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
  • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
  • H01J37/3405—Magnetron sputtering
  • H01J37/3408—Planar magnetron sputtering
• • 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
  • H01J37/3411—Constructional aspects of the reactor
  • H01J37/345—Magnet arrangements in particular for cathodic sputtering apparatus
  • H01J37/3455—Movable magnets

Definitions

• the present invention is directed to a method and apparatus for depositing metal and metal-reactive gas coatings onto a substrate.
• RF diode sputtering conventionally accomplished by radio frequency (“RF") diode sputtering from a ceramic target. While somewhat effective, the RF diode sputtering process is quite slow with deposition rates of approximately 500 Angstroms/Minute. With such low deposition rates batch loading is required for economic machine throughput.
• RF radio frequency
• Batch processing involves coating multiple substrates in a single deposition run.
• batch processing has long been recognized by the semiconductor industry as less- than optimum because of several factors.
• the Ar + ions accelerate towards the negatively charged target and collide with the target to release Al atoms that are deposited
• magnets creates a "trenching" of the target which results in a non-uniform erosion of the target. This is disadvantageous because utilizing a non-uniform erosion pattern increases
• the magnetic path is a double-lobe structure that includes first and second lobes that are symmetrical about an axis in the plane of the plate that intersects a center of rotation of the plate.
• the magnets are arranged in several rows.
• a first row of magnets has a double-lobe structure that corresponds to the first and second lobes of the magnetic path.
• Second and third rows of magnets are arranged in the shape of a rings inside the first and second lobes of the magnetic path magnetic path.
• the lobe structure is designed to maximize the erosion of the perimeter region of a sputtering target.
• the lobe structure can be circular or elliptical in shape.
• the sputtering system includes a metal sputtering
• the sputtering system also includes a rotatable magnet array disposed over the sputtering target.
• the magnet array can be shaped as in the embodiments described above. With this magnet array, the resulting magnetic path generates a substantially uniform erosion of the sputtering target.
• a magnet array such as the magnet arrays described in the preceding embodiments, is
• Fig. 2 is a schematic view of a magnet array according to another embodiment of
• Fig. 3 is a schematic view of a magnet array according to another embodiment of the present invention.
• Fig. 6 is a schematic view of a sputtering system according to an embodiment of the
• Fig. 7 is a schematic view of a sputtering source according to another embodiment of the present invention.
• Fig. 8 is a schematic view of a sputtering target according to an embodiment of the present invention.
• the present invention provides a sputtering system and magnet array for depositing metal and metal-reactive gas coatings onto a substrate.
• the metal-reactive gas coatings can be electrically conductive or insulating.
• the magnet array is designed for use in a rotating magnetron.
• the magnet array and sputtering system of the present invention are used for the high rate deposition of a dielectric material, such as an Aluminum Oxide coating, on a substrate. While the embodiments described herein are used to deposit Aluminum Oxide coatings on a silicon wafer substrate, the present invention is not limited for use with this particular coating or substrate, as would be apparent to one skilled in the art given the present description.
• the polarity of the magnets comprising outer rows 106 and 107 is North ("N") and the polarity of the magnets comprising inner rings
• 108 and 110 is South ("S").
• the polarity of the magnets in the outer and inner rings can be switched.
• a center magnet 114 can be utilized having the same polarity as inner rings 108 and 110.
• Center magnet 114 can be disposed directly over the axis of rotation.
• a center magnet set (such as shown in Fig. 3, described below) comprising two or more magnets can be disposed over the axis of rotation.
• a center magnet or center magnet set can be used to further control the resulting erosion
• the magnets comprising magnet array 100 are all of the same magnetic field strength.
• the magnets comprise rare-earth
• Neodimium Iron Boron (NdFeB) magnets such as Neodimium Iron Boron (NdFeB) magnets. These magnets have high pole
• the example magnets shown in Fig. 1 each have a rectangular shape.
• the magnets utilized in magnet array 100 can comprise any shape, such as rectangular, square, or circular shapes.
• a continuous erosion track or closed-loop erosion path 112 is formed between outer rows 106 and 107 and inner rows 108 and 110.
• the erosion track resembles a " figure-8 " (corresponding to the space between the outer and inner rows of magnets). Flux from one row of magnets to the other forms a tunnel. When sputtering, an intense plasma forms in the tunnel, and by rotating the magnet array, the plasma is swept around the surface of the target. Thus, when magnet array 100 is rotated, the sputter target surface is eroded over nearly the entire available surface area.
• Figs. 4A-4C where the resulting erosion pattern on the target follows the measured field strength when the magnet array is not rotating.
• FIGS. 4A-4C show that the erosion track is substantially uniform, with varying field strengths of + 10 % at all points greater than 0.5
• Magnet array 150 comprises a plurality
• Lobe 152 includes an outer row of magnets 156 and an inner ring of
• FIG. 5A-5C The magnetic field strength profiles perpendicular to the sputtering target surface for magnet array 150 are shown graphically in Figs. 5A-5C, where the resulting erosion pattern on the target follows the measured field strength when the magnet array is not rotating. Similar to Figs. 4A-4C, these measurements were taken with a conventional magnetic field probe at a predetermined distance from the surface. The field strength was measured as a function of radial distance from the center out towards the edge along an
• Magnet array 170 comprises of plurality of magnets disposed on plate 101 that can be rotated about an axis, which corresponds to the center of rotation of plate 101.
• This design utilizes two circular magnetic lobes 172, 174 that are symmetric about the C-axis.
• Lobe 172 includes an outer row of magnets 176 and an inner ring of magnets 178.
• Lobe 174 is shown in FIG. 3.
• two magnets are disposed surrounding and proximate to (in this example, on either side of) the center of rotation of plate 101.
• Magnet set 184 can be used to control the resulting erosion profile of a target, in this case by blocking the inner erosion of the target.
• the elliptical lobe pattern of magnet array 100 of Fig. 1 is designed so that the curvature of the outer regions of magnet rows 106, 107, 108, and 110 have a flatter (as opposed to a more circular) shape, thereby increasing the rate from the edge of the target.
• the double-lobe, elliptical design of magnet array 100 a greater magnetic field is available for eroding the target, as compared to conventional designs that use a single lobe that is asymmetrical with respect to the axis of rotation.
• the more circular lobe design of magnet array 150 may be useful depending on the type of material being deposited on the substrate.
• the symmetrical and dual-lobe design of magnet arrays 100, 150, and 170 generates an increased sputter rate (i.e., the amount of target sputtered off per unit time). According
• the magnet array design should minimize the area of the target that is not sputtering. Otherwise, the target may accumulate material and begin to arc, which is damaging to the sputtering system.
• another design parameter of the present invention is based, at least in part, on the discovery by the inventors that the erosion profile in a reactive environment differs from that in a non-reactive environment. Thus, magnet array designs optimized for metal deposition may not be necessarily well suited for reactive applications.
• Cathode assembly 202 includes a source, such as conventional power supply (not shown) to activate the sputtering process.
• the target 220 is charged by the source to act as the cathode for the sputtering system.
• Target 220 can comprise any metal
• target 220 is an aluminum plate shaped like an annulus. Target 220 is discussed in greater detail with respect to Fig. 8.
• a motor 203 is coupled to a belt 204 which rotates a shaft 205 about axis of rotation 207 in a conventional manner.
• a spindle 206 can be used to mount magnet array 210.
• magnet array 210 can comprise a magnet array 100, magnet array 150, or magnet array 170 discussed above or a variation based on the teachings herein.
• Motor 203 can have an adjustable speed. In operation, the spindle 206 rotates magnet array 210 to create a rotating field at the sputtering target surface.
• Sputtering system 200 further includes a backing plate 216.
• backing plate 216 is electrically isolated and water cooled.
• Target 220 is attached or bonded to backing plate 216.
• the backing plate/target assembly is mounted to a vacuum chamber 250 such that the target surface 221 is positioned opposite the substrate 230 to be coated.
• the outside surface of the backing plate is placed at atmospheric pressure and positioned in front of magnet array 210.
• a sputter gas medium such as Ar gas
• Ionized Ar + atoms are attracted to the negatively charged target 220 during the sputtering process.
• a portion of the released Al atoms will eventually deposit on substrate 230, which is supported by lower electrode 240.
• electrode 240 includes a moveable platform that provides height adjustment for the substrate and allows for process repeatability.
• conventional magnetron control equipment (not shown), such as ion gauges, control computers, valve controllers, etc., can be utilized to optimize process repeatability, as will become apparent to those of skill in the art given the present description.
• sputtering system 200 further includes a reactive gas injection unit 235 to provide for the introduction of a reactive gas, such as Oxygen or Nitrogen.
• a reactive gas such as Oxygen or Nitrogen.
• the O 2 reacts with the Al atoms released during the sputtering process to form a dielectric or insulating coating of Al 2 O 3 on the substrate 230.
• a coating such as titanium nitride, can be used to coat substrate 230.
• the reactive gas injection system 235 can include a shower ring injector to provide for the uniform introduction of the gas proximate to the exposed surface of substrate 230.
• Main vacuum chamber 250 can be a conventional vacuum system capable of
• Fig. 7 schematically shows a more detailed view of several additional embodiments of sputtering system 200.
• Magnet array 210 is positioned over target 220, which is shaped as an annulus.
• target 220 is attached or bonded by conventional means to a liquid-cooled backing plate 216.
• Water, or other types of coolant can be fed to a copper (or the like) backing plate 216 through coolant feed line 217, which is in fluid communication with a coolant conduit (not shown) in contact with backing plate 216.
• Cooling is important because during the sputtering process, the majority of the power applied to the target is converted to heat. Cooling also helps prevent the target from becoming de-bonded with backing plate 216. Further, by providing target cooling, sputtering source 200 can be temperature controlled during high rate sputtering
• Sputtering system 200 also provides several alternative mechanisms for injecting a sputter gas medium, such as Ar, into the reaction chamber for sputtering.
• sputtering system 200 includes a gas feed 225 which can be used to inject Ar gas substantially parallel to or across the surface of target 220. Gas flows from feed 225 along a first gas path or conduit 226 to a gas introduction port 228 located proximate to the central region of target 220. From gas introduction port 228, Ar gas can flow radially outward across the surface of the target 220, to further help provide uniform sputtering of the target.
• sputtering system 200 include a perimeter gas feed 227, which is used to introduce Ar across the surface of target 220 from the perimeter of the target inward towards the central region along path 229.
• the perimeter gas feed 227 can be coupled to a conventional shower ring injector which is disposed outside the perimeter of target 220 and directs gas flow inward towards the central region of target 220.
• Ar gas, or the like can be introduced to the reaction chamber utilizing the above-mentioned mechanisms, either alone or in combination.
• Fig. 8 shows an embodiment where a metal target 300 to be used with the magnet array and sputtering system of the present invention.
• Metal target 300 is an annulus shaped structure composed of the target metal to be deposited on the substrate.
• the target can be configured to resemble an annulus, where the hole in central region 302 corresponds to the central dead spot.
• a sputtering system similar to that shown in Figs. 6 and 7, was utilized to perform several experimental coating runs on silicon wafer substrate.
• An aluminum target was utilized having a shape similar to that shown for target 300 in Fig. 8. The outer diameter of the target was approximately 11.5 inches and the inner diameter was approximately 2.5 inches.
• a magnet array similar in shape to magnet array 100 from Fig. 1 was utilized.
• the magnet array was disposed on a 12 inch diameter circular plate and included 47 NdFeB magnets arranged in a symmetrical dual-lobe pattern, with each lobe having an elliptical shape.
• Each NdFeB magnet was rectangular shaped with a length of about 1 inch and a width of about 0.5 inches, with each having a magnetic pole field of about 5000 Gauss.
• the outer row of each lobe was N-polarized and the inner rows were S-polarized.
• each lobe was separated by about 20 mm.
• a conventional pulsed DC plasma generator was used to supply about 4 KWatts of power to the sputtering target.
• the reactive gas (O 2 ) was introduced to the reaction chamber via a gas introduction system

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• Mechanical Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physical Vapour Deposition (AREA)
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• 1999
  • 1999-09-29 US US09/406,853 patent/US6258217B1/en not_active Expired - Lifetime
• 2000
  • 2000-09-27 HK HK03101395.6A patent/HK1049502A1/zh unknown
  • 2000-09-27 EP EP00966934A patent/EP1235945B1/en not_active Expired - Lifetime
  • 2000-09-27 JP JP2001527013A patent/JP2003510464A/ja active Pending
  • 2000-09-27 DE DE60040757T patent/DE60040757D1/de not_active Expired - Lifetime
  • 2000-09-27 AU AU77207/00A patent/AU7720700A/en not_active Abandoned
  • 2000-09-27 WO PCT/US2000/026503 patent/WO2001023634A1/en not_active Ceased
  • 2000-09-27 AT AT00966934T patent/ATE413688T1/de not_active IP Right Cessation

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