Temperature controlled / electrically biased wafer periphery

Abstract

A system and method for etching a workpiece in a uniform manner is disclosed. The system includes a semiconductor processing system that generates a ribbon ion beam and a workpiece holder that scans the workpiece through the ribbon ion beam. The workpiece holder includes a portion that extends beyond the workpiece, called a halo. The halo can be independently heated to compensate for etch rate non-uniformities. In some embodiments, the halo can be independently biased such that its potential is different than the potential applied to the workpiece. In certain embodiments, the halo can be divided into multiple thermal zones that can be separately controlled. In this manner, various etch rate non-uniformities can be addressed by controlling various thermal potentials and / or temperatures of the halo.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 17 / 167,416, filed February 4, 2021, the disclosure of which is incorporated by reference in its entirety herein.

[0002] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to systems and methods for improving etch rate uniformity, and more particularly, to systems and methods for improving etch rate uniformity of a workpiece scanned through a ribbon ion beam. [Background technology]

[0003] Ion beams may be used to implant dopants into a workpiece, such as a silicon substrate, etch material of the workpiece, or amorphize the workpiece. These ion beams may be generated using a semiconductor processing system that includes an ion source that produces ions of a desired species. In certain embodiments, these ions are extracted and manipulated by components that select the desired species and direct the ions toward the workpiece. In other embodiments, an ion source is positioned proximate to the workpiece and ions are drawn from the ion source toward the workpiece.

[0004] In some implementations, it may be necessary to tightly control the uniformity of various parameters. For example, in certain applications, it may be desirable to have an etch rate within 3-5% (three sigma value) across the wafer (WiW) or better. However, beam current variations across the wafer and other phenomena can make this difficult to achieve. can be difficult.

[0005] For example, it is common for ribbon ion beams to have non-uniform beam current in the X-direction, especially at both ends of the ribbon beam.

[0006] Additionally, the workpiece may be disposed on a workpiece holder that passes through the ribbon ion beam. The workpiece holder may include a portion that extends beyond the workpiece. This portion may be referred to as a surround or halo. Any electrical or thermal discontinuity between the workpiece and the halo may result in variations in etch rate uniformity.

[0007] Therefore, it would be beneficial to have a system and method for achieving a desired etch rate uniformity using a scanned ribbon ion beam. Additionally, it would be beneficial to have a system that is easily adaptable to a variety of etchant species. Summary of the Invention

[0008] A system and method for etching a workpiece in a uniform manner is disclosed. The system includes a semiconductor processing system that generates a ribbon ion beam and a workpiece holder that scans the workpiece through the ribbon ion beam. The workpiece holder includes a portion that extends beyond the workpiece, called a halo. The halo may be independently heated to compensate for etch rate non-uniformities. In some embodiments, the halo may be independently biased such that its potential is different than the potential applied to the workpiece. In certain embodiments, the halo may be divided into multiple thermal zones that may be separately controlled. In this manner, various etch rate non-uniformities may be compensated for by the various thermal zones of the halo. zone This can be addressed by controlling the potential and / or temperature.

[0009] According to one embodiment, an etching system is disclosed. The etching system includes a semiconductor processing system for generating a ribbon ion beam, a workpiece holder, a halo disposed around the workpiece holder, and a scanning motor for moving the workpiece holder through the ribbon ion beam, where the halo includes a resistive heater for modifying a temperature of the halo. In certain embodiments, the halo includes a conductive frame and a protective cover disposed on the conductive frame, and the resistive heater is disposed in or on the protective cover. In certain embodiments, the resistive heater is disposed on an outer surface of the protective cover facing the conductive frame. In some embodiments, the etching system includes a temperature sensor disposed on the halo for monitoring a temperature of the halo. In certain embodiments, the halo includes a conductive frame and a protective cover disposed on the conductive frame, and includes a halo bias power supply for biasing the conductive frame at a voltage different from a voltage applied to the workpiece holder. In some embodiments, the halo bias power supply is referenced to the workpiece holder such that the halo maintains a constant voltage offset from the workpiece holder. In some embodiments, the halo is electrically isolated from the workpiece holder using an insulating material.

[0010] According to another embodiment, an etching system is disclosed. The etching system includes a semiconductor processing system for generating a ribbon ion beam, a workpiece holder, a halo disposed around the workpiece holder, and a scanning motor for moving the workpiece holder through the ribbon ion beam. In this case, the halo includes multiple thermal zones to compensate for both radial and linear etch rate non-uniformities. In some embodiments, the halo includes a frame and a protective cover disposed on the frame, and a resistive heater is disposed in or on the protective cover. In certain embodiments, the resistive heater is disposed on an outer surface of the protective cover facing the frame. In some embodiments, the halo is divided into multiple thermal zones. In some further embodiments, the multiple thermal zones may be independently controlled. In some embodiments, the etching system includes a thermal controller. The thermal controller includes multiple power sources in communication with the multiple thermal zones, and a controller in communication with the thermal controller. In this case, the workpiece type and etch species are input to the controller, and the thermal controller provides power to the multiple thermal zones to achieve a desired temperature profile. In certain embodiments, the etching system includes a temperature sensor disposed in the at least one thermal zone for monitoring a temperature of the at least one thermal zone.

[0011] According to another embodiment, an etching system is disclosed. The etching system includes a semiconductor processing system for generating a ribbon ion beam, a workpiece holder, a halo disposed around the workpiece holder, the halo including a conductive frame and a protective cover disposed on the conductive frame, a scan motor for moving the workpiece holder through the ribbon ion beam, and a halo bias power supply for biasing the conductive frame at a voltage different from a voltage applied to the workpiece holder. In some embodiments, the halo bias power supply is referenced to the workpiece holder such that the halo maintains a constant voltage offset from the workpiece holder. In some embodiments, the halo is electrically isolated from the workpiece holder using an insulating material. In certain embodiments, the conductive frame is divided into multiple conductive regions, where the voltage applied to each conductive region is independently controlled. In certain embodiments, the etching system includes a controller in communication with the halo bias power supply, where the workpiece type and etch species are input to the controller and the halo bias power supply provides power to the conductive frame to achieve a desired change in edge etch rate.

[0012] For a better understanding of the present disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference. [Brief description of the drawings]

[0013] [Figure 1] 1 illustrates a semiconductor processing system according to one embodiment. [Figure 2A] 2A-2C show three embodiments that use a halo bias power supply. [Figure 2B] 2A-2C show three embodiments that use a halo bias power supply. [Figure 2C] 2A-2C show three embodiments that use a halo bias power supply. [Diagram 3] 1 illustrates a resistive heater according to one embodiment. [Figure 4]1 is a first embodiment of a halo having multiple thermal zones. [Figure 5A] 5A-5E show etch rate maps for various etch species and workpiece types. [Figure 5B] 5A-5E show etch rate maps for various etch species and workpiece types. [Figure 5C] 5A-5E show etch rate maps for various etch species and workpiece types. [Figure 5D] 5A-5E show etch rate maps for various etch species and workpiece types. [Figure 5E] 5A-5E show etch rate maps for various etch species and workpiece types. [Figure 6A] 6A-6E show the heating patterns of the halo of FIG. 4 for various etch rate maps. [Figure 6B] 6A-6E show the heating patterns of the halo of FIG. 4 for various etch rate maps. [Figure 6C] 6A-6E show the heating patterns of the halo of FIG. 4 for various etch rate maps. [Figure 6D] 6A-6E show the heating patterns of the halo of FIG. 4 for various etch rate maps. [Figure 6E] 6A-6E show the heating patterns of the halo of FIG. 4 for various etch rate maps. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As mentioned above, the present system can be used to improve etch rate uniformity in systems that employ a workpiece that is scanned through a ribbon ion beam.

[0015] The semiconductor processing system 1 comprises an ion source including an ion source chamber 100 comprised of a number of chamber walls 101. In certain embodiments, one or more of the chamber walls 101 may be constructed of a dielectric material, such as quartz. An RF antenna 110 may be disposed on an outer surface of a first dielectric wall 102. The RF antenna 110 may be powered by an RF power supply 120. Energy provided to the RF antenna 110 is radiated into the ion source chamber 100 to ionize a feed gas introduced via a gas inlet 130.

[0016] In other embodiments, the ion source may be an indirectly heated cathode (IHC) ion source, a capacitively coupled plasma source, or another type of source.

[0017] One chamber wall, called the extraction plate 104, includes an extraction aperture 105 through which the ion beam 106 may exit the ion source chamber 100. The ion beam 106 may be much wider in the horizontal direction (also called the X-direction) than in the height direction. An ion beam with these characteristics may be called a ribbon ion beam. The extraction plate 104 may be constructed of a conductive material such as titanium, tantalum, or another metal. The extraction plate 104 may be over 300 millimeters wide. Additionally, the extraction aperture 105 may be wider in the X-direction than the diameter of the workpiece 10. The extraction plate 104 may be biased with an extraction voltage. In other embodiments, the extraction plate 104 may be grounded.

[0018] In addition to the semiconductor processing system 1, there is a workpiece holder 155. The workpiece holder 155 may be located proximate to the extraction aperture 105. For example, the workpiece holder 155 may be between 0 and 25 cm from the extraction aperture 105. In certain embodiments, the workpiece holder 155 may be within about 1 cm of the extraction aperture 105.

[0019] The workpiece 10 may be placed on a workpiece holder 155. The workpiece holder 155 is scanned using a scan motor 160 that moves in a vertical direction 171, also referred to as the Y direction. Thus, the workpiece holder 155 is configured such that there is relative vertical movement between the ion beam 106 and the workpiece holder 155.

[0020] The workpiece holder 155 includes an electrostatic clamp that holds the workpiece 10. The electrostatic clamp uses electrostatic forces to hold the workpiece to the workpiece holder 155. The electrostatic clamp may include a base, a dielectric top surface, and multiple electrodes disposed between the base and the dielectric top surface. Various voltages may be applied to the electrodes to generate the desired electrostatic force.

[0021] A halo 165 surrounds the electrostatic clamp and workpiece 10 and has an opening in its center corresponding to the location of the workpiece holder 155. The halo 165 includes a frame 168 that may be constructed of a conductive material such as metal. The frame 168 may be made of titanium, aluminum, or another material. In certain embodiments, the frame 168 may be nickel-plated aluminum, anodized aluminum, or nickel. In certain embodiments, the frame 168 may be rectangular with a circular cutout to accommodate the workpiece holder 155. For example, the frame 168 may be about 600 mm wide, about 1000 mm high, with a circular opening with a diameter of about 300 mm. In other embodiments, the frame 168 may be circular or another shape.

[0022] Additionally, the halo 165 may include a protective cover 166. The protective cover 166 may be disposed on a front surface of the frame 168. The protective cover 166 protects the frame 168 from exposure to ions, extends the life of the frame 168, and minimizes contamination of the workpiece 10. The protective cover 166 may be a dielectric material or a silicon substrate attached to the front surface of the frame 168. In one particular embodiment, a number of silicon tiles are disposed on the frame 168 and act as the protective cover 166. The protective cover 166 may be of any desired thickness, such as about 3 mm. The protective cover 166 may be sized to cover the entirety of the frame 168.

[0023] The workpiece holder 155 may be biased using a workpiece bias power supply 170. In certain embodiments, the output from the workpiece bias power supply 170 is a pulsed DC voltage having a frequency between 5 kHz and 50 kHz and an amplitude of 100 to 5000 volts.

[0024] Halo 165 may be independently biased using halo bias power supply 175. For example, frame 168 may be in communication with halo bias power supply 175. The output from workpiece bias power supply 175 may also be a pulsed DC voltage having a frequency between 5 kHz and 50 kHz and an amplitude of 100 to 5000 volts.

[0025] In certain embodiments, halo bias power supply 175 is referenced to workpiece bias power supply 170, such that halo 165 is at a constant voltage offset from workpiece holder 155. For example, in this embodiment, the output of halo bias power supply 175 may be set to a constant DC voltage.

[0026] For example, Figures 2A-2C show three different embodiments. Figure 2A shows one embodiment where the halo 165 is always at the same voltage as the workpiece holder 155. This may be achieved by setting the halo bias power supply 175, referenced to the workpiece bias power supply 170, to 0 volts. In Figure 2B, the halo 165 is always positively offset relative to the workpiece holder 155. This may be achieved by setting the halo bias power supply 175, referenced to the workpiece bias power supply 170, to a positive voltage. In Figure 2C, the halo 165 is always negatively offset relative to the workpiece holder 155. This may be achieved by setting the halo bias power supply 175, referenced to the workpiece bias power supply 170, to a negative voltage. The halo bias power supply 175 may provide a voltage between -500V and +500V relative to the workpiece holder 155. In this manner, the bias of the halo 165 relative to the ion source chamber 100 is, in some embodiments, the sum of the voltages supplied by the halo bias power supply 175 and the workpiece bias power supply 170 .

[0027] In other embodiments, the halo bias power supply 175 may be referenced to ground and the output of the halo bias power supply 175 may be in phase with the workpiece bias power supply 170, so that the pulses from the two power supplies are synchronized. Furthermore, in certain embodiments, the output of the halo bias power supply 175 differs from the workpiece bias power supply 170 only during these pulses.

[0028] Although in the above disclosure the output from the workpiece bias power supply 170 is described as being a pulsed DC voltage, it should be understood that the workpiece bias power supply 170 may be constant. In this case, the extraction voltage power supply that biases the extraction plate 104 provides the pulsed DC output. In this embodiment, the halo bias power supply 175 may maintain a constant voltage.

[0029] In order to apply different voltages to the workpiece holder 155 and the halo 165, there may be an electrical insulating material 167 between these two components, electrically insulating the workpiece holder 155 from the frame 168. A material such as PEEK may be used to provide this electrical insulation.

[0030] Note that if the frame 168 and the workpiece holder 155 are always maintained at the same voltage, then the electrically insulating material 167 may not be utilized.

[0031] During the pulses, the voltage applied to the workpiece holder 155 is more negative than the voltage applied to the extraction plate 104. In other words, when the extraction plate 104 is grounded, the workpiece bias power supply 170 generates negative pulses. During these negative pulses, positive ions are attracted from within the ion source chamber 100 to the workpiece 10. When the extraction plate 104 is positively biased, the workpiece bias power supply 170 generates less positive or negative pulses. Thereby, during these pulses, positive ions are attracted from within the ion source chamber 100 to the workpiece 10.

[0032] Further, although FIG. 1 illustrates a single halo bias power supply 175 in certain embodiments, the halo 165 may be divided into several conductive regions. Each conductive region may then be independently controlled. For example, the frame 168 may be multiple conductive structures separated from one another using electrically insulating material 167. Thus, in this embodiment, certain portions of the halo 165 may be at a higher voltage than the workpiece holder 155, while other portions of the halo 165 may be at the same voltage or a lower voltage than the workpiece holder 155. Further, in this embodiment, certain portions of the halo 165 may be at a lower voltage than the workpiece holder 155, while other portions of the halo 165 may be at the same voltage or a higher voltage than the workpiece holder 155. As described below, the selection of the voltage applied to each segment of the halo 165 may be based on the etch species employed.

[0033] A thermal controller 190 may also be in communication with halo 165. Thermal controller 190 may include multiple power supplies that provide voltage or current to each of multiple thermal zones within halo 165, as described in more detail below.

[0034] A controller 180 may be in communication with the workpiece bias power supply 170, the halo bias power supply 175, the workpiece holder 155, the thermal controller 190, and other components. The controller 180 may include a processing unit 181, such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing unit. The controller 180 may also include a non-transitory storage element 182, such as a semiconductor memory, a magnetic memory, or another suitable memory. The non-transitory storage element 182 may include instructions 183 and other data that enable the controller 180 to perform the functions described herein. The controller 180 may control the movement of the workpiece holder 155 via the scan motor 160. The controller 180 may control the temperature and voltage of the halo 165 via the thermal controller 190 and the halo bias power supply 175, respectively.

[0035] There can be two types of etch rate non-uniformity. The first, referred to as radial non-uniformity, is the result of discontinuities at the edges of the workpiece. These discontinuities can be chemical, thermal, or electrical. For example, as described with respect to FIG. 1, there can be a halo 165 around the workpiece 10, comprising a frame 168 and a protective cover 166. If the material used to construct the halo 165 is more resistant to chemical etching than the workpiece, there can be an excess of etching species available at this interface, leading to faster etching of the outer edge of the workpiece. Conversely, if the material used to construct the halo 165 is less resistant to chemical etching than the workpiece, the halo 165 can act as a sink, leading to a shortage of etching species available at this interface, leading to slower etching of the outer edge of the workpiece. If the dielectric constant of the halo 165 is different from the workpiece, there can be distortions of the electric field at the edge of the workpiece. This distortion can attract or repel ions from the edge of the workpiece 10 as the extraction bias is pulsed. Additionally, if the halo 165 is cooler than the workpiece, it can collect deposits from the polymerizing gas chemistry at a faster rate, which can also affect the etch rate at the edge of the workpiece.

[0036] The second type of non-uniformity is referred to as a linear non-uniformity. As described above, the workpiece 10 is scanned in the Y direction through the ribbon ion beam. Often the beam current profile of the ribbon in the X direction is not constant. Rather, often the current profile near the edge of the ribbon ion beam can be lower or higher than the current profile near the center of the ribbon ion beam.

[0037] 3, the temperature of the halo 165 may be controlled by placement of a resistive heater 335 on the surface of or embedded within the halo 165. When placed on the surface, the resistive heater 335 may be located on the underside of the protective cover 166 facing the frame 168 such that it is not exposed to the ion beam 106.

[0038] In certain embodiments, the resistive heater 335 may include a pattern disposed on the surface of the halo 165. For example, the resistive heater 335 may be a nickel chrome (NiCr) pattern disposed on the underside of the protective cover 166. This pattern may then be coated with an insulating material, such as a polyimide spray coating or Kapton tape, to insulate it from the frame 168. Of course, the resistive heater may be implemented in other ways. In this embodiment, the pattern is disposed between the protective cover 166 and the frame 168. Furthermore, in certain embodiments, the resistive heater 335 may be disposed within the protective cover 166 or may be embedded within the protective cover 166.

[0039] In other embodiments, the resistive heater 335 may be disposed on the underside of the frame 168 and may be electrically insulated from the frame 168. In each of these embodiments, the resistive heater 335 may be disposed in a location that allows for heating of the halo 165 while not exposing the resistive heater 335 to the ion beam 106.

[0040] In certain embodiments, the ends of the resistive heaters 335 communicate with a power source that is part of the thermal controller 190, such as a DC or AC power source. For example, a 208 VAC power source capable of generating up to 10 A may be used for each resistive heater 335. Of course, other power sources may be used, such as a 120 VAC power source or a DC power source. In some embodiments, the resistive heaters 335 are located as close to the inner diameter as possible to affect the temperature of the halo 165 in the vicinity of the workpiece 10.

[0041] A temperature sensor 336, such as a thermocouple or thermistor, may also be located on the backside of the halo 165. The temperature sensor 336 may be in communication with the thermal controller 190. The thermal controller 190 adjusts the voltage and / or current supplied to the resistive heater 335 based on the temperature measured by the temperature sensor 336. In an alternative embodiment, open loop control may be employed such that the temperature sensor 336 is not used.

[0042] FIG. 3 shows two resistive heaters 335; one on the left creates a first thermal zone and the second on the right creates a second thermal zone. However, the disclosure is not limited to this embodiment. Additionally, while FIG. 3 shows the resistive heaters 335 as a serpentine pattern, other patterns may be used. The halo 165 may be divided into any number of thermal zones. In certain embodiments, the resistive heaters 335 may increase the temperature of the thermal zones by up to 100° C.

[0043] For example, as shown in Figure 4, the halo 165 may be divided into four zones 302, 303, 304, 305. Each thermal zone includes an independently controlled resistive heater 335. Optionally, each thermal zone may include a dedicated temperature sensor 336 to independently control the temperature of each thermal zone. By utilizing four thermal zones, both radial and linear non-uniformities can be addressed, as described below.

[0044] For example, the boundaries between the thermal zones in FIG. 4 are at 45°, 135°, 225°, and 315°. However, other sizes are possible. For example, the two thermal zones 302, 304 may be larger or smaller than the other two thermal zones 303, 305. For example, when the two thermal zones 302, 304 are larger than the other two thermal zones, the boundaries between the thermal zones may be at 60°, 120°, 240°, and 300°. Similarly, when the two thermal zones 302, 304 are smaller than the other two thermal zones, the boundaries between the thermal zones may be at 30°, 150°, 210°, and 330°.

[0045] In certain embodiments, these thermal zones 302-305 may be independently controlled. In other embodiments, two or more thermal zones may be commonly controlled. For example, the two thermal zones 303, 305 corresponding to the positions where the ends of the ribbon ion beam strike the workpiece may be commonly controlled. Similarly, the other two thermal zones 302, 304 may be commonly controlled.

[0046] 5A-5E show etch rate maps for five different combinations of etch species and workpiece type. These etch rate maps are generated by measuring the thickness of the workpiece at multiple locations before the etch operation and measuring the thickness at the same locations after the etch operation. Region 580 is etched to a greater extent than other regions. Region 582 is etched to a lesser extent than other regions. Region 581 is an area of ​​etch rate between these two extremes.

[0047] Note that each of these etch rate maps shows either radial non-uniformity, linear non-uniformity, or a superposition of the two types of non-uniformity. In particular, Figures 5A and 5C show that linear non-uniformity dominates. Figures 5B and 5D show that radial non-uniformity dominates. Figure 5E shows both types of non-uniformity. In particular, in Figure 5E, the radial non-uniformity causes the outer edge of the workpiece to be etched more than the center. Additionally, the linear non-uniformity causes the ends of the ribbon ion beam to be etched less than the center of the ion beam. When these two non-uniformities are combined, only the top and bottom edges of the workpiece are etched more than the rest of the workpiece.

[0048] 6A-6E show temperature profiles that may be used to compensate the etch rate maps corresponding to FIGS. 5A-5E, respectively. Note that in FIGS. 5A and 5C, the etch rate along the left and right edges is less than elsewhere on the workpiece. Thus, in this situation, the thermal zones 303, 305 are set to a different temperature than the other thermal zones, as shown in FIGS. 6A and 6C. For many workpieces and etch species, the etch rate is directly proportional to temperature. Thus, to increase the etch rate along the left and right edges of the workpiece, the thermal zones 303, 305 are set to a higher temperature than the other thermal zones. Of course, for some etch chemistries, the etch rate may be inversely proportional to temperature. In this case, to increase the etch rate along the left and right edges of the workpiece, the thermal zones 303, 305 are set to a lower temperature than the other thermal zones.

[0049] Figures 5B and 5D show radial non-uniformity where the outer edge has a lower etch rate than the rest of the workpiece. In these cases, as shown in Figures 6B and 6D, all of the thermal zones 302-305 are maintained at a different temperature. If the etch rate is directly proportional to temperature, the thermal zones 302-305 are set at a higher temperature than the workpiece. If the etch rate is inversely proportional to temperature, the thermal zones 302-305 are set at a lower temperature than the workpiece.

[0050] Figure 5E shows an example where the top and bottom edges of the workpiece have a higher etch rate than the rest of the workpiece. Thus, as shown in Figure 6E, if the etch rate is directly proportional to temperature, the thermal zones 302, 304 are set at a lower temperature than the rest of the thermal zones. If the etch rate is inversely proportional to temperature, the thermal zones 302-304 are set at a higher temperature than the rest of the thermal zones.

[0051] Thus, the halo 165 of FIG. 4 can be used to compensate for both radial and linear non-uniformities.

[0052] Thus, in one embodiment, controller 180 receives information about the etching species being used, as well as the type of workpiece. This information may be entered via an input device such as a keyboard or touch screen. Based on this information, controller 180 commands thermal controller 190 the desired temperature for each of the thermal zones in halo 165. Thermal controller 190 then provides power to each thermal zone to achieve the desired temperature profile.

[0053] The thermal controller 190 may be implemented in a number of ways. In one embodiment, each thermal zone in the workpiece holder has a corresponding dedicated power supply. In other embodiments, a particular thermal zone may always be set to the same temperature. In these embodiments, a single power supply may be used to power more than one thermal zone.

[0054] In another embodiment, the thermal controller 190 may have one power supply for each power level, with the outputs of these power supplies used as inputs to multiple switches or multiplexers, with each switch then being used to select which output is applied to each thermal zone.

[0055] Additionally, halo 165 is also in communication with halo bias power supply 175 so that the etch pattern can be modified by manipulating the voltage applied to halo 165. For example, as discussed above, the etch rate patterns of Figures 5B and 5D exhibit radial non-uniformity, which may be corrected by applying a different voltage to halo 165 than the voltage applied to workpiece holder 155.

[0056] In these embodiments, the controller 180 receives information about the etch species being used, as well as the type of workpiece. This information may be entered via an input device such as a keyboard or touch screen. Based on this information, the controller 180 commands the halo bias power supply 175 the voltage to be applied to achieve the desired change in edge etch rate.

[0057] Finally, in certain embodiments, it may be possible to use both voltage and temperature manipulation of the halo to address non-uniformities. For example, controller 180 may vary the voltage applied to halo 165 to compensate for radial non-uniformities, while controller 180 may use different thermal zones to compensate for linear non-uniformities.

[0058] The embodiments described above in this application may have many advantages: As mentioned above, certain processes utilize very tight tolerances on the etch rate across the workpiece, such as a 3 sigma value of 3% or less.

[0059] By manipulating the voltage of the halo 165, the etch rate along the edge of the workpiece can be varied. For example, in one test, a voltage of 100V was output by the halo bias power supply 175. The etch rate along the edge of the workpiece changed by only 2% compared to an etching process in which the halo was maintained at the same voltage as the workpiece holder 155. A higher output voltage from the halo bias power supply 175 can result in a greater change in the etch rate along the edge of the workpiece.

[0060] Similarly, by manipulating the temperature of various regions of the workpiece, the etch rate associated with each region can be varied to achieve more uniform results across the workpiece.

[0061] The present disclosure is not limited in scope by the specific embodiments described herein. Various embodiments of the present disclosure and modifications of the present disclosure other than those described above will be apparent to those skilled in the art from the above description and the accompanying drawings, as well as those described herein. Thus, such other embodiments and modifications are intended to be included within the scope of the present disclosure. Furthermore, although the present disclosure has been described herein in the context of specific implementations in specific environments for specific purposes, those skilled in the art will recognize that its usefulness is not limited thereto, and the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Therefore, the claims set forth below should be construed in the broadest possible light in accordance with the scope and spirit of the present disclosure as described herein.

Claims

1. a semiconductor processing system for generating a ribbon ion beam; Workpiece holder, a halo disposed around the workpiece holder; and 1. An etching system comprising: a scan motor for moving the workpiece holder through the ribbon ion beam, the halo comprises a plurality of resistive heaters for modifying a temperature of the halo; and the halo comprises a conductive frame having an opening for receiving the workpiece holder, and a protective cover disposed on the conductive frame. Etching system.

2. The etching system of claim 1, wherein the multiple resistive heaters are positioned within or on the protective cover.

3. The etching system of claim 2 , wherein the plurality of resistive heaters are disposed on an exterior surface of the protective cover facing the conductive frame.

4. 10. The etching system of claim 1, further comprising a temperature sensor disposed on said halo for monitoring a temperature of said halo.

5. The etching system of claim 1, further comprising a halo bias power supply for biasing the conductive frame at a voltage different from a voltage applied to the workpiece holder.

6. 6. The etching system of claim 5, wherein the halo bias power supply is referenced to the workpiece holder such that the halo maintains a constant voltage offset from the workpiece holder.

7. The etching system of claim 5 , wherein the halo is electrically isolated from the workpiece holder using an insulating material.

8. a semiconductor processing system for generating a ribbon ion beam; Workpiece holder, a halo disposed around the workpiece holder; and 1. An etching system comprising: a scan motor for moving the workpiece holder through the ribbon ion beam, the halo includes multiple thermal zones to compensate for both radial and linear etch rate non-uniformities; and the halo comprises a conductive frame having an opening for receiving the workpiece holder, and a protective cover disposed on the conductive frame. Etching system.

9. The etching system of claim 8, wherein a plurality of resistive heaters are disposed within or on the protective cover.

10. 10. The etching system of claim 9, wherein the plurality of resistive heaters are disposed on an exterior surface of the protective cover facing the frame.

11. 10. The etching system of claim 8, wherein the halo is divided into a plurality of thermal zones.

12. 12. The etching system of claim 11, wherein the multiple thermal zones can be independently controlled.

13. 12. The etching system of claim 11, further comprising a thermal controller, the thermal controller comprising a plurality of power sources in communication with the plurality of thermal zones, and a controller in communication with the thermal controller, wherein a workpiece type and an etch species are input into the controller, and the thermal controller provides power to the plurality of thermal zones to achieve a desired temperature profile.

14. 14. The etching system of claim 13, further comprising a temperature sensor disposed within the at least one thermal zone for monitoring a temperature of the at least one thermal zone.

15. a semiconductor processing system for generating a ribbon ion beam; Workpiece holder, a halo disposed around the workpiece holder, the halo comprising a conductive frame having an opening for receiving the workpiece holder and a protective cover disposed on the conductive frame; a scan motor for moving the workpiece holder through the ribbon ion beam; and An etching system comprising a halo bias power supply for biasing the conductive frame at a voltage different from a voltage applied to the workpiece holder.

16. 16. The etching system of claim 15, wherein the halo bias power supply is referenced to the workpiece holder such that the halo maintains a constant voltage offset from the workpiece holder.

17. 16. The etching system of claim 15, wherein the halo is electrically isolated from the workpiece holder using an insulating material.

18. 16. The etching system of claim 15, wherein the conductive frame is divided into a plurality of conductive regions and a voltage applied to each conductive region is independently controlled to compensate for both radial and linear etch rate non-uniformities.

19. 16. The etching system of claim 15, further comprising a controller in communication with said halo bias power supply, wherein a workpiece type and an etch species are input into said controller and said halo bias power supply provides power to said conductive frame to achieve a desired change in edge etch rate.

20. The etching system of claim 1, wherein the temperature of the halo is adjusted to compensate for both radial and linear etch rate non-uniformities.

21. An etching system as described in any one of claims 1, 8, or 15, wherein the protective cover comprises a dielectric material or a silicon substrate.

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