EP1145278A1 - Cathode a configuration variable des aimants - Google Patents

Cathode a configuration variable des aimants

Info

Publication number
EP1145278A1
EP1145278A1 EP98964215A EP98964215A EP1145278A1 EP 1145278 A1 EP1145278 A1 EP 1145278A1 EP 98964215 A EP98964215 A EP 98964215A EP 98964215 A EP98964215 A EP 98964215A EP 1145278 A1 EP1145278 A1 EP 1145278A1
Authority
EP
European Patent Office
Prior art keywords
target
sputtering
plasma
shape
magnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98964215A
Other languages
German (de)
English (en)
Inventor
Steven Hurwitt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tokyo Electron Ltd
Original Assignee
Tokyo Electron Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tokyo Electron Ltd filed Critical Tokyo Electron Ltd
Publication of EP1145278A1 publication Critical patent/EP1145278A1/fr
Withdrawn legal-status Critical Current

Links

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
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
    • H01J37/3411—Constructional aspects of the reactor
    • H01J37/345—Magnet arrangements in particular for cathodic sputtering apparatus
    • H01J37/3455—Movable magnets
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • 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
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
    • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
    • H01J37/3405—Magnetron sputtering
    • H01J37/3408—Planar magnetron sputtering

Definitions

  • the present invention relates to a cathode used in a sputtering process, and more particularly, to a sputtering cathode assembly with a variable magnetic configuration that compensates for variations in deposition film thickness caused by erosion of a sputtering target.
  • sputtering cathode assemblies are commonly used to deposit metal or other conductive material as a thin film onto a surface of a substrate such as a semiconductor wafer.
  • Sputtering cathode assemblies include a vacuum chamber in which a sputtering target is positioned in close proximity to the substrate. As energy is applied to the target, atoms are ultimately sputtered or dislodged from the surface of the target and deposited on substrate.
  • non-uniformities in a film are a result of there being more of a target structure (i.e. a sputtering source) located near a center of a substrate than at an outer edge of the substrate.
  • a target structure i.e. a sputtering source
  • an infinitely large target with a uniform erosion profile would be capable of overcorning film non-uniformity due to the target size. Therefore, it is desirable to make the target large with respect to the surface of the substrate being coated.
  • the size of the sputtering target which may be used. Usually, a compromise is made by providing a target having a diameter that is approximately one-half larger than that of the substrate being coated.
  • Designs for cathode assemblies have been optimized to shape the erosion profiles of the targets to compensate for the thinner edge coating effect and other factors contributing to non- uniformity of the film. This is frequently achieved by selectively configuring the magnet assemblies used to shape the plasma. For example, in order to compensate for tiiinness of a film at the substrate edge, magnet assemblies are often designed to produce a greater duration of plasma around the target edge. This causes the target to erode at a higher rate near the target edge to compensate for reduced target exposure near the substrate edge.
  • a magnet carrier plate 20 is arranged to be rotatable around center axis 26 on shaft 18.
  • the plate 20 includes an array of magnetic material 28 having a fixed predete ⁇ nined shape.
  • the magnetic material 28 is selectively configured so that there are portions positioned at various radii from the center axis 26 in an irregular partially-formed loop.
  • magnetic material 28 is oriented such that a north magnetic pole is at an outer perimeter face 32 while a south magnetic pole is at inner perimeter face 34.
  • the shape of the sputtering plasma and the resultant erosion of first target 72 adjacent magnetic material 28 is defined by a magnetic flux path 76 extending between the north 32 and south 34 magnetic poles which create a closed loop magnetic field tunnel on the face of the first target 72.
  • the profile 74 includes a substantially circular "bulls eye" pattern wherein the deeper and shallower portions of profile 74 are formed by the particular pattern shape of magnetic material 28.
  • a first outermost portion 78 of profile 74 is dominated by a rotational dwell of outermost areas 79 of the magnetic material 28, while the depth of erosion of a central portion 82 of the first target 72 is dominated by center areas 84 of magnetic material 28.
  • an erosion of an intermediate portion 86 between the first outermost portion 78 and the center portion 82 results from a rotational dwell of intermediate areas 88 of magnetic material 28.
  • the shape of the profile 74 in addition to other factors such as the size of the first target 72 and substrate 92 and the spacing between first target 72 and substrate 92 are some factors which determine film thickness uniformity. Further, thickness uniformity is not constant during the life of the target.
  • first target 72 is new, an initial sputtering surface 90 is substantially flat and at a known distance from the substrate 92 which is to be coated with sputtered material. As erosion progresses, the surface 90 gradually assumes the shape of profile 74. Together with the erosion, the distance between the surface 90 and substrate 92 increases.
  • Figure 3 illustrates sputtered material thickness across a diameter of a six-inch substrate.
  • Curve 94 illustrates sputtered material thickness obtained when first target 72 is new and surface 90 is substantially flat.
  • uniformity degrades as illustrated by curve 96 at the mid-point of target life.
  • first target 72 approaches the end of life, the thickness of sputtered material degrades to that illustrated by curve 98.
  • the progression of sputtered material thickness as first target 72 erodes, indicates a reduction of film thickness towards the edge of substrate 92.
  • sputtering targets of different materials or crystal structures perform differently in the sputtering process.
  • FIG 4A an angular distribution of material 120 sputtered from a location 122 on a second target 124 fabricated from aluminum is illustrated. This distribution shows that a majority of material sputtered is located predominantly normal to the target surface.
  • Figure 4B an angular distribution of material 132 sputtered from a location 126 on a third target 128 fabricated from terbium or gold is shown.
  • the sputtered material is distributed at lower angles along lobes 130 than that shown in Figure 4A. Optimizing the deposition uniformity for these and other materials requires replacement of the magnet structure. However, as previously described, this requires undesirable shutdown of the sputtering system.
  • a sputtering system for depositing a thin film onto a substrate wherein the system includes an evacuatable chamber which includes the substrate.
  • the system includes a target positioned within the chamber, wherein the target includes a back surface and a sputtering surface.
  • the system includes plasma for eroding the target to provide material for forming the thin film wherein erosion of the target occurs in a predetermined erosion pattern and is controlled by a shape of the plasma.
  • a magnet arrangement is provided which provides a magnetic field on the target for controlling the shape of the plasma, wherein the magnet arrangement is positioned adjacent the back surface.
  • the system also includes a support for supporting the substrate opposite the sputtering surface and an adjustment arrangement for adjusting a dwell time of the magnetic field over predetermined portions of the target to change the shape of the plasma to thereby change the erosion pattern of the target.
  • Figure 1 depicts a conventional rotating magnet assembly.
  • Figure 2 illustrates a side view of a conventional rotating magnet assembly and a target erosion profile.
  • Figure 3 shown film uniformity at various stages of target life.
  • Figure 4A illustrates angular distribution of material sputtered from an aluminum target.
  • Figure 4B illustrates angular distribution of material sputtered from an aluminum target.
  • Figure 5 is a view of a sputtering system having a variable magnet cathode in accordance with the present invention.
  • Figure 6 is a partial view of the system along view line 6-6 of Figure 5 and which depicts magnetic segments.
  • Figure 7 is a partial view of the system along view line 7-7 of Figure 5 and which depicts a yoke in an innermost position relative to a center axis.
  • Figure 8 is a view of the system when the yoke reaches its outermost position relative to the center axis, thus positioning the magnetic segments in an outermost area.
  • Figure 9 illustrates an outward shift in accordance with the present invention of an outermost portion of the erosion profile shown in Figure 2.
  • Figure 10 illustrates a curve which shows improved film iiniformity due to outward positioning of the magnetic segments.
  • FIG. 5 a sputtering system 10 in accordance with the present invention is shown.
  • the system 10 includes a stationary cover 14 which is removably affixed to a bottom housing 16 to form a cavity 12.
  • the cavity 12 is evacuated by a pump 142 to a vacuum level suitable for sputtering.
  • a fourth target 144 is positioned within the cavity 12.
  • the fourth target 144 includes a sputtering surface 146 from which target material is removed and which is ultimately deposited on a substrate 148 to form a thin film.
  • the system 10 also includes a support 150 for holding the substrate 148 in a position generally opposite the sputtering surface 146.
  • a sputtering gas such as argon
  • the fourth target 144 is then negatively energized by a power supply 108 to cause an emission of electrons from the fourth target 144, thus forming a cathode element 154.
  • the support 150 and substrate 148 are connected to ground 156 to form an anode element 158. Projecting through stationary cover 14 is a shaft 18.
  • Plate 20 has a first surface 22 to which shaft 18 is attached and a second surface 24 to which magnetic material 28 is attached. Plate 20 rotates about the center axis 26 of shaft 18.
  • a portion of the magnetic material 28, which is not located in the outermost areas 79, is removed to form first 134 and second 136 ends which are separated by a gap 138.
  • a plurality of magnetic segments 36-50 are disposed in the gap 138 between the first 134 and second 136 ends.
  • the magnetic segments 36-50 are arranged in a shape which is similar to the shape of the portion of the magnetic material 28 which is removed. It is understood however, that the magnetic segments 36-50 may be arranged in other shapes as desired.
  • Each of the magnetic segments 38-48 is positioned such that each is substantially in contact with adjacent magnetic segments.
  • magnetic segments 36 and 50 are substantially in contact with the adjacent magnetic segment 38 and 48, respectively, on one side and in contact with the first 134 and second 136 ends, respectively, on the opposite side.
  • the magnetic segments 36 - 50 are of the same magnetic orientation as the magnetic material 28.
  • the magnetic material 28 may include any known magnetic material, including metal or electromagnets, sufficient to generate suitable magnetic field strength to enhance the sputtering process. Referring to Figure 7 in conjunction with Figure 5, a partial view of the system 10 along line 7-7 of Figure 5 is shown.
  • Each of the magnetic segments 36-50 has a perpendicularly extending pin 52 projecting through a corresponding one of a plurality of slots 54 in plate 20.
  • the slots 54 control movement of each of the pins 52 and thus the magnetic segments 36-50 in the direction of arrow 56.
  • the system 10 further includes a yoke 58 which is adapted to slide on plate 20 in the direction indicated by arrow 56.
  • Yoke 58 includes spaced apart and opposed upper 60 and lower 62 convex surfaces to form an hourglass-shaped aperture 59.
  • the upper 60 and lower 62 surfaces are engagable with a portion of each of the pins 52 projecting through plate 20. Initially, the upper surface 60 is located in an innermost position, that is, closest to the center axis 26.
  • Yoke 58 includes a pair of guides 64 having an arcuate shape. The guides 64 are positioned such that first ends of each of the guides 64 are spaced further apart than second ends to form a funnel arrangement.
  • the system 10 includes a roller 66 which is rotatably attached to a shaft 70.
  • the guides 64 serve to capture the roller 66 during each rotation of plate 20.
  • Shaft 70 is offset from center axis 26 such that rotation of shaft 70 swings arm 68 through a limited arc.
  • clockwise rotation of the shaft 70 moves the roller 66 closer to the center axis 26 whereas counterclockwise rotation moves the roller 66 farther from the center axis 26.
  • This causes a corresponding upward or downward movement of the yoke 58 in accordance with the position of the roller 66.
  • the position of pins 52 and yoke 58 is maintained by friction during the portion of the rotation of plate 20 when roller 66 is not engaged by guides 64. In accordance with the present invention, this enables periodic adjustment of the magnetic segments 36-50 relative to axis 26.
  • yoke 58 is progressively moved outward and away from the center axis 26.
  • pins 52 associated with magnetic segments 42, 44 will initially engage upper surface 62 and will be moved away from axis 26.
  • yoke 58 sequentially engages pins 52 associated with magnetic segments 40,46, then magnetic segments 38,48 and finally, with magnetic segments 36,50.
  • magnetic segments 36,50 are located closest to the center axis 26 with magnetic segments 38,48 and 40,46 being located progressively further away and magnetic segments 42,44 being located the furthest from the center axis 26 to form an arc shaped configuration.
  • curve 100 (shown as dashed line) which is substantially improved over that of either curve 96 (mid-point of target life) or curve 98 (approaching end of target life) and which approximates that of a new target (curve 94).
  • shaft 70 passes through stationary cover 14 and is coupled to motor 104 through an insulating coupling 102.
  • the power supply 108 such as manufactured by Advanced Energy, Inc. provides sputtering power through cable connection 110.
  • the system 10 also includes a controller 114 which is connected between the power supply 108 and the motor 104 by first 112 and second 116 cables, respectively. It is known that the lifetime of a given target may be expressed in terms of the total amount of energy (kilowatt-hours) it will absorb before replacement of the target is necessary. As such, the magnetic reconfiguration described herein may be automated so as to take place without operator attention. In particular, power usage is transmitted to the controller 114 which may include a microprocessor and memory for storing computer code.
  • the computer code includes lookup tables that correlate preferred positioning of magnetic segments 36-50 for various types of sputtering targets at predetermined stages of target life.
  • the system 10 further includes a position sensor 106 for detecting the position of the shaft 70. This information is also provided to controller 114. Controller 114 then causes activation of motor 104 so as to suitably adjust positioning of yoke 46 via shaft 70 as fourth target 144 erodes. This enables outward movement of the magnetic segments 36-50 as previously described so as to increase rotational dwell near the edge of the fourth target 144 in order to improve film uniforrnity.
  • motor 104 may be a stepper motor and magnetic segments 36-50 may be incrementally adjusted periodically in response to signals generated by controller 114 without reference to sputtering power in an open loop manner.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

Système (10) de pulvérisation cathodique destiné au dépôt d'un film mince sur un substrat (148), qui comporte une chambre (12) dans laquelle le vide peut être fait et dans laquelle est placé le substrat. En particulier, ledit système comporte une cible (144) placée à l'intérieur de la chambre, ladite cible ayant une surface arrière et une surface de pulvérisation (146). Il comporte en outre du plasma destiné à éroder la cible de manière à fournir de la matière servant à former le film mince, l'érosion de la cible se produisant selon un modèle d'érosion prédéterminé et étant commandée par une forme du plasma. Il comporte encore un support (150) destiné à supporter le substrat face à la surface de pulvérisation. Un ensemble aimant produit un champ magnétique sur la cible pour commander la forme du plasma, ledit ensemble étant placé adjacent à la surface arrière. L'ensemble aimant (28) comporte une pluralité d'aimants (36-50) qui peuvent être déplacés dans des positions désirées de manière à modifier la forme de l'ensemble aimant. Cela permet le réglage d'une durée de maintien du champ magnétique sur des parties prédéterminées de la cible pour modifier la forme du plasma et, partant, modifier le modèle d'érosion de la cible.
EP98964215A 1998-12-21 1998-12-21 Cathode a configuration variable des aimants Withdrawn EP1145278A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1998/027250 WO2000038214A1 (fr) 1998-12-21 1998-12-21 Cathode a configuration variable des aimants

Publications (1)

Publication Number Publication Date
EP1145278A1 true EP1145278A1 (fr) 2001-10-17

Family

ID=22268524

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98964215A Withdrawn EP1145278A1 (fr) 1998-12-21 1998-12-21 Cathode a configuration variable des aimants

Country Status (4)

Country Link
EP (1) EP1145278A1 (fr)
JP (1) JP3727849B2 (fr)
KR (1) KR100437867B1 (fr)
WO (1) WO2000038214A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0118803D0 (en) * 2001-08-02 2001-09-26 Bekaert Sa Nv Adjustable magnet configuration and method for magnetron sputtering
JP2006037127A (ja) * 2004-07-23 2006-02-09 Cyg Gijutsu Kenkyusho Kk スパッタ電極構造

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3619194A1 (de) * 1986-06-06 1987-12-10 Leybold Heraeus Gmbh & Co Kg Magnetron-zerstaeubungskatode fuer vakuum-beschichtungsanlagen
US5130005A (en) * 1990-10-31 1992-07-14 Materials Research Corporation Magnetron sputter coating method and apparatus with rotating magnet cathode
EP0555339B1 (fr) * 1990-10-31 1997-12-29 Materials Research Corporation Procede de revetement par pulverisation par magnetron et appareil avec cathode a aimant rotatif
DE4039101C2 (de) * 1990-12-07 1998-05-28 Leybold Ag Ortsfeste Magnetron-Zerstäubungskathode für Vakuumbeschichtungsanlagen
US5188717A (en) * 1991-09-12 1993-02-23 Novellus Systems, Inc. Sweeping method and magnet track apparatus for magnetron sputtering
US5417833A (en) * 1993-04-14 1995-05-23 Varian Associates, Inc. Sputtering apparatus having a rotating magnet array and fixed electromagnets

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0038214A1 *

Also Published As

Publication number Publication date
KR20010108016A (ko) 2001-12-07
JP3727849B2 (ja) 2005-12-21
WO2000038214A1 (fr) 2000-06-29
JP2003531284A (ja) 2003-10-21
KR100437867B1 (ko) 2004-06-30

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