substantially below the bottom surface of the puck, the heat sink comprising a metal plate that flows heat exchange fluid through channels to maintain a reference temperature for the puck, the channels comprising: Defined within a metal plate -;
a first heating device disposed between the heat sink and the puck, the first heating device in thermal communication with the bottom surface of the puck and with the heat sink, within the first radius; and
a second heating device disposed between the heat sink and the puck, the second heating device in thermal communication with the bottom surface of the puck, outside the second radius, and with the heat sink;
The first and second heating devices each include first and second heater element traces disposed between first and second electrical insulating layers.
Workpiece holder for positioning the workpiece for processing. According to clause 9,
the first electrical insulating layer is disposed between the first and second heater element traces and the heat sink;
the second electrically insulating layer is disposed between the first and second heater element traces and the bottom surface of the cylindrical puck; and
The first electrically insulating layer is thicker than the second electrically insulating layer, such that the first electrically insulating layer increases the thermal resistance between the heater element traces and the heat sink, causing more heat to be applied when the heater element trace supplies heat. causing more heat to be transferred to the puck than to the heat sink,
Workpiece holder for positioning the workpiece for processing. According to clause 9,
A first electrically insulating layer of the electrically insulating layers includes ceramic,
Workpiece holder for positioning the workpiece for processing. According to clause 9,
first and second metal layers; and
further comprising first and second thermally stable polymer layers,
The work holder is from the bottom to the top,
the heat sink;
the first thermally stable polymer layer;
the first metal layer;
the first electrically insulating layer;
the first and second heater element traces at the same level, the second heater element trace being radially outward from the first heater element trace;
the second electrically insulating layer;
the second metal layer;
the second thermally stable polymer layer; and
the puck
bonded with the elements and layers arranged in the physical order of
Workpiece holder for positioning the workpiece for processing. delete delete

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