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Electroformed sputtering targetRelated Patent Categories: Chemistry: Electrical And Wave Energy, Non-distilling Bottoms Treatment, Coating, Forming Or Etching By SputteringElectroformed sputtering target description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070246346, Electroformed sputtering target. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE [0001] This application is filed as a continuation of U.S. patent application Ser. No. 10/431,399 to Subramani et al., "ELECTROFORMED SPUTTERING TARGET", commonly assigned to Applied Materials, Inc., which was filed on May 6, 2003 and which is incorporated by reference herein in its entirety. BACKGROUND [0002] The present invention relates to sputtering targets and their methods of manufacture. [0003] A sputtering chamber is used to sputter deposit material onto a substrate to manufacture electronic circuits, such as for example, integrated circuit chips and displays. Typically, the sputtering chamber comprises an enclosure wall that encloses a process zone into which a process gas is introduced, a gas energizer to energize the process gas, and an exhaust port to exhaust and control the pressure of the process gas in the chamber. The chamber is used to sputter deposit a material from a sputtering target onto the substrate, such as a metal for example, aluminum, copper, tungsten or tantalum; or a metal compound such as tantalum nitride, tungsten nitride or titanium nitride. In the sputtering processes, the sputtering target is bombarded by energetic ions, such as a plasma, causing material to be knocked off the target and deposited as a film on the substrate. [0004] In one version, a sputtering target may be formed by holding a sheet of spin-formed sputtering material against the surface of a target backing plate and diffusion-bonding the sputtering material to the backing plate by hot isostatic pressing. However, this method has several disadvantages. The sputtering material required to form the spin-formed sheet typically has to have a high level of purity, and consequently, is expensive. Target fabrication costs are driven even higher because both surfaces of the sheet of sputtering material are typically machined smooth to facilitate diffusion bonding to the underlying backing plate as well as to provide a smooth exposed sputtering surface. Targets formed by such a method can be undesirable because they can have a grain structure that is sheared by the forces generated in the spin-forming process, resulting in non-uniform grain sizes. Also, the targets can have undesirable pores and voids occurring in the bond between the backing plate and sputtering material. During processing, the non-uniform grain size and voids of the target can generate sputtered deposits that are non-uniform or uneven in thickness. The non-uniform and uneven deposition of the sputtered material can result in processed substrates having inferior quality, and can even damage structures formed on the substrate. [0005] It is also difficult to form sputtering targets having convoluted or complex shapes using conventional processes. Targets having complex shapes are often used to provide enhanced sputtering coverage in magnetic fields, as described for example in U.S. Pat. No 6,274,008 to Gopalraja et al., "Integrated Process for Copper Via Filling," commonly assigned to Applied Materials, which is incorporated herein by reference in its entirety. Such targets may comprise for example ridges, projections, rings, troughs, recesses and grooves. Conventional processes such as the spin forming process are not satisfactory in forming complex target shapes, because a significant amount of machining is required to cut out the desired convoluted shape from the spin formed layer. This machining is costly and wastes the expensive high purity sputtering material. Also, excessive machining can generate shearing forces on the surface of the target which plastically deform the grains on the target surface to produce an undesirable surface grain structure. [0006] Thus, it is desirable to form sputtering targets having more uniform and consistent grain surface structure and with fewer voids. It is further desirable to form sputtering targets having complex or non-planar shapes reproducibly and with reduced costs. DRAWINGS [0007] These features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings which illustrate examples of the invention. However, it is to be understood that each of the features can be used in the invention in general, not merely in the context of the particular drawings, and the invention includes any combination of these features, where: [0008] FIG. 1a is a partial sectional schematic side view of a version of a substrate processing chamber; [0009] FIG. 1b is a partial sectional schematic side view of a magnetron suitable for the chamber of FIG. 1a; [0010] FIGS. 2a through 2d are partial sectional schematic side view illustrating stages in electro forming the sputtering target; and [0011] FIG. 3 is a partial sectional schematic side view of a version of an electroplating apparatus for electro forming a target. DESCRIPTION [0012] An exemplary version of a chamber 106 capable of sputter depositing material on a substrate 104 is schematically illustrated in FIG. 1a. The chamber 106 is representative of a self-ionized plasma chamber, such as an SIP+type chamber, developed by Applied Materials, Inc. of Santa Clara, Calif. A typical chamber 106 comprises enclosure walls 118 that include sidewalls, 120, a bottom wall 122 and a ceiling 124. A substrate support 130 is provided to support a substrate 104 in the chamber 106. The substrate support 130 may be electrically floating or may be biased by a pedestal power supply 210, which may be for example an RF power supply 203. The substrate 104 is introduced into the chamber 106 through a substrate loading inlet (not shown) in a sidewall 120 of the chamber 106 and placed on the support 130. The support 130 can be lifted or lowered by support lift bellows (not shown) and a lift finger assembly (also not shown) can be used to lift and lower the substrate 104 onto the support 130 during transport of the substrate 104 into and out of the chamber 106. [0013] A process gas, such as a sputtering gas, is introduced into the chamber 106 through a gas delivery system 150 that includes a process gas supply 152 comprising gas sources 154a-c that each feed a conduit 156a-c having a gas flow control valve 158a-c, such as a mass flow controller, to pass a set flow rate of the gas therethrough. The conduits 156a-c feed the gases to a mixing manifold 160 in which the gases are mixed to from a desired process gas composition. The mixing manifold 160 feeds a gas distributor 162 having one or more gas outlets 164 in the chamber 106. The gas outlets 164 may pass through the chamber sidewalls 120 to terminate about a periphery of the substrate support 130. The process gas may comprise a non-reactive gas, such as argon or xenon, that energetically impinges upon and sputters material from a target 111. The process gas may also comprise a reactive gas, such as one or more of an oxygen-containing gas and a nitrogen-containing gas, that are capable of reacting with the sputtered material to form a layer on the substrate 104. Spent process gas and byproducts are exhausted from the chamber 106 through an exhaust system 168 which includes one or more exhaust ports 170 that receive spent process gas and pass the spent gas to an exhaust conduit 172 in which there is a throttle valve 174 to control the pressure of the gas in the chamber 106. The exhaust conduit 172 feeds one or more exhaust pumps 176. Typically, the pressure of the sputtering gas in the chamber 106 is set to sub-atmospheric levels. [0014] The sputtering chamber 106 further comprises a sputtering target 111 facing a surface 105 of the substrate 104. The target 111 can be a planar target (not shown) or a non-planar target (shown). The sputtering chamber 106 can also comprise a shield 128 to protect a wall 118 of the chamber 106 from sputtered material, and typically, to also serve as an anode with respect to the cathode target 111. The shield 128 may be electrically floating or grounded. The target 111 is electrically isolated from the chamber 106 and is connected to a target power supply 200, such as a pulsed DC power source, but which may also be other types of voltage sources. In one version, the target power supply 200, target 111, and shield 128 operate as a gas energizer 180 that is capable of energizing the sputtering gas to sputter material from the target 111. The target power supply 200 applies a bias voltage to the target 111 relative to the shield 128. The electric field generated in the chamber 106 from the voltage applied to the sputtering target 111 energizes the sputtering gas to form a plasma that energetically impinges upon and bombards the target 111 to sputter material off the target and onto the substrate 104. A suitable pulsing frequency of a pulsed DC voltage for energizing the process gas may be, for example, at least about 50 kHz, and more preferably less than about 300 kHz, and most preferably about 100 kHz. A suitable DC voltage level to energize the process gas may be, for example, from about 200 to about 800 Volts. [0015] The chamber 106 further comprises a magnetron 300 comprising a magnetic field generator 301 that generates a magnetic field near the target 111 of the chamber 106 to increase an ion density in a high-density plasma region 226 adjacent to the target 111 to improve the sputtering of the target material, as shown in FIGS. 1a and 1b. An improved magnetron 300 may be used to allow sustained self-sputtering of copper or sputtering of aluminum, titanium, or other metals--while minimizing the need for non-reactive gases for target bombardment purposes, as for example, described in U.S. Pat. No. 6,183,614 to Fu, entitled "Rotating Sputter Magnetron Assembly"; and U.S. Pat. No. 6,274,008 to Gopalraja et al., entitled "Integrated Process for Copper Via Filling," both of which are incorporated herein by reference in their entirety. The magnetic field extends through the substantially non-magnetic target 111 into the sputtering chamber 106. In one version, the improved magnetron 300 comprises a magnetic field generator 301 having magnets 307 that extend along one or more sidewalls of the target 111 and are connected by a magnetic yoke 310, as shown in FIG. 1b. The magnets 307 may comprise one or more of an inner magnet and outer magnet that are connected together by a yoke 310 that is formed of a magnetically soft material. The magnetic field generator 301 comprising the magnets 307 provides an enhanced magnetic field 309 in the region 226 enclosed by the target sidewalls, thereby increasing the density of the plasma in the region 226. In another version, the magnetron 300 comprises a motor 306 to rotate the magnetron 300 about a rotation axis 312 to provide an enhanced magnetic field, as shown in FIG. 1b. The motor 306 is typically attached to the magnetic yoke 310 of the magnetron 300 by a shaft 308 that extends along the rotation axis 312. [0016] The chamber 106 can be operated by a controller 311 comprising a computer that sends instructions via a hardware interface to operate the chamber components, including the substrate support 130 to raise and lower the substrate support 130, the gas flow control valves 158a-c, the gas energizer 180, and the throttle valve 174. The process conditions and parameters measured by the different detectors in the chamber 106, or sent as feedback signals by control devices such as the gas flow control valves 158a-c, pressure monitor (not shown), throttle valve 174, and other such devices, are transmitted as electrical signals to the controller 311. Although, the controller 311 is illustrated by way of an exemplary single controller device to simplify the description of present invention, it should be understood that the controller 311 may be a plurality of controller devices that may be connected to one another or a plurality of controller devices that may be connected to different components of the chamber 106--thus, the present invention should not be limited to the illustrative and exemplary embodiments described herein. [0017] In one version, a target 111 suitable for use in a sputtering chamber 106 comprises a complex shape, such as a shape comprising a non-planar surface 24, as shown in FIGS. 1a and 1b. The target 111 is typically circularly symmetric with respect to a main vertical axis of the chamber 106, and may comprise ridges, projections, rings, troughs, recesses, grooves or other topological features that enhance processing of the substrates 104. A target 111 having a complex shape has been discovered to provide improved sputtering properties, as described for example in aforementioned U.S. Pat. No. 6,274,008. The target 111 having the complex shape provides improved process performance by accommodating magnets 307 in proximity to and surrounding high density plasma regions 226 adjacent to the target 111, as shown in FIGS. 1a and 1b, or by otherwise providing for an enhanced magnetic field 309 that allows for a large thickness or volume of a sputtering plasma in high density plasma regions 226 adjacent to the target 111. The target 111 having the complex shape may also serve to improve deposition uniformity by regulating the effective target area to which portions of the substrate are exposed. For example, a recessed portion of the target 111, such as a trough 8, may be effectively hidden from regions of the substrate 104 that are more distant from the recessed portion, such as an outer edge 103 of the substrate 104, and thus deposition of material from the recessed portion onto the more distant regions of the substrate 104 may be reduced. [0018] The target 111 comprises an inverted annular trough 8 comprising cylindrical outer and inner sidewalls 4,6 and a top wall 5 that at least partially enclose a high density region 226. The annular trough 8 encircles a central portion of the target 111 comprising a cylindrical well 7 that projects downwards towards the surface 105 of the substrate 104. The cylindrical inner sidewall 6 defines the sides of the cylindrical well 7, and the cylindrical well 7 is capped by a bottom wall 9 that faces the substrate 104. The bottom wall 9 and top walls 5 can be substantially parallel to the surface 105 of the substrate 104, and the inner and outer sidewalls 4,6 can be substantially perpendicular to the surface 105 of the substrate 104. At least a portion of the surface 24 of the side, top and bottom walls 4,5,6,9, comprises the sputtering material to be sputtered on the substrate 104. The inverted annular trough 8 and cylindrical well 7 can accommodate magnets 307 positioned between the outer sidewall 4 of the trough and the sidewall 120 or ceiling 124 of the chamber enclosure 118 and even within the space enclosed between the bottom and sidewalls 9, 6 of the cylindrical well 7 and ceiling 124 of the chamber enclosure 118, thereby providing an enhanced magnetic field 309 in the regions 226 adjacent to the target 111. The target 111 may further comprise a flange portion 13 that extends radially outward from the outer sidewall 4 to attach the target 111 to the chamber enclosure walls 118, for example by vacuum sealing the flange portion 13 of the target 111 between the ceiling 124 and sidewalls 120 of the chamber 106. [0019] The target 111 can be formed in an electro forming process in which sputtering material is electroplated to form a complex or non-planar shape. Electro forming provides a sputtering material having a high purity and good grain properties, such as a higher uniformity of grain size. Electro forming can also generate a unitary sputtering material structure having fewer pores or voids. The method is suitable for forming targets 111 having sputtering material comprising, for example, one or more of copper, aluminum, tantalum, titanium and tungsten. The method generally comprises forming a preform 14 having a surface 16 and electroplating a layer 12 of sputtering material onto the surface 16 of the perform to form the sputtering target 111. FIGS. 2a through 2d schematically illustrate stages in an embodiment of a target fabrication process. [0020] The target preform 14 provides a support structure on which the layer 12 of sputtering material can be electroplated, as shown in FIG. 2a. The preform 14 can comprise the same or a different material than the sputtering material. In one version, the preform 14 comprises a material that is more easily shaped than the sputtering material, and may also be of lower purity or less expensive than the sputtering material. The preform 14 is desirably formed from a material that is readily electroplated by the sputtering material, such as for example, a conducting or semi conducting material that can serve as an anode in an electroplating process. A suitable preform 14 may comprise, for example a metal, such as at least one of aluminum, copper, steel and titanium. For example, the preform 14 may comprise an industrial grade copper alloy. In one method of forming the preform 14, the metal material is heated to a molten state and poured into a mold having the desired preform shape. Cooling of the molten metal in the mold results in the preform 14 having the desired shape. The molded metal can also be machined or otherwise shaped to form features in the target preform 14. Continue reading about Electroformed sputtering target... Full patent description for Electroformed sputtering target Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electroformed sputtering target patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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