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  Iridium oxide nanostructure patterningUSPTO Application #: 20060088993Title: Iridium oxide nanostructure patterning Abstract: A method is provided for patterning iridium oxide (IrOx) nanostructures. The method comprises: forming a substrate first region adjacent a second region; growing IrOx nanostructures from a continuous IrOx film overlying the first region; simultaneously growing IrOx nanostructures from a non-continuous IrOx film overlying the second region; selectively etching areas of the second region exposed by the non-continuous IrOx film; and, lifting off the IrOx nanostructures overlying the second region. Typically, the first region is formed from a first material and the second region from a second material, different than the first material. For example, the first material can be a refractory metal, or refractory metal oxide. The second material can be SiOx. The step of selectively etching areas of the second region exposed by the non-continuous IrOx film includes exposing the substrate to an etchant that is more reactive with the second material than the IrOx. (end of abstract) Agent: Sharp Laboratories Of America, Inc. C/o Law Office Of Gerald Maliszewski - San Diego, CA, US Inventors: Fengyan Zhang, Gregory M. Stecker, Robert A. Barrowcliff, Sheng Teng Hsu USPTO Applicaton #: 20060088993 - Class: 438618000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Coating With Electrically Or Thermally Conductive Material, To Form Ohmic Contact To Semiconductive Material, Contacting Multiple Semiconductive Regions (i.e., Interconnects) The Patent Description & Claims data below is from USPTO Patent Application 20060088993. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a continuation-in-part of a pending patent application entitled, IRIDIUM OXIDE NANOTUBES AND METHOD FOR FORMING SAME, invented by Zhang et al., Ser. No. 10/971,280, filed Oct. 21, 2004. [0002] This application is a continuation-in-part of a pending patent application entitled, IRIDIUM OXIDE NANOWIRE AND METHOD FOR FORMING SAME, invented by Zhang et al., Ser. No. 10/971,330, filed Oct. 21, 2004. [0003] Both the above-mentioned applications are incorporated herein by reference. BACKGROUND OF THE INVENTION [0004] 1. Field of the Invention [0005] This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to patterned iridium oxide nanostructures and an associated fabrication process. [0006] 2. Description of the Related Art [0007] Recently, the fabrication of nanostructures has been explored, due to its potential importance as a building block in nano, microelectromechanical (MEM), and nanoelectromechanical NEM device applications. For example, researchers associated with Charles Lieber have reported the synthesis of a variety of semiconductor nanowires made from materials such as silicon (Si), Si-germanium (SiGe), InP, and GaN, and use in building nano-computing system. Other groups have reported using templates structures to grow metallic nanowires made of materials such as Ni, NiSi, Au, and Pt. Metallic nanowires can be used as interconnections and the sharp tips of the nanowire make them effective for field emission purpose. ZnO.sub.2 nanowires are potentially useful as a light emission element. [0008] IrO.sub.2 is a conductive metal oxide that is already widely used in DRAM and FeRAM applications. IrO.sub.2 can be used as a conductive electrode, as it has stable electrical and chemical properties, even at high temperature O.sub.2 ambient conditions. IrO.sub.2 can also be used as pH sensor material. Ir thin film can be deposited using PVD easily with excellent polycrystalline structure and strong (111) orientation. IrO.sub.2 can be formed afterwards, by oxidizing the Ir film, or it can be formed directly using reactive sputtering method at higher temperatures in oxygen ambient. CVD methods have recently been developed to grow Ir and IrO.sub.2 thin films. It is relatively easy to maintain good composition control in CVD processes, and the method is know to provide good step coverage on some materials. [0009] No processes had been previously reported that are able to form metallic nanowires without the use of porous material forms or templates. The templates add a considerable degree of complexity to the process. Thus, a more practical and commercially feasible means of forming metallic nanowires publications is desirable. To that end, the above-mentioned Related Applications describe the growth of iridium oxide (IrO.sub.2) nanostructures formed using a metalorganic chemical vapor deposition (MOCVD) method without a template. The Related Applications describe an efficient MOCVD process for forming nanotips and nanorods. Using these MOCVD processes, IrO2 has been successfully grown on Ti, TiN, TaN and SiO2 substrates. The growth length, density, and vertical orientation can be controlled by temperature, pressure, flow, substrates, and time. [0010] It would be advantageous if iridium oxide nanostructures, however formed, could be selectively formed or patterned on a substrate. [0011] It would be advantageous if iridium oxide nanostructures could be selectively formed on a substrate, taking advantage of the differences in characteristics of adjoining substrate materials. [0012] It would be advantageous if iridium oxide nanostructures could be selectively formed on a substrate, taking advantage of the differences in the manner in which iridium oxide covers adjoining substrate materials. SUMMARY OF THE INVENTION [0013] Now that it has been shown that nanotips and nanorods can be efficiently formed using conventional CMOS processes, the next step is to investigate means of forming practical iridium oxide nanotip structures. To that end, this application describes a process for patterning IrO2 nanorods, so that they can be seamlessly integrated into CMOS, IC, and liquid crystal display (LCD) devices. [0014] Accordingly, a method is provided for patterning iridium oxide (IrOx) nanostructures. The method comprises: forming a substrate first region adjacent a second region; growing IrOx nanostructures from a continuous IrOx film overlying the first region; simultaneously growing IrOx nanostructures from a non-continuous IrOx film overlying the second region; selectively etching areas of the second region exposed by the non-continuous IrOx film; lifting off the IrOx nanostructures overlying the second region; and, in response to lifting off the IrOx nanostructures overlying the second region, forming a substrate with nanostructures overlying the first region. [0015] Typically, the first region is formed from a first material and the second region from a second material, different than the first material. For example, the first material can be a refractory metal, or refractory metal oxide. The second material can be SiOx. [0016] The step of selectively etching areas of the second region exposed by the non-continuous IrOx film includes exposing the substrate to an etchant that is more reactive with the second material than the IrOx. For example, if the first material is a refractory metal and the second material is SiO2, then HF or buffered oxide etches (BOE) are suitable etchants. [0017] In one aspect, the step of forming a substrate first region adjacent a second region includes: conformally depositing the second material overlying the first and second regions; and, selectively forming the first material overlying the second material in the first region. In a second aspect, the step of forming a substrate first region adjacent a second region includes: conformally depositing the second material overlying the first and second regions; selectively forming the first material with a surface overlying the second material in the first region; conformally depositing the second material overlying the first and second regions; and, chemical-mechanical polishing (CMP) the second material to the level of the first material surface. [0018] Additional details of the above-described method and a corresponding patterned substrate with IrOx nanostructures are described below. BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 is a partial cross-sectional view of a patterned iridium oxide (IrOx) nanostructure substrate. [0020] FIG. 2 is a partial cross-sectional view of a variation of the patterned substrate of FIG. 1. Continue reading... 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