JP6925977B2 - Thermal management systems and methods for bolted wafer chucks for wafer processing systems - Google Patents

Description

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

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

In one embodiment, the workpiece holder positions the workpiece for processing. The workpiece holder is arranged to communicate heat with the substantially cylindrical pack and the radial inner portion of the pack with the first heating device and the radial outer portion of the pack. Includes a second heating device and a heat sink arranged to communicate heat with the pack. The first and second heating devices can be individually controlled with respect to each other, and the degree of heat communication with the pack is higher than the degree of heat communication between the heat sink and the pack.

In one embodiment, the method of controlling the spatial temperature distribution of the workpiece is substantially cylindrical by flowing a heat exchange fluid at the controlled temperature through a channel in a heat sink that communicates with the pack. By providing a reference temperature for the pack and activating a first heating device arranged to communicate heat with the radial inner portion of the pack, the pack is radially up to a first temperature above the reference temperature. By raising the temperature of the inner part and operating a second heating device arranged to communicate heat with the radial outer part of the pack, the outer part of the pack is radially outer to a second temperature higher than the reference temperature. Includes raising the temperature of the part and placing the workpiece on the pack.

In one embodiment, the workpiece holder that positions the workpiece for processing comprises a substantially cylindrical pack characterized by a cylindrical shaft and a substantially flat top surface. This pack defines two radial heat barriers. The first heat shield is characterized as a radial recess that intersects the bottom of the pack at a first radius and extends from the bottom to at least half the thickness of the pack. The second heat shield is characterized as a radial recess that intersects the top surface of the pack at a second radius greater than the first radius and extends from the top surface to at least half the thickness of the pack. .. The first and second heat shields define a boundary between the radial inner portion of the pack and the radial outer portion of the pack. The pack includes a first heating device embedded within the radial inner portion of the pack and a second heating device embedded within the radial outer portion of the pack. The workpiece holder is a heat sink that extends substantially below the bottom of the pack and includes a metal plate that allows heat exchange fluid to flow through internally defined channels to maintain the pack's reference temperature. , Including heat sink. The thermal sink is mechanically and thermally connected to the pack at the attachment point, where the thermal sink is less than the degree of thermal communication between each of the first and second heating devices and the pack. Provides heat communication between the pack and the pack.

The main elements of the processing system having the workpiece holder according to one embodiment are shown schematically. FIG. 5 is a schematic cross-sectional view showing exemplary structural details of the workpiece holder of FIG. FIG. 5 is a schematic cross-sectional view showing the incorporation of a heater and a heat sink into the inner and outer portions of a pack forming a portion of the workpiece holder of FIG. 1, which conforms to one embodiment. FIG. 6 is a schematic cross-sectional view showing a portion of a wafer chuck that conforms to one embodiment and shows the features of a pack, resistance heater, and heat sink. The underside of a pack in which cable heaters are internally mounted as inner and outer resistance heaters, conforming to one embodiment, is schematically shown. FIG. 3 is a detailed view of a portion of the pack and optional heat sink of FIG. 4 near the fastener. An embodiment of an uncompressed wave washer that conforms to one embodiment is schematically shown. FIG. 6A is a bottom view of the pack and optional heat sink shown in FIG. 6A as viewed from below. A lift pin mechanism arranged in a heat shield, which conforms to one embodiment, is shown schematically. FIG. 5 is a schematic view of a three-lift pin configuration in which the lift pins are arranged in a heat shield, which conforms to one embodiment. FIG. 5 is a flow chart of a method for processing a wafer or other workpiece that conforms to one embodiment. FIG. 5 is a flow chart of a method including, but not limited to, one step of the method of FIG. FIG. 5 is a flow diagram of a method including, but not limited to, another step 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. Similar reference numbers are used throughout some drawings to represent similar components. Note that certain elements in the figure may not be drawn to scale for clarity. Specific examples of items can be represented by using the numbers after the dash (eg heaters 220-1, 220-2), while the unbracketed numbers represent any such item (eg heater 220). If multiple examples of an item are illustrated, only some of the examples may be labeled for clarity.

FIG. 1 schematically shows the main elements of the wafer processing system 100. The system 100 is depicted as a single wafer / semiconductor wafer plasma processing system, but the techniques and principles of this document apply to any type of wafer processing system (eg, not necessarily processing wafers or semiconductors, but necessarily processing). It will be clear to those skilled in the art that it is applicable to systems that do not utilize plasma). The processing system 100 includes a wafer interface 115, a user interface 120, a plasma processing unit 130, a controller 140, and a housing 110 for one or more power supplies 150. The processing system 100 is supported by a variety of utilities, including gas (s) 155, external power 170, vacuum 160, and optionally others. For the sake of clarity, the 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 products (eg ions, molecular fragments, excited species, etc.) to a second location where processing takes place. , So-called indirect plasma processing system. Therefore, 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 the wafer interface 115 is held for processing the workpiece 50 (eg, a semiconductor wafer, but another). It can also be a type of workpiece). When the workpiece 50 is a semiconductor wafer, the workpiece holder 135 is often referred to as a wafer chuck. During operation, the gas (s) 155 are introduced into the plasma source 132 and the radio frequency generator (RF Gen) 165 supplies power to ignite the plasma in the plasma source 132. The plasma and / or plasma product travels from the plasma source 132 through the diffuser plate 137 to the processing chamber 134 in which the workpiece 50 is processed. Instead of or in addition to the plasma from the plasma source 132, the plasma may be ignited in the processing chamber 134 due to the DC plasma processing of the workpiece 50.

The embodiments of this document provide new and useful functions for the plasma processing system. While semiconductor wafers have increased in size over the past few years, feature sizes have also decreased significantly, making it possible to obtain more integrated circuits with higher functionality for each wafer processed. .. Processing smaller features as wafers grow in size requires significant improvements in processing uniformity. Since the chemical reaction rate is often temperature sensitive, temperature control over the entire wafer during processing is often important for uniform processing.

Also, certain treatments may have radial effects (eg, treatments that fluctuate from the center to the edges of the wafer). Some processing facilities control the above effects better than others. That is, some equipment achieves high radial processing uniformity, while others do not. Embodiments of this document are further advantageous if the radial action is controlled advantageously and it is possible to provide a radial process that can be optimized to compensate for the process that cannot achieve such control. Is acknowledged. For example, consider the case where layers are deposited on a wafer and then selectively etched off, which is common in semiconductor processing. If it is known that the deposition step deposits a layer thicker than the center of the wafer on the edge of the wafer, compensating for the etching step advantageously provides a faster etching rate at the edge of the wafer than the center of the wafer. , Thereby etching the deposited layer on all parts of the wafer at the same time. Similarly, if the etching process is known to have center-to-edge variation, the deposition compensation preceding the etching process can be adjusted to provide the corresponding variation.

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

FIG. 2 is a schematic cross-sectional view showing exemplary structural details of the workpiece holder 135 of FIG. As shown in FIG. 2, the workpiece holder 135 is characterized in that it is substantially cylindrical and has a pack radius r1 in the radial direction R from the cylindrical axis Z. including. During use, the workpiece 50 (eg, wafer) may be placed on the pack 200 for processing. The bottom surface 204 of the pack 200 is the median bottom height of the pack 200, that is, features such as edge rings or other protrusions 206, or recesses 208 that can be formed on the pack 200 as mounting points for other hardware. It is interpreted as a plane defining the typical bottom height of the pack 200 in the Z-axis direction, excluding. Similarly, the top surface 202 adapts to the work piece 50 regardless of the grooves that can be formed there (eg, as the vacuum channel seen in FIG. 4) and / or other features that hold the work piece 50. It is interpreted as a flat surface configured to do so. All such protrusions, indentations, grooves, rings, etc. do not impair the characterization of Pack 200 as "substantially cylindrical" in the context of this specification. The pack 200 can also be characterized in that it has a thickness t between the bottom surface 204 and the top surface 202, as shown. In some 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 barriers 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 shield 210 acts literally. That is, they provide thermal resistance between the radial inner portion 212 and the radial outer portion 214 of the pack 200. This facilitates systematic radial (eg, center-to-edge) thermal control of the radial inner and radial outer portions of the pack 200 and provides precise thermal matching between the inner and outer portions. It is advantageous in that it provides intentional temperature fluctuations over the inner and outer portions. The heat breaker 210 can be characterized in that it has a heat breaker depth and a heat breaker radius. The depth of the heat shield 210 can vary from embodiment to embodiment, but usually exceeds one half of the thickness t. The radial position of the heat shield 210 may also vary between embodiments, but the heat shield radius r2 is usually at least half 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 barrier 210, while other embodiments may use two heat shields 210 (see FIG. 2), or more than two heat shields 210. .. The boundary point between the radial inner portion 212 and the radial outer portion 214 is shown as the radial average position between the two thermal barriers 210, but has a single thermal barrier 210. In morphology, such a boundary point can be considered to be the radial midpoint of this single thermal barrier 210.

One method in which a heat shield as shown in FIG. 2 can be advantageously used is to provide heating and / or cooling applied radially to the inner and / outer portions 212 of the pack 200. Is. FIG. 3 is a schematic cross-sectional view showing the incorporation of the heater and heat sink into the inner and outer portions of the pack 200. Some mechanical details of Pack 200 are not shown in FIG. 3 for clarity. FIG. 3 shows a central channel 201 defined by the pack 200 and an optional thermal sink 230. The central channel 201 will be described in connection with FIG. The inner heater 220-1 and the outer heater 220-2 are arranged so as to communicate heat with the pack 200. The heater 220 is embedded and illustrated in the pack 200, but this is not necessary. Although it may be advantageous for the heater 220 to be entirely located on most of the pack 200, the distribution of the heater 220 over the surface 204 may vary in embodiments. The heat provided by the heater 220 will substantially control the temperature of the inner and outer portions 212 of the pack 200. In order to improve the accuracy of the heat control, the heat blocking unit 210 supports the thermal separation of the portions 212 and 214 from each other. The heater 220 is typically a resistance heater, but other types of heaters (eg, those utilizing a forced gas or forced liquid) may also be used.

An optional heat sink 230 may also be provided. The heat sink 230 produces a temperature below the typical operating temperature, for example, by flowing a heat exchange fluid at a controlled temperature through it, or by using a cooling device such as a Peltier cooler. Can be controlled. The thermal sink 230, if present, offers several advantages. One such advantage is to provide a reference temperature that all parts of the pack 200 will have in situations where heat is not provided by the heater 220. That is, the heater 220 can provide heat, but the heat typically propagates in all directions throughout the pack 200. When the heater 220 is located in a particular part of the pack 200, the heat generated by this heater does not simply spread throughout the pack 200 in all directions, but the heat from the heater 200 of the pack 200 is this heat. The heat sink 230 provides the ability to bring all parts of the pack 200 to a lower temperature, such as heating parts that locally surpass the properties of the heat sink 230. The thermal sink 230, if present, can be thermally and / or mechanically coupled to the pack 200 at multiple attachment points 222 (schematically shown in FIG. 3, but attachment points 222 are those shown in FIG. 3). May not be similar: see FIGS. 6A, 6B, and 6C). The mounting points 222 are advantageously numerous and evenly distributed around the surface 204 of the pack 200. The mounting points 222 provide substantially all of the heat communication between the pack 200 and the heat sink 230, and a large number and evenly distributed mounting points 222 are arranged so that the provided reference temperature is applied uniformly. Provided. For example, a pack 200 with a diameter of at least 10 inches may have 20 or more attachment points, and a pack 200 with a diameter of at least 12 inches may have at least 30 or much more attachment points.

A related advantage is that the thermal sink 230 responds to a relatively rapid temperature drop in adjacent parts of the pack 200 when the temperature setting of the heater 220 (eg, the current through the resistance wire) drops. It is possible to provide rapid heat sink performance. This makes it possible, for example, to place the workpiece 50 on the pack 200, to provide heat through the heater 220, and to realize rapid temperature stabilization of the workpiece 50. The benefit is that the system can be started quickly to maximize system throughput. Without heat communication that allows some heat to diffuse into the heat sink 230, the temperature reached at each part of the pack 200 will only drop as quickly as the other heat diffusion paths allow.

The heater 220 and the heat sink 230 are typically arranged to communicate heat with the pack 200 to a different degree. For example, it can be said that the heater 220 directly communicates with the pack 200, while the heat sink indirectly communicates with the pack 200. That is, the heater 220 is typically positioned to be thermally coupled to the pack 200 to a higher degree, and the heat sink 230 is positioned to be thermally coupled to the pack 200 to a lower degree (at least the pack 200). The degree of thermal connection with the heater 220 is lower than that of the heater 220). Further, since the heater 220 has sufficient heat generation performance so that the heat applied by the heater 220 can surpass the heat connection between the pack 200 and the heat sink 230, a part of the heat generated by the heater 200 is heat. The temperature of the inner portion 212 and the outer portion 214 of the pack 200 can be increased while diffusing through the sink 230. Therefore, the heat provided by the heater 220 can be diffused through the heat sink 230, though not immediately. In embodiments, packs are used to balance considerations such as temperature uniformity at each of the inner 212 and outer parts 214, rapid temperature stabilization, manufacturing complexity and cost, and overall energy consumption. The arrangement of the 200, the heater 220 and the thermal sink 230, and the degree of thermal coupling between them, can be adjusted according to the principles of this document.

Yet another advantage of the heat sink 230 is that it limits the heat generated by the heater 220 to the vicinity of the pack 200. That is, the thermal sink 230 may provide a thermal upper bound for such components in order 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 is provided by a cable-type heating element that is incorporated into the pack 200 and thus (optionally) the heat sink 230 to form a wafer chuck assembly. The embodiments designed, assembled and operated as disclosed herein allow for systematic temperature control of the edge region with respect to the central region of the workpiece (eg wafer) and are typically of the prior art. It facilitates processing using systematic center-to-edge temperature control, which is not feasible in the system.

FIG. 4 is a schematic cross-sectional view showing a part 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. 4 shows a portion of the wafer chuck near the cylindrical axis Z, but is not drawn to scale for easy understanding of the small features. The pack 200 is typically made of an aluminum alloy (eg, a well-known "6061" alloy type). The pack 200 is illustrated on the top surface 202 of the pack 200 so as to define a surface groove or channel 205 that connects to a central channel 201 centered about the Z axis. Atmospheric pressure (or gas pressure in a relatively high pressure plasma or low pressure deposition system, eg, about 10-20 Torr) urges the workpiece 50 (see FIGS. 1 and 2) to abut on the pack 200. A vacuum can be supplied to the central channel 201 to reduce the pressure in the channel 205 so as to provide good heat 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 figure of the inner resistance heater 220-1 and the description below apply equally to the outer resistance heater 220-2. The resistance heater 220-1 includes a cable heater 264 that is spiraled in a spiral pattern or other pattern within the pack 200. The cable heater 264 is arranged in the groove of the pack 200, and is assembled in the pack 200 by covering the groove (see FIG. 5). After assembling the cable heater 264 as the inner resistance heater 220-1 (and the second cable heater as the outer resistance heater 200-2), the pack 200 is assembled to the heat sink 230 using the fastener 270. The areas that provide mounting points for the fastener 270, both the pack 200 and the heat sink 230, are described in more detail below (see FIGS. 6A, 6B, and 6C), around the pack 200 and the heat sink. Arranged to control heat transfer characteristics to and from 230.

FIG. 5 schematically shows the lower side of the pack 200-1 in which the cable heaters 264-1 and 264-2 are internally mounted as the inner resistance heater and the outer resistance heater, respectively. The heat blocking portion 210 is a recess defined on the bottom surface 204 of the pack 200-1 and forms a radial boundary between the inner portion 212 and the outer portion 214 of the pack 200 (see FIGS. 2 and 3). The cable heater 264-1 extends from the connector 262-1 along a substantially spiral path laid out to transfer heat uniformly to all areas of the inner portion 212. The heater cap 266-1 is shown as a shaded portion of the spiral path and is connected in place after the cable heater 264-1 is placed in place. In one embodiment, the heater cap 266-1 is a fillet preformed in the shape of a groove into which the cable heater 264-1 is mounted and is fixed in place. The heater cap 266-1 can be welded in place using, for example, electron beam welding, but can also be secured with an adhesive or filler (eg, epoxy). The fillet is preferably welded in place along at least a portion of the arc length of the cable heater, but does not need to be welded along the entire arc length (eg, cable heater 264-2). It does not have to be partially welded to avoid damage to the underlying structure). In one embodiment, the heater cap 266-1 is welded in place using electron beam welding. The cold-to-hot transition point 265-1 is a conductive wire in the cable heater 264-1 that extends from the connector 262-1 and is hidden under the heater cap 266-1. It shows the place to connect to the resistant material in the cable heater 264-1. Therefore, almost no heat is generated between the connector 262-1 and the transition point 265-1, but the cable heater 264-1 past the transition point 265-1 generates a uniform amount of heat per unit length. The cable heater 264-2 is laid out so that heat is uniformly transferred from the connector 262-2 first radially outward from the central region of the pack 200 (which is connected through the shaft of the wafer chuck) and then to the outer portion 214. It extends along a nearly circular path that has been made. The heater cap 266-2 is illustrated as a shaded portion of the spiral path and is connected in place after the cable heater 264-2 has been placed in place. In one embodiment, the heater cap 266-2 is a fillet preformed in the shape of a groove into which the cable heater 264-2 is mounted and is welded in place using electron beam welding. Like the heater cap 266-1, the fillet forming the heater cap 266-1 is preferably welded in place along at least a portion of its arc length, but along its entire arc length. It does not need to be welded. The thermal transition point 265-2 extends from the connector 262-2 and the conductive wire in the cable heater 264-2 hidden under the heater cap 266-2 is a resistor in the cable heater 264-2. Indicates where to connect to the sex material. Therefore, almost no heat is generated between the connector 262-2 and the transition point 265-2, but the cable heater 264-2 past the transition point 265-2 generates a uniform amount of heat per unit length. FIG. 5 also shows a set of protrusions 268. The protrusions 268 are protrusions from the bottom surface 204 such that they protrude from the plane of the figure (eg, so that these protrusions face the heat sink 230: see FIG. 3). The protrusion 268 forms a place for the attachment point 222 and cooperates with the fastener 270 (FIG. 4), but the protrusion 268 will be described in more detail in connection with FIGS. 6A, 6B.

FIG. 6A is a detailed view of a portion of the pack 200 and optional thermal sink 230 shown in FIG. 4 near the fastener. The pack 200 includes a cable heater 264 sealed within the pack 200 using a heater cap 266, as described above in connection with FIG. As further mentioned above, the optional heat sink 230 may provide a reference temperature for the pack 200, but the heat sink 230 and the pack 200 have a degree of heat communication between the pack 200 and the heater 220. It is desirable to arrange it so that it is less than the degree. Therefore, mounting points that allow heat communication between the heat sink 230 and the pack 200 are advantageously arranged to manage the heat transfer characteristics between them. For example, the pack 200 and the thermal sink 230 may be manufactured such that there is a lateral gap between the protrusion 268 and the thermal sink 230, as shown. That is, the thickness of the heat sink 230 decreases in the thinning region 235 near the protrusion 268, the lateral width of the thinning region 235 is wider than the lateral width of the protrusion 268, and the protrusion 268 and the heat sink 230 A lateral gap 286 is formed with the entire thickness portion. The heat sink 230 forms an opening for the fastener 270 to pass through, the protrusion 268 defines an internal void, and a portion of this internal void can be a female thread through which the fastener 270 connects. However, the void 275 may be longer than the fastener 270, for example, as shown in FIG. 6A, in order to limit the heat transfer from the pack 200 through the protrusions 268. Physical points for attaching the pack 200 to the heat sink 230 include protrusions 268, fasteners 270, and a pair of washers 272. The main heat transfer path near the fastener 270 is indicated by the solid wavy arrow 278 in FIGS. 6A and 6B, while the secondary (eg, radiative) heat transfer path is designated as the dotted wavy arrow 279. Shown. Void 231 will be described later in relation to FIG. 6C.

FIG. 6B schematically illustrates one embodiment of the uncompressed wave washer 272. While it is possible to utilize flat washers in some embodiments, wave washers are advantageous in other embodiments. The azimuthally corrugated washer 272 is advantageous in that the pack 200 can be connected to the heat sink 230 at multiple points without being overly constrained to either the pack 200 and the heat sink 230. Is. That is, in a mathematical sense, considering that a plane is formed by only three points, the number of attachment points between the pack 200 and the heat sink 230 exceeds 3, so that the protrusions of the heat sink 230 and the pack 200 are projected. An overly constrained system is formed that imposes a very strict mechanical tolerance on the flatness of the attachment point between and the 268. The use of wave washers 272 can loosen the tolerance for flatness in such features. This is because the washer 272 does not require the attachment points of the corresponding components to be located along a perfectly flat surface, but rather provides mechanical connectivity throughout the compression range. Similarly, the compression range of the wave washer 272 allows for local thermal expansion in the pack 200 and / or the thermal sink 230. The wave washer 272 has an uncompressed thickness 273 that is at least twice the compressed thickness 274 in some embodiments, and an uncompressed thickness 273 that is at least five times the compressed thickness 274 in other embodiments. Has. The washer 272 is shown in a flat cross-sectional shape in FIG. 6A for the sake of clarity, but upon reading and understanding this disclosure, the Fastener 270 is sufficient to flatten the wave washer 272 completely. It will be appreciated that may not be tightened, thereby preserving some, if not all, of the wave shape with the wave washer 272 attached. Also, the wave washer 272, when in use, is localized from the protrusion 268 to the local apex where the washer 272 contacts the protrusion 268, and then laterally within the washer 272, where the washer 272 contacts the thermal sink 230. By transferring heat to the valleys, the heat transfer between the protrusions 268 and the heat sink 230 is reduced. The washer 272 can be made of, for example, beryllium copper. Some embodiments utilize two washers 272, one on each side of the thermal sink 230, as shown, while other embodiments typically utilize protrusions 268 and heat. Only a single washer 272 with the sink 230 is used.

FIG. 6C is a bottom view of the vicinity of the fastener 270 as viewed from below. In FIG. 6C, the dashed lines 6A-6A indicate the cross-sectional plane shown in FIG. 6A. The thermal sink 230 forms one or more voids 231 in the thinning region 235 near the fastener 270. The void 231 further reduces the heat communication between the pack 200 and the heat sink 230. The number and arrangement of voids 231 in the thermal sink 230 shown in FIG. 6C is not necessary. It will be appreciated by reading and understanding this disclosure that the size, number and arrangement of voids 231 may be modified to adjust the thermal coupling properties between the thermal sink 230 and the pack 200. For example, by providing a second set of voids 231 radially outward from the voids 230 shown in FIG. 6C to lengthen the thermal path between the protrusions 268 and the body of the thermal sink 230, and illustrated. It is also possible to further reduce the thermal coupling between the thermal sink 230 and the pack 200 by staggering the additional pairs with respect to the voids 231 provided. Further, FIG. 6C shows that the outer edge of the thinning region 235 coincides with the outer edge of the void 231, but this is not always the case. Certain embodiments may have voids 231 well within the edges of the thinning region 235 or partially extending to the heat sink 230 outside the thinning region 235. Similarly, the number, arrangement, and wall thickness of the protrusions 268 can be modified to achieve higher or lower heat conduction between the pack 200 and the heat sink 230.

A further advantage of providing at least one thermal barrier 210 that intersects the top surface of the pack 200 is to prevent certain mechanical features from causing thermal anomalies on the surface of the pack 200. It can be placed at least partially within the heat shield. For example, a wafer chuck generally lifts the wafer a short 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 lifted). Or provide a lift pin that can be used to facilitate (using other devices). However, the lift pins typically recede into the holes in the chuck, and such holes and lift pin structures can locally affect the wafer temperature during processing. When the heat shield intersects the top surface of the pack 200, there is already a place where such a mechanism is arranged without causing thermal anomalies.

FIG. 7 schematically shows a part of a wafer chuck having a lift pin mechanism 300 for controlling the lift pin 310, which is arranged in the heat blocking unit 210. The heater 220 and the optional heat sink 230 are also partially illustrated. The cross-sectional plane shown in FIG. 7 passes through the center of the mechanism 300, so that the components of the mechanism 300 are in the lower part of one of the heat blocking portions 210. Since the pack 200, the heat shield 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 plane shown, the mechanism 300 is arranged inside. The heat shield 210 continues along its arc through the pack 200 (see FIG. 8). Further, the lift pin mechanism 300 is limited to a considerably narrow azimuth angle with respect to the central axis of the pack 200 (also see FIG. 8). That is, if the cross-sectional plane is cut at a certain distance in front of or behind the plane shown in FIG. 7, the bottom surface of the pack 200 is continuous along the same plane shown as the bottom surface 204 in FIG. 7, and heat is generated. The sink 230 should have been contiguous 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. 7 shows the lift pin 310 in a retracted position where the lift pin 310 does not cause thermal anomalies on the surface of the pack 200.

FIG. 8 schematically shows a plan view of a three-lift pin configuration in which the lift pin 310 is arranged in the heat blocking portion 210. FIG. 8 is not on scale. In particular, the heat cutoff section 210 has been enlarged to clearly show the lift pin mechanism 300 and the lift pin 310. Since the lift pin 310 recedes considerably below the average surface of the pack 200 in the heat shield 210, it does not cause a spatial thermal anomaly during the process. Therefore, the portion of the work piece being processed at the lift pin 310 (eg, a particular integrated circuit located at the corresponding location on the semiconductor wafer) coincides with the treatment at the other location of the work piece. Go through processing.

FIG. 9 is for processing a wafer or other workpiece (hereinafter, simply referred to as “product wafer” for convenience, but this concept can be applied to workpieces other than wafers). It is a flow chart of the method 400. 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 equipment can make it possible on its own. The first step 420 of 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 performed in an equipment or process environment that unintentionally or uncontrollably causes the associated center-to-edge process variation (“uncontrolled variation”). , This is not necessary. Also, typically, another center-to-edge process variation (“Control”) is provided through a thermal management technique that allows systematic control of the central and edge portions of the product wafer and provides the corresponding reverse process variation. The other step is performed in equipment as described in this document so that "variation") is introduced. However, uncontrolled variation and controlled variation can occur in any order. That is, 420 may result in either uncontrolled or controlled variation, and 440 may result in the other of uncontrolled and controlled variation. 10 and 11 provide additional guidance to those skilled in the art to enable useful operation of Method 400.

FIG. 10 is a flow diagram of Method 401, including (but not limited to) Step 420 of Method 400. All of 410-417, and 422 shown in FIG. 10 are considered optional, but in embodiments they may help to achieve useful wafer processing results in the practice of method 400.

Step 410 sets the equipment characteristics associated with the first center-to-edge process variation that occurs at 420. For example, if the 420 is expected to result in control variation, the 410 may include providing equipment parameters such as a heater setting that provides controlled center-to-edge temperature variation. Equipment as described in FIGS. 2-8 of this document helps to provide controlled center-to-edge temperature fluctuations. Step 412 measures the equipment characteristics associated with the first center-to-edge process variation. Process knowledge over time as to what equipment settings or measured equipment characteristics successfully generate known center-to-edge process variation (or provide at least stable process variation, if not intentionally). Can be obtained as a target. Taking this process knowledge into account, method 401 can optionally revert from 412 to 410 to adjust the equipment characteristics if it is believed that the equipment characteristics measured at 412 could be improved. Step 414 processes one or more test wafers subject to first center-to-edge process variation. Step 416 is the test wafer (s) processed in step 414 to measure one or more characteristics of the first center-to-edge process variation. Method 401 can optionally return from 416 to 410 to adjust the equipment characteristics in light of the center-to-edge process characteristics measured at 416. If the test wafer is processed at 414, at 418 the test in the second process (eg, the process later performed at 440) may be optionally 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 at the same time as the product wafer (eg, a so-called "batch" process in which the first process immerses the wafer cassette in a liquid bath. If so, the wafer set is processed at a time in one ample, diffusion furnace, or deposition chamber, etc.).

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 and, as will be described later, for equipment process control, for correlation with product wafer yield or performance, and /. Alternatively, generate data for use in correlating with information around step 440.

FIG. 11 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. 11 are considered optional, but in embodiments they may help to achieve useful wafer processing results in the practice of method 400.

Step 430 sets the 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 as described in FIGS. 2-8 of this document helps to provide controlled center-to-edge temperature fluctuations. Step 432 measures the equipment characteristics associated with the second center-to-edge process variation. Taking into account the process knowledge described above, method 402 can optionally revert 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 subject to a second center-to-edge process variation. The test wafer (s) processed in 434 may include one or more test wafers that have not undergone the first process step of 418 above. Step 436 measures one or more characteristics of the second center-to-edge process variation on the test wafer (s) processed in 434. Taking into account the process knowledge already acquired, method 402 can optionally revert from 436 to 430 to adjust the equipment 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 wafers. Step 442 measures one or more first center-to-edge characteristics on the product wafer and, as described above, for equipment process control, for correlation with product wafer yield or performance, and /. Alternatively, generate data for use in correlation with information around 420. Such measurements can be made on any test wafer that has been processed in parallel with the product wafer, but in any case, 442 generally does not further alter any conditions present on the product wafer. No. That is, the results of 420 and 440 will be finalized on the product wafer at the end of 440, regardless of whether further testing is performed.

Although some embodiments have been described, those skilled in the art will appreciate that various modifications, alternative structures, and equivalents can 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 invention. Therefore, the above description should not be construed 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 the present disclosure. Therefore, the characteristics of the chucks in this document as "wafer chucks" for holding "wafers" are equivalent to those for holding any type of workpiece, and " It should be understood that a "wafer processing system" is similarly equivalent to a processing system.

When a range of values is provided, each intervening value between the upper and lower bounds of that range is also explicitly disclosed up to one tenth of the lower bound unit, unless otherwise stated in the context. I want to be understood. Each of the narrower ranges between any specified or intervening value in one defined 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, and if any of the limits are within the narrower range, then any of the limits. Each range, if not within the narrower range, or if both limits are within the narrower range, is also subject to any limits explicitly excluded within the defined range. , Is included in 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 accompanying claims, the singular "one (a, an)" and "the" include multiple referents unless otherwise specified in the context. Thus, for example, a reference to "a process" includes a plurality of such processes, and a reference to "the electrode" includes one or more electrodes, and to those skilled in the art. Including references to its known equivalents, and so on. The terms "comprise / comprising" and "include / include" are also used in this specification and in the claims below, as defined features, integer values, components, Or, it is intended to clarify the existence of a step, but does not exclude the existence or addition of one or more other features, integer values, components, steps, actions, or groups.

Claims (17)

A work piece holder that positions the work piece for processing.
A substantially cylindrical pack , characterized by having a cylindrical shaft, a pack radius around the cylindrical shaft, and a substantially flat top surface, the direction parallel to the top surface is defined as the lateral direction. With a pack ,
A first heating device arranged to communicate heat with the radial inner portion of the pack.
A second heating device arranged to communicate heat with the radial outer portion of the pack, wherein the first heating device and the second heating device can be individually controlled with respect to each other. With a heating device
It has a heat sink arranged to communicate with the pack.
It said second heating device and the first heating device, each degree of thermal communication with the pack, rather higher than the degree of thermal communication with the heat sink and the pack,
A plurality of attachment points between the heat sink and the pack provide substantially all of the heat communication between the heat sink and the pack, and for at least one of the attachment points.
The pack forms a protrusion facing the heat sink,
The heat sink forms an opening and
A workpiece holder through which the fastener passes through the opening and is connected to the inside of the protrusion. A work piece holder that positions the work piece for processing.
A substantially cylindrical pack characterized by a cylindrical shaft and a substantially flat top surface, comprising a pack defining two radial heat barriers.
The first of the heat shields is characterized as a radial recess that intersects the bottom of the pack at a first radius and extends from the bottom to at least half the thickness of the pack. Attached,
The second of the heat shields intersects the top surface of the pack at a second radius greater than the first radius, and from the top surface to at least half the thickness of the pack. Characterized as an extending, radial recess,
The first heat shield and the second heat shield define a boundary between the radial inner portion of the pack and the radial outer portion of the pack.
The pack
A first heating device embedded in the radial inner portion of the pack,
It comprises a second heating device embedded within the radial outer portion of the pack.
The workpiece holder is a heat sink that extends substantially below the bottom surface of the pack, allowing heat exchange fluid to flow through an internally defined channel to maintain a reference temperature for the pack. Equipped with a metal plate, further equipped with a heat sink,
The thermal sink is mechanically and thermally connected to the pack at a plurality of attachment points, which are the thermal communication between each of the first heating device and the second heating device and the pack. To provide less than a degree of heat communication between the heat sink and the pack ,
A workpiece holder in which the plurality of attachment points between the heat sink and the pack provide substantially all of the heat communication between the heat sink and the pack. At least one of the first heating device and the second heating device comprises a cable heater arranged in a groove defined in the bottom surface of the pack.
Further, a heater cap arranged in the groove to hold the cable heater in place and fixed to the pack along at least a portion of the arc length of the cable heater. The workpiece holder according to claim 1 or 2. The workpiece holder according to claim 1 or 2 , wherein the pack has a diameter of at least 12 inches and the plurality of attachment points include at least 30 attachment points. At at least one of the mounting points
The protrusions define the first lateral width and
The heat sink defines a cavity facing the bottom surface of the pack, the cavity being partially bounded by a thinned portion of the heat sink, which is reduced in thickness around the perforation. to a moiety which, the so lateral clearance between the projection and the side surface of the cavity is present, the size of the cavity of the first lateral wide wide second transverse direction than is to view a constant, workpiece holder according to claim 1. In order to limit heat transfer through the heat path extending from the pack and reaching the heat sink through the fastener and the material of the heat sink surrounding the fastener, the heat sink is placed in the thinned portion. The workpiece holder according to claim 5, wherein one or a plurality of voids adjacent to the opening are defined. Further provided with a wave washer disposed around the fastener between the heat sink and the protrusion.
The wave washer, have at least 2 times the net uncompressed thickness of the compressed thickness, wherein the fastener, local thermal expansion by being partially tightened without having to completely flatten the wave washer effect its permissible operating, the workpiece holder according to claim 1. Said heat sink comprises a metal plate defining one or more fluid channels, in order to determine the reference temperature of the heat sink, the heat exchange fluid flows through the pre-Symbol Fluid channels, according to claim 1 or 2 Work piece holder described in. The pack, characterized by packs thickness,
Before Symbol substantially cylindrical pack of defining one or more radial heat shield unit between the radially inner portion and said radially outer portion of the pack,
Each heat shield is characterized as a radial recess that intersects at least one of the top and bottom surfaces of the substantially cylindrical pack.
The depth of the heat shield extending from the top or bottom of the pack to at least half the thickness of the pack.
The workpiece holder according to claim 1, which is symmetrically arranged with respect to the cylindrical axis and is characterized by a heat blocking radius, which is at least half of the pack radius. The workpiece holder according to claim 1, wherein the protrusion is formed integrally with the pack and protrudes from the bottom surface of the pack to the heat sink. The workpiece holder according to claim 1, wherein the fastener is coupled to the female screw of the protrusion. The workpiece holder according to claim 1 or 2, wherein the mounting points are substantially evenly distributed over the radial inner and outer portions of the pack. A method of controlling the spatial temperature distribution of a work piece by using the work piece holder according to claim 1.
By flowing the temperature of the heat exchange fluid is controlled through channels in the heat sink to pack thermal communication of the substantially cylindrical, and providing a reference temperature for said packs,
By actuating the arranged first heating device to thermal communication with the radially inner portion of the pack, the high standards to a first temperature than the temperature, increasing the temperature of said radially inner portion of the pack To let and
By actuating the placed second heating device to thermal communication with the radially outer portion of the pack, the high standards to a second temperature above the temperature, increasing the temperature of said radially outer portion of the pack To let and
A method comprising placing the work piece on the pack. Providing said reference temperature for said substantially cylindrical pack, further comprising linking the said heat sink the substantially cylindrical pack in said plurality of attachment points,
Providing the reference temperature for the substantially cylindrical pack increases the thermal resistance between the heat sink and the pack.
Adjacent to each of the mounting points, providing voids in the heat sink, and
13. The method of claim 13 , comprising at least one of placing a wave washer between the heat sink and the substantially cylindrical pack. Raising the temperature of said radially inner portion of the pack, and, raising the temperature of said radially outer portion of the pack comprises passing a current through the cable heater, the method according to claim 13 .. By providing one or more thermal barriers between the radial inner portion and the radial outer portion in the pack, the radial inner portion of the pack and the radial outer portion of the pack Further includes providing thermal resistance between
Each of the heat shields is defined as a radial recess that intersects at least one of the top and bottom surfaces of the pack.
13. The method of claim 13 , wherein the radial recess is characterized by a depth that exceeds half the thickness of the pack. Providing the one or more heat barriers between the radial inner portion and the radial outer portion in the pack comprises providing a radial recess that intersects the upper surface of the pack.
16. The 16 . the method of.

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