JP2018525808A - Thermal management system and method for wafer processing systems - Google Patents

Abstract

The workpiece holder includes a pack having a cylindrical axis, a radius around the cylindrical axis, and a thickness. At least the top surface of the pack is substantially flat and the pack defines one or more heat shields. Each heat shield is a radial recess that intersects at least one of the top and bottom surfaces of the cylindrical pack. The radial recess has a heat shield depth that extends to at least half of the pack thickness and a heat shield radius that is at least one-half of the pack radius. A method of processing a wafer includes processing a wafer using a first process that results in a first center-to-edge process variation, followed by a second center that substantially compensates for the first center-to-edge process. Processing the wafer using a second process that results in two-edge process variation.
[Selection] Figure 4

Description

  The present disclosure is widely applied in the field of processing equipment. More specifically, systems and methods are disclosed for providing spatially optimized processing for workpieces.

  Integrated circuits and other semiconductor products are often manufactured on the surface of a substrate called a “wafer”. While processing may be performed on a group of wafers held on a carrier, processing and testing may be performed on one wafer at a time. If single wafer processing or testing is performed, the wafer may be positioned on the wafer chuck. Other workpieces can be processed on similar chucks. In order to control the temperature of the workpiece for processing, the chuck can be temperature controlled.

  In one embodiment, a workpiece holder positions the workpiece for processing. The workpiece holder includes a substantially cylindrical puck characterized by a cylindrical axis, a pack radius around the cylindrical axis, and a pack thickness. The pack radius is at least four times the pack thickness, at least the top surface of the cylindrical pack is substantially flat, and the cylindrical pack defines one or more radial heat shields. Each heat shield is characterized as a radial recess that intersects at least one of the top and bottom surfaces of the cylindrical pack. The radial recess is a heat shield depth extending from the top or bottom surface of the pack to at least half of the pack thickness, and a heat shield located symmetrically about the cylinder axis and at least one-half of the pack radius. Characterized by part radius.

  In one embodiment, a method for processing a wafer includes processing a wafer using a first process that results in a first center-to-edge process variation followed by a second center-to-edge process. Processing the wafer using a second process that results in edge process variation. The second center-to-edge process variation substantially compensates for the first center-to-edge process variation.

  In one embodiment, a workpiece holder positions the workpiece for processing. The workpiece holder includes a substantially cylindrical pack characterized by a cylindrical axis and a substantially flat top surface. This cylindrical pack defines two radial heat shields. The first of the heat shields is characterized as a radial recess that intersects the bottom surface of the cylindrical pack at a first radius and extends from the bottom surface to at least one-half of the thickness of the pack. It is done. The second of the heat shields is characterized as a radial recess that intersects the upper surface at a second radius greater than the first radius and extends from the upper surface to at least one-half of the pack thickness. Attached. The heat sink extends substantially below the bottom surface of the pack and includes a metal plate that heats through channels defined in the metal plate to maintain a reference temperature of the pack. Flow replacement fluid. A first heating device is disposed between the heat sink and the pack. The first heating device is in thermal communication with the bottom surface of the pack and the heat sink inside the first radius. A second heating device is disposed between the heat sink and the pack. The second heating device is in thermal communication with the bottom surface of the pack and the heat sink outside the second radius.

1 schematically illustrates the main elements of a processing system having a workpiece holder, according to one embodiment. FIG. 2 is a schematic cross-sectional view illustrating exemplary structural details of the workpiece holder of FIG. 1. FIG. 2 is a schematic cross-sectional view illustrating the application of a heater and heat sink to the inner and outer portions of the pack forming part of the workpiece holder of FIG. 1, consistent with one embodiment. FIG. 3 is a schematic cross-sectional view illustrating features of a pack, a resistance heater, and a heat sink consistent with one embodiment. FIG. 5 schematically illustrates a heater trace layout in the inner resistance heater of FIG. 4 consistent with one embodiment. FIG. 6 schematically illustrates a lift pin mechanism disposed in a heat shield, consistent with one embodiment. FIG. FIG. 6 schematically shows a plan view of a three lift pin configuration in which lift pins are disposed in a heat shield, consistent with one embodiment. FIG. 3 is a flow diagram of a method for processing a wafer or other workpiece, consistent with one embodiment. FIG. 9 is a flow diagram of a method that includes (but is not limited to) one step of the method of FIG. FIG. 9 is a flow diagram of a method that includes (but is not limited to) other steps of the method of FIG.

  The present disclosure may be understood by reference to the following detailed description in conjunction with the drawings described below. Like reference numbers are used throughout the several views to represent like components. It should be noted that certain elements in the figures may not be drawn to scale for clarity of the figures. An example of an item can be represented by using a number after the dash (eg, heaters 220-1, 220-2), while a number without parentheses represents any such item (eg, heater 220). When a plurality of examples of items are illustrated, only a part of the examples may be displayed for easy understanding of the figure.

  FIG. 1 schematically shows the main elements of a wafer processing system 100. Although the system 100 is depicted as a single wafer, semiconductor wafer plasma processing system, the techniques and principles herein are not limited to any type of wafer processing system (e.g., not necessarily processing a wafer or semiconductor; It will be apparent to those skilled in the art that the present invention is applicable to systems that do not utilize plasma. 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. The processing system 100 is supported by various utilities, which may include gas (s) 155, external power 170, vacuum 160, and more optionally. For ease of illustration, internal piping and electrical connections within the processing system 100 are not shown.

  The processing system 100 generates a plasma at a first location and directs the plasma and / or plasma product (eg, ions, molecular fragments, excited species, etc.) to a second location where processing is performed. It is shown as a so-called indirect plasma processing system. Thus, in FIG. 1, the plasma processing unit 130 includes a plasma source 132 that supplies plasma and / or plasma products to the processing chamber 134. The processing chamber 134 includes one or more workpiece holders 135 on which a wafer interface 115 is held for processing (e.g., a semiconductor wafer, but another Can be a kind of work piece). When the workpiece 50 is a semiconductor wafer, the workpiece holder 135 is often referred to as a wafer chuck. During operation, gas (s) 155 is introduced into plasma source 132 and radio frequency generator (RF Gen) 165 supplies power to ignite the plasma within plasma source 132. Plasma and / or plasma products travel from the plasma source 132 through the diffuser plate 137 to the processing chamber 134 where the workpiece 50 is processed. A plasma may be ignited in the processing chamber 134 for direct current plasma processing of the workpiece 50 instead of or in addition to the plasma from the plasma source 132.

  The embodiments herein provide new and useful features for wafer processing systems. While the size of semiconductor wafers has increased significantly over the past few years, the feature size has significantly decreased, allowing more integrated circuits with higher order functionality to be obtained for each wafer processed. It has become. Processing smaller features as the wafer grows in size requires a significant improvement in processing uniformity. Since chemical reaction rates are often temperature sensitive, temperature control across the wafer being processed is often important for uniform processing.

  Also, certain types of processing can have radial effects (eg, processing that varies from the center of the wafer to the edge). Some treatment facilities control the above actions better than others. That is, some equipment achieves high radial processing uniformity while other equipment does not. Embodiments of this document will be more advantageous if they allow for the provision of radial process control that can be adapted to compensate not only for radial effects that are important to control, but also for processes that cannot achieve such control. I admit that For example, consider the case where a layer is deposited on a wafer and then selectively etched away, as is common in semiconductor processing. If the deposition step is known to deposit a layer thicker than the wafer center at the wafer edge, compensating the etch step advantageously provides a faster etch rate at the wafer edge than the wafer center. Thereby, the etching of the deposited layer is completed simultaneously in all parts of the wafer. Similarly, if it is known that the etching process has center-to-edge variations, the deposition compensation preceding the etching process can be adjusted to provide the corresponding variations.

  Processing with such radial effects can often provide a compensation process by providing an explicit center-to-edge temperature variation. This is because temperature often has a substantial effect on the reaction rate of the process.

  FIG. 2 is a schematic cross-sectional view illustrating exemplary structural details of the workpiece holder 135 of FIG. As shown in FIG. 2, the work piece holder 135 is substantially cylindrical and is characterized in that it has a pack radius r1 in the radial direction R from the cylindrical axis Z. including. In use, a workpiece 50 (eg, a wafer) can be placed on the pack 200 for processing. The bottom surface 204 of the pack 200 is a median bottom surface height of the pack 200, that is, features such as edge rings or other protrusions 206, or indentations 208 that can be formed in the pack 200 as attachment points for other hardware. Is a plane that defines a typical bottom height of the pack 200 in the direction of the Z-axis, excluding. Similarly, the top surface 202 accommodates the workpiece 50 regardless of the grooves that may be formed therein (eg, as a vacuum channel as seen in FIG. 4) and / or other features that hold the workpiece 50. It is interpreted as a flat surface configured to do. All such protrusions, indentations, grooves, rings, etc. do not detract from the “substantially cylindrical” characterization of the pack 200 in the context of this specification. The pack 200 may also be characterized in that it has a thickness t between the bottom surface 204 and the top surface 202 as shown. In certain embodiments, the pack radius r1 is at least four times the pack thickness t, but this is not a requirement.

  The pack 200 defines one or more radial heat shields 210 as shown. The heat shield 210 is a radial recess defined in the pack 200 that intersects at least one of the top surface 202 and the bottom surface 204 of the pack 200. The heat blocking part 210 acts literally. That is, they provide thermal resistance between the radially inner portion 212 and the radially outer portion 214 of the pack 200. This facilitates systematic radial (eg, center-to-edge) thermal control of the radially inner and radially outer portions of pack 200 and provides precise thermal matching between the inner and outer portions. This is advantageous in that it provides a deliberate temperature variation throughout the inner and outer portions. The heat shield 210 may be characterized in that it has a heat shield depth and a heat shield radius. The depth of the heat shield 210 may vary between embodiments, but typically exceeds one-half of the thickness t. The radial positioning of the heat shield 210 may also vary between embodiments, but the heat shield radius r2 is typically at least one-half of the pack radius r1, and in other embodiments r2 is the pack radius. It can be three quarters, four fifths, five sixths or even larger of r1. Some embodiments may use a single heat shield 210, while other embodiments use two heat shields 210 (see FIG. 2), or more than two heat shields 210. sell. Although the boundary point between the radially inner portion 212 and the radially outer portion 214 is illustrated as the radial average position between the two heat shields 210, an implementation with a single heat shield 210 is shown. In form, such a boundary point can be considered as the radial midpoint of this single heat shield 210.

  One way in which a heat shield such as that shown in FIG. 2 may be advantageously used is to provide heating and / or cooling applied radially to the inner portion 212 and outer portion 214 of the pack 200. It is. FIG. 3 is a schematic cross-sectional view showing the application of the heater and heat sink to the inner and outer portions of the pack 200. Some mechanical details of the pack 200 are not shown in FIG. 3 for clarity of illustration. FIG. 3 shows a central channel 201 defined by the pack 200 and an optional heat sink 230. The central channel 201 is described in connection with FIG. Inner heater 220-1 and outer heater 220-2 are disposed in contact with pack 200 and are in thermal communication with pack 200. While it may be advantageous for the heater 220 to generally extend over most of the lower surface 204, the distribution of the heater 220 across the surface 204 may vary in embodiments. The heat provided by the heater 220 will substantially control the temperature of the inner portion 212 and the outer portion 214 of the pack 200. The heat shield 210 assists in the thermal separation of the portions 212 and 214 from each other to improve the accuracy of thermal control. The heater 220 is typically a resistance heater, but other types of heaters (eg, those using forced gas or forced liquid) may be implemented.

  An optional heat sink 230 may also be provided. The heat sink 230 is controlled to generate a temperature lower than the typical operating temperature, for example, by flowing a heat exchange fluid therethrough or by using a cooling device such as a Peltier cooler. sell. The heat sink 230 provides several advantages when present. One such advantage is to provide a reference temperature that all parts of the pack 200 will have in situations where the heater 220 does not provide heat. That is, the heater 220 can provide heat, but such heat typically propagates in all directions throughout the pack 200. When the heater 220 is located on a particular portion of the pack 200, the heat generated by the heater does not simply spread throughout the pack 200 in any direction, but the heat from the heater 220 of the pack 200 is this heat. The heat sink 230 provides the ability to bring the pack 200 to a lower temperature so as to heat the part that locally exceeds the nature of the heat sink 230 that removes the heat.

  One related advantage is that the heat sink 230 reacts to a relatively rapid temperature drop in adjacent portions of the pack 200 when the temperature setting of the heater 220 (eg, current through the resistance wire) is reduced. It can provide rapid heat sink performance. In this way, for example, it is possible to place the workpiece 50 on the pack 200, to provide heat through the heater 220, and to achieve rapid stabilization of the temperature at the workpiece 50. The benefit is that can be started quickly to maximize system throughput. Without heat communication that allows some heat to diffuse to the heat sink 230, the temperature reached in each part of the pack 200 will only drop as fast as other heat diffusion paths allow.

  In an embodiment, the heater 220 is typically placed in direct thermal communication with the pack 200, while the heat sink 230 is in indirect thermal communication with the pack 200 through the heater 220. Advantageously, the heat sink 230 is not in direct thermal communication with the pack 200. This is because such direct heat communication can lead to thermal anomalies on the surface of the pack 200 (for example, the pack 200 is not strongly affected by the extra heat generated by the heater 220, but the temperature is set to the temperature of the heat sink 230). Can have a region that is close.) In addition, since the heater 220 has sufficient heat generation performance so that the heat applied by the heater 220 can surpass the indirect heat connection between the pack 200 and the heat sink 230, a part of the heat generated by the heater 200 is obtained. While diffusing into the heat sink 230, the temperature of the inner portion 212 and the outer portion 214 of the pack 200 can be increased. Thus, the heat provided by the heater 220 can diffuse through the heat sink 230, but not immediately. In an embodiment, in order to balance considerations such as temperature uniformity in each of the center and edge portions, rapid temperature stabilization, manufacturing complexity and cost, and overall energy consumption, The degree of thermal coupling between the heater 220 and the heat sink 230 can be adjusted according to the principles of this document.

  Yet another advantage of the heat sink 230 is that the heat generated by the heater 220 is limited to the vicinity of the pack 200. That is, the heat sink 230 can provide a thermal limit for such components to protect neighboring system components from the high temperatures generated by the pack 200. This can improve the mechanical stability of the system and / or prevent damage to temperature sensitive components.

  The heater 220 and the heat sink 230 can be implemented in various ways. In one embodiment, the heater 220 includes several layers connected together as subassemblies, which are then further connected to the pack 200 and (optionally) the heat sink 230 to provide a wafer chuck. An assembly can be formed. Embodiments designed, assembled and operated as disclosed herein allow for systematic temperature control of the edge region relative to the central region of the workpiece (eg, wafer), typically of the prior art. Facilitates processing using systematic center-to-edge temperature control that is not possible with the system.

  FIG. 4 is a schematic cross-sectional view of a portion of the wafer chuck, showing the features of the pack 200, the resistance heater acting as the heater 220-1, and the heat sink 230. FIG. FIG. 4 represents a portion of the wafer chuck near the cylindrical axis Z, but is not drawn to scale for the sake of clarity. The pack 200 is typically formed of an aluminum alloy (eg, the well known “6061” alloy type). The pack 200 is shown to define a surface groove or channel 205 on the upper surface 202 of the pack 200 that connects with a central channel 201 centered about the Z axis. Atmospheric pressure (or a relatively high pressure plasma or gas pressure in a low pressure deposition system, eg, about 10-20 Torr) urges the workpiece 50 (see FIGS. 1 and 2) to abut the pack 200. A vacuum can be supplied to the central channel 201 to reduce the pressure in the channel 205 to provide good thermal communication between the pack 200 and the workpiece 50.

  Although the inner resistance heater 220-1 is shown in FIG. 4, it should be understood that the illustration of the inner resistance heater 220-1 and the following description apply equally to the outer resistance heater 220-2. Resistive heater 220-1 includes a heater trace 264 and a buffer layer 266. Although heater trace 264 is illustrated as a continuous layer in FIG. 4, it should be understood that it exists as a layer that forms a serpentine pattern to distribute heat evenly along its entire length (ie, heater trace 264 is 4 is present along the cross-sectional plane shown in FIG. 4, but in other cross-sectional views, it may appear intermittently intersecting this cross-sectional plane (see FIG. 5). The heater trace 264 can be formed of, for example, Inconel with a thickness of about 0.0005 "to 0.005", but a layer of about 0.0002 "to 0.02" is also useful if other materials are selected. It is. The buffer layer 266 is typically a polymer layer having a thickness of about 0.025 "to 0.10", although a layer of about 0.01 "to 0.15" is also useful. The buffer layer 266 may be formed of polyimide, but it may be useful to select other polymers and other materials. The buffer layer 266 is advantageously a thermally stable electrical insulator (to avoid a short circuit of the heater trace 264). The buffer layer 266 is also advantageously compressible such that when coupled with a much thinner heater trace 264, the opposing surface of the buffer layer 266 is approximately flat for mechanical purposes. . The buffer layer 266 also increases the thermal resistance between the heater trace layer 264 and the heat sink 230 so that when the heater trace layer 264 supplies heat, more heat than the heat transmitted to the heat sink 230 is packed. 200.

  In an embodiment, the heater trace layer 264 and the buffer layer 266 are coupled between thin metal layers 260, 268 that assist in the uniform diffusion of heat from the heater trace layer 264 across the entire surface of the heater 220-1. The A thin electrical insulation layer 262 is included to prevent the metal layer 260 from shorting with the heater trace layer 264. The insulating layer 262 or the insulating layer 266 can also act as a substrate for manufacturing the heater trace layer 264 (see FIG. 5). 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 ″. Have. The metal layers 260, 268 may be, for example, a layer of Al 6061 from about 0.005 "to 0.050". Metal layers 260, 268 also provide moderate protection to layers 262, 264, and 266 so that heater 220-1 is manufactured and shipped as a subassembly that is later integrated with pack 200 and heat sink 230. Can be done. For example, to form heater 220-1 as a subassembly, layers 260, 262, 264, 266, 268, and 270 that are shaped to the desired dimensions are aligned in the stack so that they are aligned with each other. It can be bonded by compression and / or heating. Upon reading and understanding the above disclosure, the heater subassembly disclosed herein is generally planar and generally circular for wafer chuck applications, but similarly fabricated subassemblies are circular. Those skilled in the art will appreciate that it may not be necessary and may be manufactured to conform to a surface (eg, square, rectangular, etc.) shaped differently from the circular bottom of the cylindrical pack described herein. Would. Similarly, heater traces for cylindrical packs can be arranged to be uniform in the azimuthal direction and to have uniform heat density, but the heater traces in such subassemblies are not locally strong. May be arranged to form a locally high and locally low heating pattern.

  The heater 220-1 is connected to the pack 200 via the option layer 250 and to the heat sink 230 via a further option layer 270 as shown. Layers 250 and 270 facilitate heat transfer between heater 220-1 and both pack 200 and heat sink 230. The material choices for layers 250 and 270 include thermally stable polymers. In one embodiment, optional layers 250, 270 are formed of a layer of polymer having a bulk thermal conductivity of about 0.22 W / (mK). Layers 250 and / or 270 may further be applied to pack 200 and layer 260 and heat sink 230 and layer 268 such that pack 200 and heat sink 230 can be bonded together with heaters 220-1 and 220-1. Each can be glueable. To accomplish this, pack 200, layer 250, heaters 220-1 and 220-2, layer 270, and heat sink 230 are all aligned to each other and can be bonded by compression and / or heating. .

  In an embodiment, the heat sink 230 allows the inner and outer resistance heaters 220-1 and 220-2 to provide center-to-edge temperature control to the pack 200 while providing a reference temperature for the pack 200. . The temperature of the optional heat sink 230 can be actively controlled. For example, FIG. 4 shows a heat sink 230 that defines a fluid channel 280 through which heat exchange fluid may flow. The heat sink 230 can also be formed with heat fins 290 to increase the contact area of the fluid in the channel 280 and thus the heat exchange efficiency. In this document, the “heat exchange fluid” does not require that the heat sink 230 be constantly cooled. The heat exchange fluid can either add or remove heat. The heat exchange fluid can be provided at a controlled temperature. In one embodiment, the heat sink 230 is formed of an aluminum alloy such as “6061” species 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. Other materials may be used. In yet another embodiment, the optional heat sink 230 may be a passive heat sink (eg, the heat sink 230 may be a passive radiator), with heat fins or the like to spread the heat to the surrounding environment. Can have.

  FIG. 5 schematically shows the layout of the heater trace 264 on the insulating layer 262. This layout of the heater trace 264 is not critical, but it is desirable that the layout be dense and uniform in the azimuthal direction. The heater trace 264 may terminate at a pair of adhesive pads 274 that are later connected to a power supplying wire, as shown. As shown in FIG. 5, the heater trace 264 need not extend into the central region 269 of the inner resistance heater 220-1. One reason for this is that the temperature reached in the area around the region 269 in the pack 200 diffuses rapidly throughout the corresponding area of the pack 200. Another reason is for other uses, such as providing vacuum channel 201 (see FIGS. 3 and 4), fluid communication of heat exchange fluid, electrical contact of heater traces 264, and / or other features, etc. This means that it is desirable to leave the area 269 free.

  A further advantage of providing at least one heat shield 210 that intersects the top surface of the pack 200 is that these mechanical features are at least partially within the heat shield so that the mechanical features do not cause thermal anomalies. It can be arranged in. For example, a wafer chuck typically raises the wafer to a distance from the chuck and is accessed by a wafer handling tool (typically a paddle that is inserted between the wafer and the chuck after the wafer has been raised. Or use other devices to provide lift pins that can be used to facilitate. However, the lift pins typically retract into the holes in the chuck, and such holes can locally affect the wafer temperature during processing. If the heat shield intersects the top surface of the pack 200, there is already a place where such a mechanism is placed without causing a thermal anomaly.

  FIG. 6 schematically illustrates a portion of the wafer chuck having a lift pin mechanism 300 that controls the lift pins 310 disposed within the heat shield 210. The heater 220 and optional heat sink 230 are also partially shown. The cross-sectional plane shown in FIG. 6 passes through the center of the mechanism 300, so that the components of the mechanism 300 are in the lower part of one heat shield 210. Since the pack 200, the heat blocking part 210, and the heat sink 230 may have shapes similar to those shown in FIGS. 3 and 4 at the back and front of the illustrated plane, the mechanism 300 is disposed inside. The heat shield 210 is continued along its arc through the pack 200 (see FIG. 7). Further, the lift pin mechanism 300 is limited to a fairly narrow azimuth angle with respect to the central axis of the pack 200 (see also FIG. 7). That is, if the cross-sectional plane is cut at a certain distance from the back or front of the plane shown in FIG. 6, the bottom surface of the pack 200 continues along the same plane illustrated as the bottom surface 204 in FIG. The sink 230 should have been continuous under the pack 200. The small size of the lift pin mechanism 300 limits the thermal variation of the pack 200 in the area of the lift pin mechanism 300. FIG. 6 shows the lift pin 310 in a retracted position where the lift pin 310 does not cause a thermal anomaly on the surface of the pack 200.

  FIG. 7 schematically shows a plan view of a three lift pin configuration in which lift pins 310 are disposed within the heat shield 210. FIG. 7 is not to scale. In particular, the heat blocking unit 210 is enlarged to show the lift pin mechanism 300 and the lift pin 310 in an easily understandable manner. The lift pins 310 retreat considerably below the average surface of the pack 200 in the heat shield 210, so that no spatial thermal anomalies occur during processing. Thus, the portion of the workpiece being processed at the location of the lift pins 310 (eg, a specific integrated circuit located at the corresponding location on the semiconductor wafer) is consistent with the processing of the workpiece at other locations. Go through the process.

  FIG. 8 is for processing wafers or other workpieces (hereinafter simply referred to as “product wafers” for the sake of convenience, but this concept may be applied to workpieces other than wafers). FIG. 4 is a flow diagram of a method 400. The method 400 is described in connection with FIGS. 2-8, which can be used to provide systematic center-to-edge thermal control (which in turn enables systematic center-to-edge process control). Thermal management devices can make it possible on their own. The first step 420 of the method 400 processes the product wafer with a first center-to-edge process variation. The second step 440 of the method 400 processes the product wafer with a second center-to-edge process variation that compensates for the first center-to-edge variation. Typically, one or the other of 420 and 440 is implemented in a facility or process environment that generates unrelated or uncontrollable associated center-to-edge process variations (hereinafter “uncontrolled variations”). This is not necessary. In addition, another center-to-edge process variation (hereinafter “control”) is typically achieved through thermal management techniques that allow systematic control of the center and edge portions of the product wafer and provide corresponding inverse process variations. The other step is carried out in an installation as described in this document so that "variation") results. However, non-control variation and control variation can occur in either order. That is, 420 can provide either non-control variation or control variation, and 440 can provide the other of non-control variation or control variation. 9 and 10 provide additional guidance to those skilled in the art to enable useful operation of the method 400.

  FIG. 9 is a flow diagram of a method 401 that includes (but is not limited to) step 420 of the method 400. All of 410-417 and 422 shown in FIG. 9 are considered optional, but in an embodiment, implementation of the method 400 may help achieve useful wafer processing results.

  Step 410 sets equipment characteristics associated with the first center-to-edge process variation occurring at 420. For example, if 420 is expected to result in control variation, 410 may include providing equipment parameters such as heater settings that provide controlled center-to-edge temperature variation. Equipment such as that described in FIGS. 2-7 of this document is useful for providing controlled center-to-edge temperature variations. Step 412 measures equipment characteristics associated with the first center-to-edge process variation. Process knowledge over time as to what equipment settings or measured equipment characteristics will successfully generate known center-to-edge process variations (or provide at least stable process variations, if not intentional) Can be acquired automatically. In view of this process knowledge, the method 401 may optionally return from 412 to 410 to adjust the equipment characteristics if the equipment characteristics measured at 412 are considered to be improved. Step 414 processes one or more test wafers subject to the first center-to-edge process variation. Step 416 measures one or more 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 facility characteristics based on the center-to-edge process characteristics measured at 416. If the test wafer is processed at 414, at 418, testing in a second process (eg, a process performed later at 440) may optionally be omitted. Also, 414 can be implemented in parallel with 420. That is, if the process equipment is properly configured, the test wafer can be processed simultaneously with the product wafer (eg, a so-called “batch” process where the first process immerses the cassette of wafers in a liquid bath). The wafer set is processed at once in one ampoule, diffusion furnace, or deposition chamber).

  Step 420 processes the product wafer with a first center-to-edge process variation. Step 422 measures one or more first center-to-edge characteristics on the product wafer, as described below, for facility process control, for correlation with product wafer yield or performance, and / or Alternatively, data is generated for use in correlation with surrounding information in step 440.

  FIG. 10 is a flow diagram of a method 402 that includes (but is not limited to) step 440 of the method 400. All of 430-436 and 442 shown in FIG. 10 are considered optional, but embodiments may help achieve useful wafer processing results in performing method 400.

  Step 430 sets equipment characteristics associated with the second center-to-edge process variation that occurs in step 440. For example, if 440 is expected to result in control variation, 430 may include providing equipment parameters such as heater settings that provide controlled center-to-edge temperature variation. Equipment such as that described in FIGS. 2-7 of this document is useful for providing controlled center-to-edge temperature variations. Step 432 measures equipment characteristics associated with the second center-to-edge process variation. In view of the process knowledge described above, the method 402 may optionally return from 432 to 430 to adjust the equipment characteristics based on the equipment characteristics measured at 432. Step 434 processes one or more test wafers that are subject to a second center-to-edge process variation. The test wafer (s) processed at 434 may include one or more test wafers that have not undergone the first process step 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. Given the process knowledge already acquired, the method 402 may optionally return from 436 to 430 to adjust the facility characteristics in light of the center-to-edge process characteristics measured at 436.

  Step 440 processes the product wafer with a second center-to-edge process variation. Also, although not shown in method 402, it is certain that additional test wafers can be processed in parallel with the product wafer. Step 442 measures one or more first center-to-edge characteristics on the product wafer, as described above, for facility process control, for correlation with product wafer yield or performance, and / or Alternatively, data is generated for use in correlating with 420 surrounding information. Such measurements can be performed on any test wafers processed in parallel with the product wafer, but in any case, 442 generally does not further alter any conditions present on the product wafer. Absent. That is, regardless of whether further testing is performed, the results of 420 and 440 will be finalized on the product wafer at the end of 440.

  While several embodiments have been described, those skilled in the art will recognize that various modifications, alternative constructions, and equivalents may be used without departing from the essence of the invention. In addition, some 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 invention.

  Processing of workpieces other than wafers can also benefit from improved processing uniformity and is considered to be within the scope of this disclosure. Thus, the chuck characterization in this document as a “wafer chuck” for holding a “wafer” is equivalent to a chuck for holding any type of workpiece, It should be understood that a “wafer processing system” is similarly equivalent to a processing system.

  If a range of values is provided, each intervening value between the upper and lower limits of the range is also explicitly disclosed up to one-tenth of the lower limit unit unless the context clearly indicates otherwise. I want you to understand. Each of the narrower ranges between any specified or intervening value in a specified range and any other specified or intervening value in that specified range is included. The upper and lower limits of these narrower ranges may be individually included or excluded from that range, and if any of the limit values are included in the narrower range, Is not included in the narrower range, or each range where both limit values are included in the narrower range, subject to any limit value explicitly excluded from the specified range. Are included within the scope of the present invention. When the specified range includes one or both of the limit values, a range excluding one or both of the included limit values is also included.

  In this document 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 “a process” includes a plurality of such processes, and a reference to “the electrode” includes one or more electrodes, and those skilled in the art. Including reference to known equivalents, and so on. The terms “comprise / comprising” and “include / inclusion / includes” as used in this specification and the following claims are also defined features, integer values, components, Or is intended to demonstrate the presence of a step, but does not exclude the presence or addition of one or more other features, integer values, components, steps, actions, or groups.

Claims (14)

A workpiece holder for positioning the workpiece for processing,
A substantially cylindrical pack characterized by a cylindrical axis, a pack radius around the cylindrical axis, and a pack thickness;
The pack radius is at least four times the pack thickness;
At least the upper surface of the cylindrical pack is substantially flat;
The cylindrical pack comprises a cylindrical pack defining one or more radial heat shields;
Each heat shield is characterized as a radial recess intersecting at least one of the top and bottom surfaces of the cylindrical pack, the radial recess being
A heat shield depth extending from the top or bottom surface of the pack to at least half of the pack thickness; and
A workpiece holder characterized by a heat shield radius arranged symmetrically about the cylindrical axis and at least one-half of the pack radius.   The radial recess intersects the top surface and extends above the top surface in an extended state to raise the workpiece from the top surface and to lower the workpiece onto the top surface The workpiece holder of claim 1, further comprising at least three lift elements that retract into the radial recess in the retracted state. A first heating device disposed adjacent to the bottom surface of the pack and radially inward from the one or more heat shields with respect to the cylindrical axis, the inner side of the heat shield radius A first heating device in thermal contact with the bottom surface of the pack;
A second heating device disposed adjacent to the bottom surface of the pack and radially outward from the one or more heat shields with respect to the cylindrical axis, the outer side of the heat shield radius The workpiece holder of claim 1, further comprising a second heating device in thermal contact with the bottom surface of the pack. At least one of the first heating device and the second heating device comprises a heater element trace disposed between a plurality of electrically insulating layers;
The heater element trace comprises a resistive material;
4. A workpiece holder according to claim 3, wherein at least one of the electrically insulating layers comprises polyimide.   The workpiece holder according to claim 4, wherein the heater element trace and the electrically insulating layer are disposed between a plurality of metal layers. A heat sink extending substantially over the entire bottom surface of the cylindrical pack;
The first heating device and the second heating device are disposed between the heat sink and the bottom surface of the cylindrical pack;
4. The workpiece holder of claim 3, wherein the heat sink comprises a metal plate that defines one or more fluid channels. A method for processing a wafer, comprising:
Processing the wafer using a first process that results in a first center-to-edge process variation;
Subsequently processing the wafer using a second process that results in a second center-to-edge process variation;
The method of processing a wafer, wherein the second center-to-edge process variation substantially compensates for the first center-to-edge process variation. Processing the wafer using the first process comprises depositing a material layer on the wafer;
The first center-to-edge variation is a thickness variation of the thickness of the material layer;
Processing the wafer using the second process comprises etching the material layer in at least selected areas of the wafer;
The second center-to-edge variation is an etch rate variation such that the material layer can be etched in at least the selected area of the wafer with a substantially constant etch time from the center to the edge of the wafer. 8. A method for processing a wafer as claimed in claim 7.   The method of processing a wafer according to claim 7, wherein processing the wafer using at least one of the first process and the second process includes establishing a center-to-edge temperature variation across the wafer. . Establishing the center-to-edge temperature variation across the wafer;
Placing the wafer in thermal communication with the top surface of the cylindrical pack characterized by the radius of the cylindrical pack and the pack thickness between the top and bottom surfaces of the cylindrical pack; ,
Providing a first heater in thermal communication with the central region of the pack to establish the center-to-edge temperature variation; and
The method of processing a wafer according to claim 9, comprising providing a second heater in thermal communication with an edge region of the pack. Establishing the center-to-edge temperature variation across the wafer may cause the pack to have at least one of the top surface and the bottom surface as a heat shield between the edge region of the pack and the central region of the pack. Providing at least one radial recess that intersects with
The method of processing a wafer according to claim 10, wherein the radial recess is characterized by a heat shield depth extending from the top or bottom surface of the pack to at least half of the pack thickness.   Establishing the center-to-edge temperature variation across the wafer further provides the at least one radial recess at a radius that is at least three quarters of the radius of the cylindrical pack. The method of processing a wafer according to claim 11, comprising: Establishing the center-to-edge temperature variation across the wafer;
Providing a heat sink in thermal communication with the first heater and the second heater;
11. The method of processing a wafer according to claim 10, further comprising flowing a controlled temperature heat exchange liquid through a fluid channel in the heat sink. A workpiece holder for positioning the workpiece for processing,
A substantially cylindrical pack, characterized by a cylindrical axis and a substantially flat top surface, defining two radial heat shields;
A radial direction in which a first one of the heat shields intersects the bottom surface of the cylindrical pack at a first radius and extends from the bottom surface to at least one-half of the thickness of the pack. Characterized as a recess,
A second one of the heat shields intersects the top surface at a second radius greater than the first radius and extends from the top surface to at least one-half of the thickness of the pack. A cylindrical pack, characterized as a radial recess;
A heat sink extending substantially below the bottom surface of the pack, the heat sink comprising a metal plate for flowing a heat exchange fluid through a channel defined therein to maintain a reference temperature of the pack When,
A first heating device disposed between the heat sink and the pack, wherein the first heating device is in thermal communication with the bottom surface of the pack and the heat sink inside the first radius;
A second heating device disposed between the heat sink and the pack, wherein the second heating device is in thermal communication with the bottom surface of the pack and the heat sink outside the second radius. Workpiece holder provided.

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