Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/02—Details
  • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
  • H01J37/147—Arrangements for directing or deflecting the discharge along a desired path
  • H01J37/1472—Deflecting along given lines
  • H01J37/1474—Scanning means
  • H01J37/1475—Scanning means magnetic
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/02—Details
  • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
  • H01J37/153—Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
  • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
  • H01J37/3171—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation for ion implantation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/05—Arrangements for energy or mass analysis
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/15—Means for deflecting or directing discharge
  • H01J2237/152—Magnetic means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/153—Correcting image defects, e.g. stigmators
  • H01J2237/1536—Image distortions due to scanning
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/30—Electron or ion beam tubes for processing objects
  • H01J2237/317—Processing objects on a microscale
  • H01J2237/31701—Ion implantation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/30—Electron or ion beam tubes for processing objects
  • H01J2237/317—Processing objects on a microscale
  • H01J2237/31701—Ion implantation
  • H01J2237/31703—Dosimetry
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/30—Electron or ion beam tubes for processing objects
  • H01J2237/317—Processing objects on a microscale
  • H01J2237/31701—Ion implantation
  • H01J2237/31706—Ion implantation characterised by the area treated
  • H01J2237/31708—Ion implantation characterised by the area treated unpatterned

Definitions

• the present invention relates generally to ion implantation systems, and more specifically to improved systems and methods for providing a
• loft implanters are conventionally utilized to place s specified quantity of dopants or impurities within semiconductor workpieces or wafers, in a typical ion implantation system, a dopant material is ionized, therein genefatihg a beam of ions.
• the jort beam is directed at a surface of the semiconductor wafer to implant ions into the wafer, wherein the tons penetrate the surface of the wafer and form regions of desired conductivity therein.
• ion impfcantation has particular Use in tine fabrication of transistors in semiconductor workpieces.
• Atypical ton impianter comprises an ion source for generating the Ion beam, a beamline assembly having a mass analysis apparatus for directing and/or filtering (e.g., mass resolving) ions within the beam, and a target chamber containing one or more wafers or workpieces to be treated.
• a mass analysis apparatus for directing and/or filtering (e.g., mass resolving) ions within the beam
• a target chamber containing one or more wafers or workpieces to be treated.
• ion implanters allow respectively varied dosages and energies of ions to be implanted, based bn the desired characteristics to be achieved within the workpiece, For example, high-current ion implanters are typically used for high dose implants at low to medium energies, and medium- current to low-current ion implanters are utilized for lower dose applications, typically at higher energies.
• implants at energies down to 300 electron Volte are desirable, while concurrently minimizing energy contamination, maintaining tight control of angle variation within the ion beam as well as across the workpiece, and also while providing high workpiece processing throughput.
• Hybrid scanned beams can provide very good dose uniformity at high throughput, whereby the ion beam is electrically or magnetically scanned relative to the workpiece, and whereby the workpiece is mechanically translated through the scanned ion beam.
• the ion beam is electrically or magnetically scanned relative to the workpiece, and whereby the workpiece is mechanically translated through the scanned ion beam.
• foe throughput of workpieces through the system is limited by the size of the ion beam and the large scan amplitudes utilized to provide full over-scan Of the workpiece by the ion beam.
• the present disclosure provides a system and a method by which an efficiency of an ion implantation system is increased beyond conventional systems, wherein an improved design of one or more of a scan magnet and corrector magnet are advantageously provided.
• the following presents a simplified summary of the invention in order to provide a basic understanding of some aspects Of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical: elements of the Invention nor to delineate the scope of the invention. Rather, the purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
• the present disclosure provides a system and method for providing a non- uniform flux profile of a scanned ion beam.
• an ion implantation system wherein an ion beam is configured to be scanned at an ion beam scan frequency across a surface of a workpiece, therein defining a scanned ion beam (also called a “scanned ribbon”).
• a spot ion beam is formed and provided to a scanner, and a scan waveform having a time-varying potential is applied to the scanner.
• the ion beam is scanned by the scanner across a scan path, generally defining a scanned ion beam comprised of a plurality of beamlets.
• the scanned beam is then passed through a corrector apparatus.
• the corrector apparatus Is configured to direct the scanned ion beam toward a workpiece at a generally constant angle of incidence across the workpiece.
• the corrector apparatus further comprises a plurality of magnetic poles configured to provide a non- uniform flux profile of the scanned ion beam at the workpiece.
• Fig. 1A is one embodiment of an ion implantation system with a scanner, corrector, and dosimetry system in accordance with various aspects of the present disclosure.
• Fig, 1 B js one embodiment of the scanner of Fig, 1 A and several scanned ion beams.
• Fig, 1C is one embodiment of a triangular scanning current waveform in the scanner of Figs. 1A and 1B.
• Fig. 1D is a perspective view illustrating one scanned ion beam striking a workpiece in the system of Figs. 1A at several discrete points in time.
• Fig. 2 is a perspective view ofthe magnetic poles and beamguide of a conventional corrector apparatus.
• Fig. 3A is a schematic representation of an ideal ion beam passing through an ideal scanner and corrector apparatus.
• Fig, 3B is a graph illustrating an ideal beam flux profile using file idea! scanner and corrector apparatus of Fig. 3A.
• Fig. 30 is a graph illustrating ah exemplary flux profile produced using a triangle wave current waveform that is not uniform.
• Fig. 4 is perspective view of the magnetic poles and beamguide of a corrector apparatus in accordance with various aspects ofthe present disclosure.
• Fig. 5A is a schematic representation of an ion beam passing through a scanner and corrector apparatus in accordance with various aspects ofthe present disclosure
• Fig. 5B is graph illustrating a non-uniform beam flux profile using the scanner and corrector apparatus of Fig. 5A,
• Fig. 6A is a schematic representation of a scanned ion beam passing through another scanner and another corrector apparatus in accordance with various aspects of the present disclosure.
• Fig. 6B is graph illustrating a non-uniform beam flux profile using the scanner and corrector apparatus of Fig. 6A.
• Fig. 7 is a chart illustrating first and second functions relating scan angle tp scan current applied to a scanner in accordance with various aspects of the present disclosure.
• Fig, 8 is a chart illustrating various pole designs in accordance with various aspects of the present disclosure.
• Fig, 9 is a flow diagram illustrating a method for providing a non-uniform flux profile to a workpiece in accordance with various aspects of the present disclosure.
• DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described with reference to the drawings wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures are not necessarily drawn to scale.
• Fig. 1A illustrates an exemplary ion implantation system 10 comprising a terminal 12, a beamline assembly 14, and an end station 16, wherein the ion implantation system is configured to implant ions into a workpiece 18 positioned in the end station.
• the terminal 12 for example, comprises an ion source 20 powered by a high voltage power supply 22, wherein the ion source produces and directs an ion beam 24 to the beamline assembly 14.
• ions produced in the ion source 20 are extracted and formed into the ion beam 24, whereby the ion beam is directed along a beam path 26 within the beamline assembly 14 toward the end station 18.
• the beamline assembly 14 for example, comprises a beamgulde 28 and a mass analyzer 30, a resolving aperture 34, a scanning system 36, and a corrector apparatus 38 " , A dipole magnetic field is established within the mass analyzer 30 to pass only ions of appropriate chargeTo-mass ratio through the resolving aperture 34.
• the scanning system 36 for example, may comprise an electrostatic or magnetic scanning system.
• the scanning system 38 illustrated In the exemplary embodiment of Fig 1A shows a magnetic scanner 40 having a power supply 42 coupled to scanner coils 44. The scanner 40 is positioned along the beam path 26 and receives the ion beam 24 after being mass analyzed by the mass analyzer 30, wherein the scanner of Fig.
• A magnetically scans the ion beam to generally define a scanned ion beam 46 (e g., also referred to as a “scanned ribbon").
• the corrector apparatus 38 directs the scanned ion beam 46 to the end station 16 such that the scanned ion beam strikes the workpiece 18 at a generally constant angle of incidence across the workpiece.
• the scanning of the ion beam 24 to form the scanned Ion beam 46 is controiled by a controi system 48, such that the control system generally controls the power supplied to the scanner coils 44, thus magnetically scanning the Ion beam across the workpiece 18,
• the ion implantation system 10 may further comprise various beam forming and shaping structures (not shown) extending between the ion source 20 and foe end station 16, wherein the forming and shaping structures maintain and bound the ion beam 24 as it is transported to the workpiece 18 in the end station 16.
• This passageway through which the ion beam 24 is maintained is typically kept at vacuum to reduce the probability of iohs being deflected from the beam path 26 vie collisions with air molecules.
• the ion implantation system 10 may employ different types of end stations 16.
• "batch" type end stations can simultaneously support multiple workpieces 18, such as on a rotating support structure, Wherein the workpieces are rotated through the path of the ion beam until all the workpieces are completely implanted.
• a "serial” type end station supports a single workpiece 18 along the beam path for implantation, wherein multiple workpieces are implanted one at a time In serial fashion, with each workpiece being completely implanted before implantation of the next workpiece begins.
• the illustrated end station 16 is a "serial" type end station that supports a single workpiece 18 along the beam path for implantation (e.g., a semiconductor wafer, display panel, or other workpiece to be implanted with Ions from foe beam 24), wherein a dosimetry system 50 is situated near the workpiece location for calibration measurements prior to implantation operations. During calibration, the ion beam 24 passes through the dosimetry system 50.
• implantation e.g., a semiconductor wafer, display panel, or other workpiece to be implanted with Ions from foe beam 24
• a dosimetry system 50 is situated near the workpiece location for calibration measurements prior to implantation operations.
• the ion beam 24 passes through the dosimetry system 50.
• the dosimetry system 50 for example, comprises one or more profilers 52 that are configured to traverse a profiler path 54, thereby measuring the profile of the ion beam 24 (e g., the scanned ion beam 46),
• the corrector apparatus 38 directs the scanned ion beam 46 to the ehd station 16 such that the scanned beam strikes one or more profilers 52 of the dosimetry System 50 at a generally constant angle of incidence.
• the profiler path 54 for example, is positioned along an implantation plane associated with a surface 56 of the workpiece 18.
• the one or more profilers 52 comprise a current density sensor 58 (e.g., a Faraday cup) for measuring the current density of the scanned ion beam 46:
• the current density sensor 58 moves in a generally orthogonal fashion relative to the scanned ion beam 46 and thus traverses the width of the scan path.
• the dosimetry system 50 is further operably coupled to the control system 48 to receive command signals therefrom and to provide measurement values thereto to implement the measurement aspects of the calibration method of the disclosure as described further herein.
• the scanner 36 receives the ton beam 24, and a Current waveform applied by the power supply 42 to the scanner coils 44 operates to scan the ion beam 24 back and forth in the X direction (e,g., the scan direction) to spread the ion beam out into an elongated "scanned ribbon" beam (e.g., the scanned ion beam 46), having an effective X direction width that may be at feast as wide as or wider than the workptece(s) 18 of interest
• the Scanned ton beam 46 is then passed through the corrector apparatus 38 that directs the beam toward the end station 16 generally parallel to the Z direction (e,g., generally perpendicular to foe surface 56 of the workpiece 18).
• a power supply or supplies is connected to multiple electrodes spaced around the beam.
• the electric field between the electrodes is farther adjusted to scan the ton beam.
• all different types of scanning systems 36 are considered, and the magnetic system of Fig. 1A is one illustrative example of such a scanning system.
• FIG. 1B An exemptary magnetic version of the scanning system 36 is further illustrated to Fig, 1B, wherein the power supply 42 provides alternating currants to the coils 44, as illustrated in a waveform 60 in Rg. 1C.
• the time*varytog waveform 60 a triangular waveform) creates a time varying magnetic field across the beam path 26 therebetween, by which the ion beam 24 is bent or deflected (e.g., scanned) along a scan direction (e.g , the X direction in Figs. 1A, 1B, and 2B-2F),
• the positively charged ions of the ion beam 24 are subjected to a lateral force in the negative X.
• the current / is zero, such its at time “d” In Fig, 1C, the beam 24 passes through the scanner 40 unmodified.
• the positively charged ions of the ion beam 24 are subjected to a lateral force in the positive X direction:
• Fig, 1B shows the resulting deflection associated with the scanned beam 46 as the ioft beam 24 passes through the scanner 40 at several discrete points in time during scanning prior to entering the cortector apparatus 38 of Fig, 1A.
• the scanned and parallelized ion beam 24a in Fig. ID corresponds to the applied electrode voltages or currents at the time "a" in Fig. 1C, and subsequently, the ion beam 24b-24g is illustrated in Fig, 10 for scan voltages or currents at corresponding times“b ⁇ “g * of Fig, 1C for a single generally horizontal scan across the workpiece 18 in the X direction.
• a translation apparatus 62 e g,, a mechanical actuation apparatus
• a translation apparatus 62 translates the workpiece 18 in the Y-direction fag., slow scan direction) concurrent with scanning Of the ion beam 24 back and forth in the X-direction (e. ., fast scan direction) via the scanner 40, whereby the ten beam 24 is Imparted on the surface 56 of the workpiece 18.
• a triangle wave in voltage or current applied to the scanner 40 produces a triangle wave in beam angle, and after the corrector apparatus 38, a uniform scanned ribbon beam 46(e. ,, ⁇ uniform flux profile).
• a uniform scanned ribbon beam 46 e. , ⁇ uniform flux profile
• the current waveform from the power supply 42 to the scanner 40 can be modified fo produce a desired dose profile GOT the workpiece 18. While in some instances, the dose profile is desired to be uniform, other non- uniform profiles are also sometimes desirable.
• the specific current waveform that produces a desired flux profile generally depends on how the beam current and shape of the ion beam 24 change as the ion beam is scanned across the workpiece 18, An ion beam 24 haying a minimal size may have little to no change in shape across the scan, thereby producing waveforms with a minimum amplitude and minimal modifications or deviations from the nominal triangle wave. Such a rriinimally ⁇ sized ion beam 24, for example, is thus most efficient and least demanding on the scanner 40.
• magnetic scanners and corrector apparatuses are utilized in high-eutrent beam tines, as opposed to electrostatic scanners and corrector apparatuses which aro used in lower-current beam lines, such as those used in medium-current implanters.
• S-bend magnets can be utilized in the corrector apparatus 38, whereby path lengths of the ion beam are more similar across the scan, as compared to the utilization of a single-bend magnet or electrostatic parallelizing lens in the corrector apparatus.
• Fig. 2 illustrates a conventional configuration Of poles 7QA, 70B associated with a respective entrance 72 and exit 74 of a conventional corrector apparatus 75.
• Fig. 2 does not show the yoke and coils of the magnet or magnets because these are not generally as important to defining the beam trajectories*
• Fig, 3A further illustrates the conventional corrector apparatus 75 that could be positioned downstream of the scanner 40, whereby the paths 26 of the various trajectories of the ion beams 24a-24g are at different scan angles Q» - q b as they exit the scanner, wherein the scan angles
• a “ideal” ion beam e,gr., appoint" ion beam
• a triangle wave as shown in Fig. 1C
• a generally uniform flux profile 76 across the workpiece 18 is produced, as illustrated in Fig. 3B
• the generally uniform flux profile 76 of Fig. SB for example, has an average flux Yo that results from substantially uniform scanning and conventional corrector apparatus 75.
• a "real" ion beam changes shape, size, and current as the beam is scanned, and a real flux profile 77 produced with a hiangle wave current waveform is not uniform, as illustrated in Fig. 3C.
• Increased throughput of workpieces 18 through the system 10 can be attained, at least partially, by configuring the scanner 40 and/br corrector apparatus 38 to produce a non- uniform flux profile across the workpiece 18 when using foe nominal triangle waveform 60 of Fig. 1C and an ideal point beam, while stiil maintaining
• Fig. 5 illustrates one such example of the corrector apparatus 38 in accordance with various aspects of the present disclosure, wherein poles 8QA, 80B of the corrector apparatus are configured to provide a non-uniform flux profile of the ion beam 24 as it passes through an entrance 82 and exit 84, thereof.
• Various shapes of the poles 80A, BOB of the corrector apparatus 38, associated With the scanner 40 of Fig, 5A, for example, can advantageously provide a non-uniform flux profile 86, as illustrated in Fig. 5B, whereby a larger amount of beam flux is provided proximate to the edges 78 of the workpiece 18 than proximate a center 89, thereof, it should be noted that the present disclosure may be applied to any corrector apparatus 38, whether the corrector apparatus comprises a single magnet, or multiple magnets in an S-bend configuration, Further, it should be noted that the scanner 40 and any magnet associated therewith may be bipolar (as shown), dr unipolar, such that the ion beam 24 is always bent.
• the beam flux provided to the workpiece 18 is inversely proportional to the spacing of the trajectories of the beams 24ar24g. That is, the uniform spacing over time provided by the scanner 40 between beams 24a - 24b, 24b-24C j 24c- 24d, etc, produces a uniform fiux out of the scanner 40.
• the various scan angles are whole number multiples of any given scan
• the varying densities between beams 24a - 24b, 24b-24c, 24c-24d, etc. produce a varying flux for said Uniform scanning of the beam, with more flux at the edges 78 of the workpiece 18 where foe beams are closer to one another, and less dense in the center 88 where they are further apart.
• the non-*iniiorm flux profile 86 of Fig, 5B is achieved, while providing uniform flux profile cut of the scanner, and thus providing the similar average flux Yo to that resulting from foe uniform scanning of Fig. 4B.
• a modified scanner 90 may be configured such that the magnets of the scanner provide a non-linear relationship between drive current and scan angle in conjunction with the conventional corrector magnet 68.
• the modified scanner 90 may be configured to provide a flux profile 92 of Fig, 6B that is generally equivalent to the flux profile 86 Of Fig. 58, assuming an ideal point beam and a triangle current waveform.
• poles of the scanner of the present disclosure may be shaped to have a predetermined profile such that a uniform change in current provides a non-uniform change in scan angle.
• the flux profile 92 of Fig. 68 may be achieved utilizing the same input to the Scanner 40, while attaining greater flux at the edges 78 to
• the spanner 40 of Fig. 5A would hold the ion beam 24 proximate to the edge® 78 for longer times than the remaining portion of the workpiece 18 to attain the desired flux at the edges, whereby an AO waveform to the scanner may be highly modified and potentially be bandwidth limited.
• the present disclosure provides a solution to such a complex and deleterious AC spanning waveform, whereby the scanner and corrector systems advantageously provides a greater amount of flux to the edges 78 of the workpiece.
• the flux at the edge(s) 78 of the workpiece 18 may be between 10% and 100% greater than the flux at the center 88 of the workpiece.
• the flux profile 86, 92 of Figs. 5B and 6B may be generally parabolic with an unmodified scan waveform applied to toe scanner 40.
• the flux profile 86, 92 with an unmodified scan waveform is generally uniform over a central region associated With the center 88 of the workpiece 18 of Figs.
• the varying densities between beams 24a-24b, 24b-24c, 24c- 24d, etc. produce varying flux for non-uniform scanning of the beam via the modified scanner 90, thus producing more flux at the edges 78 of the workpiece 18 where the beams are closer to one another, and less dense in the center 88 where they are further apart.
• the various scan angles $ may differ for any given scan time t
• the modified scanner 90 is
• trajectories of beams 24a ⁇ 24g provide a similar flux profile 92 of Fig. 6B as foe flux profile 86 of Fig. 5B.
• Fig. 7 illustrates first and second functions wi and wz relating scan angle Q to scan current I applied to the scanner with a real beam after uniformity correction has modified the scan waveform to provide uniform flux.
• the first function wi provides a uniform flux profile (eg., similar to the uniform flux profile 76 in Fig. 3B) after uniformity correction when used with the conventional scanner and corrector system of Fig. 3A, where the slope is smelter at extremes 94 of the scan angles Q and larger in the middle 96 of Fig. 7.
• the second function, w3 ⁇ 4 is the function after uniformity correction for the disclosed, improved systems Where foe scan angle Q is a more linear function of scan current I.
• the non-uniform flux profiles 86» 92 of Figs. 5B and 6B can be achieved via a combination of the corrector apparatus 38 of Fig. 5A and the modified scanner 90 of Fig. 6A,
• various designs of foe physical magnets and poles 60A, 80B associated with either of foe corrector apparatus 38 of Fig. 5 and/or modified scanner 90 of Fig. 6A are contemplated, whereby modified optics and techniques can be utilized in designing various pole shapes.
• Fig. 8 illustrates a first pote edge 100 and second pole edge 102 configured to provide a particular desired flux profile.
• the first and second pole edges 100, 102 may be associated with foe conventional corrector 68 of Fig. 6A (e,g though a standard S-bend magnet), while modified pole edges 104, 106, 108, 110 of Fig. 8 may be associated with the corrector apparatus 38 of Fig. 5A, whereby the non-uniform flux profiles 86, 92 of Figs ⁇ SB and 6B are generally defined by the beam 24, respectively.
• the modified pole edges 104, 106, 108, 110 of Fig. 8 may be accordingly configured to achieve various desired optical properties of the magnet For example, pole rotations, pole edge curvature, pole face curvature, etc. may be utilized in the configuration of the modified pole edges104, 106, 108, 110.
• Fig. 9 illustrates an exemplary method 3 ⁇ 4C!0 for controlling the flux profile Of a scanned ribbon Nam (e.g perhaps a scanned spot Nam),
• a spot ton beam is provided to a scanner, and in act 204, a scan waveform having a time-varying potential is applied to tN scanner.
• the scan waveform for example, may comprise a triangle wave.
• the spot ion beam is scanned across a scan path, therein generally defining a scanned ion beam comprised of a plurality of beamlets.
• the scanned ion Nam is passed through a corrector apparatus, wherein the corrector apparatus is configured to direct the scanned ion beam toward a workpiece at a generally constant angle of incidence across the workpiece, in act 210, a plurality of magnetic poles of the scanner and corrector apparatuses provide a non-uniform flux profile of the scanned ion beam at the workpiece with an ideal point beam scanned fully over the workpiece.
• the present disclosure thus provides a non-uhtdrm flux profile prior to uniformity correction in an ideal case.
• the present disclosure contemplates one or more of the scanner and corrector apparatus being configured such that, with the ideal case of a point beam scanned My over the workpiece at substantially constant scan speed, the flux substantially
• the flux profile is substantially uniform or has a predetermined non-uniformity.
• Conventionally » the edges of the workpiece experience decreased current for various reasons discussed above, thus providing a generally parabolic flux profile having decreased flux near the edges of the workpiece.
• uniformity correction routines have been conventionally performed to hold the ion beam at the edges for extended times in order increase the flux and provide greater uniformity as shown in Fig. 7.
• the present disclosure advantageously utilizes foe scanner and corrector apparatuses to increase beam flux at the edges of the workpiece, such that when such lower current is present at the edge, the net flux profile is flatter, and the scan system and uniformity correction can be configured to hold foe ton beam for a shorter duration at the edge, thus wasting less beam current.
• the present disclosure contemplates providing various magnetic fields to a corrector apparatus and/or a scanner, whereby foe pole shaping, pole face rotations, and curvatures associated with respective magnets provide the desired non-uniform flux profile described herein.
• a face of the magnetic pole may be varied to effectively change foe path length through the magnetic field for each beamlet across the ribbon beam. Varying the path length through the magnetic field thus varies the degree to which the beamiet bends, and can thus be similarly varied to exit the corrector apparatus in a parallel manner.
• beamiets associated with edges of the workpiece are closer together than in the middle of the workpiece, thus providing more flux at the edges of the workpiece man in the middle.

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