UNITED STATES PATENT AND TRADEMARK OFFICE
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`SAMSUNG ELECTRONICS CO., LTD.,
`SAMSUNG ELECTRONICS AMERICA, INC.,
`Petitioners,
`
`v.
`
`NANOCO TECHNOLOGIES LTD.,
`Patent Owner.
`
`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`PATENT OWNER’S RESPONSE
`PURSUANT TO 37 C.F.R. § 42.120
`
`REDACTED VERSION
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`

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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`B.
`
`TABLE OF CONTENTS
`INTRODUCTION AND SUMMARY OF ARGUMENT .............................. 1
`I.
`OVERVIEW OF QUANTUM DOT NANOPARTICLES ............................. 3
`II.
`IDENTIFICATION OF INSTITUTED GROUNDS ...................................... 7
`III.
`IV. OVERVIEW OF SEMICONDUCTOR NANOPARTICLE
`SYNTHESIS METHODS ............................................................................... 8
`A.
`Nanorods and Nanowires ...................................................................... 9
`1.
`The Vapor-Liquid-Solid Method ................................................ 9
`2.
`The Solution-Liquid-Solid Method .......................................... 12
`Quantum Dots ...................................................................................... 15
`1.
`The Hot-Injection Method ........................................................ 15
`2.
`The Heat-Up Method ................................................................ 18
`3.
`The Molecular Cluster-Assisted Method .................................. 19
`4.
`The Solid-State Method ............................................................ 21
`5.
`Other Methods ........................................................................... 21
`THE CHALLENGED ’365 PATENT ........................................................... 22
`V.
`VI. CLAIM CONSTRUCTION .......................................................................... 23
`A. Molecular Cluster Compound ............................................................. 24
`VII. PETITIONER HAS NOT SHOWN THAT THE CHALLENGED
`CLAIMS ARE UNPATENTABLE .............................................................. 25
`A.
`Ground 1: No Claims Are Anticipated by Banin ................................ 25
`1.
`Banin Does Not Disclose a Molecular Cluster Compound ...... 26
`
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`a.
`
`b.
`
`Banin’s gold catalysts were made according to the
`Hutchison process, which creates gold particles
`that are not sufficiently well-defined .............................. 27
`Dr. Green’s testimony that Banin’s gold clusters
`are molecular cluster compounds is refuted by his
`own deposition testimony, and the testimony of
`other witnesses. ............................................................... 32
`The Yu Reference ..................................................................... 37
`Banin Teaches Away From Using Conditions Permitting
`Seeding and Growth in SLS Reactions ..................................... 40
`Ground 2: Claims 1, 7-12, 15-17 and 22-23 Are Not Rendered
`Obvious by Banin ................................................................................ 42
`Ground 3: Claims 2-6 and 18-21 Are Not Rendered Obvious by
`Banin in View of Herron ..................................................................... 43
`Ground 4: Claims 13 and 14 Are Not Rendered Obvious by
`Banin in View of Treadway ................................................................ 51
`Ground 5: Claims 1-9 and 17-23 Are Not Rendered Obvious by
`Zaban in View of Farneth and Yu ....................................................... 52
`1.
`A Person of Skill in the Art Would Not Combine Zaban’s
`Group III-V Quantum Dot Process with Farneth’s Group
`II-VI Solid-state Intermediate ................................................... 52
`A Person of Skill in the Art Would Not Swap Zaban’s
`Zinc Acetate for Farneth’s 10-Zinc Precursor Because It
`Would Change the Nature of Zaban’s Quantum Dots .............. 54
`Petitioner’s purported motivation does not come from
`any of the references ................................................................. 56
`Grounds 6 and 7: Claims 1, 2, 4, 7-12, 17-18, and 22-23 Are
`Not Rendered Obvious by Lucey in View of Ahrenkiel ..................... 58
`
`2.
`3.
`
`2.
`
`3.
`
`B.
`
`C.
`
`D.
`
`E.
`
`F.
`
`ii
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`1.
`
`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`2.
`
`Lucey Uses the Hot-Injection Method to make Quantum
`Dots, While Ahrenkiel Uses the SLS Method to Make
`Quantum Rods ........................................................................... 58
`Even Replacing Lucey’s Precursor with Ahrenkiel’s
`Multiple Precursors Would Not Practice the Claims of
`the ’365 Patent Because Both of Ahrenkiel’s Precursors
`Provide the Ions to Be Incorporated into the
`Semiconductor Core .................................................................. 60
`Lucey Expressly Teaches Away from Ahrenkiel’s
`Chlorine-Based Precursors ........................................................ 62
`There Is No Motivation to Combine Lucey and
`Ahrenkiel, and No Reasonable Expectation of Success ........... 63
`VIII. CONCLUSION .............................................................................................. 65
`
`3.
`
`4.
`
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`TABLE OF AUTHORITIES
`
` Page(s)
`
`Cases
`In re Am. Acad. of Sci. Tech Ctr.,
`367 F.3d 1359 (Fed. Cir. 2004) .......................................................................... 48
`In re Fine,
`837 F.2d 1071 (Fed. Cir. 1988) .................................................................... 52, 58
`In re Fritch,
`972 F.2d 1260 (Fed. Cir. 1992) .................................................................... 52, 58
`In re NuVasive, Inc.,
`842 F.3d 1376 (Fed. Cir. 2016) .................................................................... 52, 57
`Kinetic Concepts, Inc. v. Smith Nephew, Inc.,
`688 F.3d 1342 (Fed. Cir. 2012) .......................................................................... 43
`Nidec Motor Corp. v. Zhongshan Broad Ocean Motor Co.,
`868 F.3d 1013 (Fed. Cir. 2017) .......................................................................... 24
`Otsuka Pharmaceutical Co., Ltd. v. Sandoz, Inc.,
`678 F.3d 1280 (Fed. Cir. 2012) .......................................................................... 50
`Phillips v. AWH Corp.,
`415 F.3d 1303 (Fed. Cir. 2005) (en banc) .......................................................... 23
`Samsung Electronics Co., Ltd. et al v. Red Rock Analytics, LLC,
`IPR2018-00555, Paper 16 (PTAB Aug. 30, 2018) ............................................. 49
`Sanofi-Synthelabo v. Apotex, Inc.,
`550 F.3d 1075 (Fed. Cir. 2008) .................................................................... 52, 58
`Statutes and Regulations
`U.S.C. §102 ................................................................................................................ 7
`U.S.C. §103 ................................................................................................................ 7
`37 C.F.R. § 42.65 ..................................................................................................... 48
`
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`37 C.F.R. § 42.100(b) .............................................................................................. 23
`MPEP § 2143.01 ...................................................................................................... 50
`
`v
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`Exhibit
`2001
`2002
`2003
`2004
`
`2005
`
`2006
`
`2007
`
`2008
`
`2009
`
`2010
`
`2011
`
`2012
`
`2013
`
`2014
`
`TABLE OF EXHIBITS
`
`Description
`Declaration of Michael C. Newman
`Declaration of Thomas H. Wintner
`Declaration of Matthew S. Galica
`Periodic table of the elements, Encyclopaedia Britannica, Inc.,
`available at https://www.britannica.com/science/periodic-table (last
`visited Feb. 18, 2021)
`Samsung Global Newsroom. Quantum Dot Artisan: Dr. Eunjoo Jang,
`Samsung Fellow, November 30, 2017
`ACS Energy Lett. 2020, 5, 1316-1327. “Environmentally Friendly
`InP-Based Quantum Dots for Efficient Wide Color Gamut Displays”
`Wang, F., Dong, A. and Buhro, W.E., Solution–liquid–solid
`synthesis, properties, and applications of one-dimensional colloidal
`semiconductor nanorods and nanowires. Chemical
`Reviews, 116(18):10888-10933 (2016).
`Wang, F., et al., Solution− liquid− solid growth of semiconductor
`nanowires. Inorganic chemistry, 45(19):7511-7521 (2006).
`Madkour, L.H., Synthesis Methods For 2D Nanostructured
`Materials, Nanoparticles (NPs), Nanotubes (NTs) and Nanowires
`(NWs). In Nanoelectronic Materials (pp. 393-456). Springer, Cham.
`(2019)
`Mushonga, P., et al., Indium phosphide-based semiconductor
`nanocrystals and their applications. Journal of Nanomaterials, 1-11
`(2012).
`Luo, H., Understanding and controlling defects in quantum confined
`semiconductor systems, Doctoral dissertation, Kansas State
`University (2016).
`Sinatra, L., et al. Methods of synthesizing monodisperse colloidal
`quantum dots. Material Matters, 12:3-7 (2017)
`Pu, Y., et al., Colloidal synthesis of semiconductor quantum dots
`toward large-scale production: a review. Industrial & Engineering
`Chemistry Research, 57(6):1790-1802 (2018).
`Rao, C. N. R.; Gopalakrishnan, J., Chapter 3: Preparative Strategies
`from New Directions in Solid State Chemistry; Cambridge University
`Press: Cambridge, UK (1986).
`
`vi
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`REDACTED VERSION
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`

`

`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`Exhibit
`2015
`
`2016
`
`2017
`
`2018
`
`2019
`
`2020
`
`2021
`
`2022
`
`2023
`
`2024
`
`2025
`
`2026
`
`Description
`Glossary of Common Wafer Related Terms, BYU Electrical &
`Computer Engineering Integrated Microfabrication Lab, definition of
`degenerate semiconductor, available at
`https://cleanroom.byu.edu/ew_glossary (last visited Feb. 19, 2021)
`October 22, 2006 email between Eunjoo Jang and Nigel Pickett Re:
`Cd free quantum dots
`Weare, W.W., Reed, S.M., Warner, M.G. and Hutchison, J.E.,
`Improved synthesis of small (d core≈ 1.5 nm) phosphine-stabilized
`gold nanoparticles. Journal of the American Chemical
`Society, 122(51):12890-12891 (2000).
`Samsung’s Motion to Stay Pending Inter Partes Review of the
`Asserted Patents in Case 2:20-cv-00038-JRG, filed on November 30,
`2020
`Order denying Samsung’s Motion to Stay Pending Inter Partes
`Review in Case 2:20-cv-00038-JRG, filed on January 8, 2021
`Standing Order Regarding the Novel Coronavirus (Covid-19) for the
`Eastern District of Texas Marshall Division, signed March 3, 2020
`Standing Order Regarding Pretrial Procedures In Civil Cases
`Assigned to Chief District Judge Rodney Gilstrap During the
`Present Covid-19 Pandemic, signed April 20, 2020
`Samsung’s Preliminary Invalidity Contentions and Disclosures
`Pursuant To Patent Rules 3-3 and 3-4 (served November 9, 2020)
`Merriam-Webster Dictionary, online edition. Definition of
`“Halogen”, available at https://www.merriam-
`webster.com/dictionary/halogen (last visited Feb. 23, 2021)
`Illustrated Glossary of Organic Chemistry, UCLA. Illustration of
`Halide, available at
`http://www.chem.ucla.edu/~harding/IGOC/H/halide.html (last
`visitied Feb. 23, 2021)
`Mortvinova, N.E., Vinokurov, A.A., Lebedev, O.I., Kuznetsova,
`T.A., and Dorofeev, S.G., Addition of Zn during the phosphine-based
`synthesis of indium phosphide quantum dots:doping and surface
`passivation, Beilstein J Nanotechnol. 2015; 6: 1237-1246.
`Samsung’s Proposed Claim Constructions (served December 11,
`2020)
`
`vii
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`Exhibit
`2027
`
`2028
`2029
`
`2030
`2031
`2032
`
`2033
`
`2034
`
`2035
`2036
`
`2037
`
`2038
`
`2039
`
`2040
`
`Description
`He, Z., Yang, Y., Liu, J.W. and Yu, S.H., Emerging tellurium
`nanostructures: controllable synthesis and their
`applications. Chemical Society Reviews, 46(10): 2732-2753 (2017)
`INTENTIONALLY LEFT BLANK
`Makkar, M. and Viswanatha, R., Frontier challenges in doping
`quantum dots: synthesis and characterization. RSC
`Advances, 8(39):22103-22112 (2018).
`Declaration of Brandi Cossairt Ph.D. Aug. 12, 2021
`July 29, 2021 Deposition of Mark A. Green, Ph.D.
`Excerpts from June 10, 2021 Rebuttal Expert Report of Moungi
`Bawendi, Ph.D.
`Xie, L., et al., Characterization of Indium Phosphide Quantum Dot
`Growth Intermediates Using MALDI-TOF Mass Spectrometry.
`Journal of the American Chemical Society, 138:13469-13472 (2016).
`(Bawendi Depo. Exhibit 7)
`Excerpts from June 16, 2021 Deposition of Moungi G. Bawendi,
`Ph.D.
`Definition of Monodisperse by The Free Dictionary, Aug. 10, 2021
`Panfil, Y.E., Oded, M. and Banin, U., Colloidal quantum
`nanostructures: emerging materials for display
`applications. Angewandte Chemie International
`Edition, 57(16):4274-4295 (2018).
`MilliporeSigma, Solid State Synthesis, available at
`https://www.sigmaaldrich.com/US/en/applications/materials-science-
`and-engineering/solid-state-synthesis (last visited August 10, 2021).
`Fackler Jr, J.P., et al., Californium-252 plasma desorption mass
`spectrometry as a tool for studying very large clusters; evidence for
`vertex-sharing icosahedra as components of Au67 (PPh3)
`14Cl8. Journal of the American Chemical Society, 111(16):6434-
`6435 (1989).
`Xia, N., & Wu, Z., Controlling ultrasmall gold nanoparticles with
`atomic precision. Chemical Science, 12(7):2368-2380 (2021).
`Anderson, D.P., et al., Chemically synthesised atomically precise
`gold clusters deposited and activated on titania. Part II. Physical
`chemistry chemical physics, 15(35):14806-14813 (2013)
`
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`Exhibit
`2041
`
`2042
`
`2043
`2044
`
`2045
`
`2046
`
`Description
`Antoine, R., Atomically precise clusters of gold and silver: A new
`class of nonlinear optical nanomaterials. Frontier Research
`Today, 1:1001, 1-11 (2018)
`Shweky, I., Aharoni, A., Mokari, T., Rothenberg, E., Nadler, M.,
`Popov, I. and Banin, U., Seeded growth of InP and InAs quantum
`rods using indium acetate and myristic acid. Materials Science and
`Engineering: C, 26(5-7):788-794 (2006).
`PubChem – Cadmium Sulfide Compound Summary.
`New Electronics - Nanoparticles manufacturer receives $600,000
`boost, available at https://www.newelectronics.co.uk/electronics-
`news/nanoparticles-manufacturer-receives-600-000-boost/26831/
`(last visited August 10, 2021).
`Kangyong Kim, et al., Zinc Oxo Clusters Improve the Optoelectronic
`Properties on Indium Phosphide Quantum Dots, Chem. Mater. 2020,
`32, 2795-2802. (Bawendi Depo. Exhibit 8)
`Redacted Version of the Declaration of Dr. Brandi Cossairt, Aug. 12,
`2021
`
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
`
`I.
`
`INTRODUCTION AND SUMMARY OF ARGUMENT
`Samsung’s Petition fails to establish that any challenged claim of Nanoco’s
`
`U.S. Patent No. 8,524,365 (Ex. 1001) (the “’365 patent”) is unpatentable. The ’365
`
`patent claims are directed to semiconductor nanoparticles called quantum dots. The
`
`claimed semiconductor nanoparticles have a core semiconductor material disposed
`
`on a molecular cluster compound (“MCC”) where the core material contains
`
`elements that are not in the MCC. Ex. 1001, 20:9-13. As defined by the patent and
`
`construed by the District Court, a MCC is a small cluster of three or more metal
`
`atoms and their associated ligands of sufficiently well-defined chemical structure
`
`such that all molecules of the cluster compound possess the same relative molecular
`
`formula. Ex. 1091, 18. These “clusters are defined identical molecular entities, as
`
`compared to ensembles of small nanoparticles.” Ex. 1001, 7:48-53.
`
`Petitioner’s proposed Grounds 1-4 rely on a reference called Banin, which
`
`does not disclose a MCC. The “clusters” Petitioner identifies in Banin are melted
`
`gold droplets existing in a range of sizes with a 25% variation in their composition,
`
`and which contain substantial impurities. These metal droplets are uncharacterized
`
`mixtures of clusters. See Section VII.A infra. All experts in this proceeding, and in
`
`the parallel District Court proceeding, agree that uncharacterized mixtures of
`
`clusters fail to meet the definition of a MCC. During his deposition, Petitioner’s
`
`expert Dr. Green testified that such clusters do not meet the definition. See Ex. 2031,
`
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`68:6-14 (“Q. So if there was a mixture of clusters in your opinion, could that satisfy
`
`this definition [of MCC]? A. No, because they wouldn’t have the same relative
`
`molecular formula. Q. So in your opinion, would the molecular clusters have to be
`
`identical in order to satisfy this definition? A. I believe so.”). Petitioner’s expert in
`
`the District Court, Dr Bawendi, also testified that uncharacterized clusters that exist
`
`in a range of sizes are not MCCs. See Ex. 2034,
`
`
`
`
`
`
`
`
`
`show that any challenged claim is unpatentable at least because Banin does not
`
`) Petitioner’s Grounds 1-4 fail to
`
`disclose a MCC.
`
`Petitioner’s Ground 5 relies on Zaban as a primary reference in combination
`
`with Farneth and Yu. As the Board correctly noted, “Petitioner does not show
`
`sufficiently that an ordinarily skilled artisan would have replaced the zinc acetate in
`
`Zaban’s process with the Cd10S6Ph12 or Zn10S6Ph12 clusters disclosed Farneth. …
`
`Accordingly, Petitioner does not demonstrate a reasonable likelihood of prevailing
`
`at trial with respect to any challenged claim based on this ground.” Paper 17, 26.
`
`And Yu, has little to do with either Farneth or Zaban as it does not even disclose
`
`semiconductor particles at all. See Section VII.B infra.
`
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`The Petition’s Grounds 6 and 7 are weaker still. These Grounds combine
`
`Lucey with Ahrenkiel. As the Board noted “those disparate methods involve
`
`markedly different experimental conditions, reactants, and synthetic goals. … this
`
`ground appears to us to be based on impermissible hindsight reconstruction, rather
`
`than any suggestion, identified adequately by Petitioner, in the asserted prior art
`
`references.” Paper 17, 26-27.
`
`Because Petitioner’s grounds fail to disclose critical claim elements, and there
`
`is no reason to combine the cited references, Petitioner has not proven that any
`
`challenged claims of the ’365 patent are invalid.
`
`II. OVERVIEW OF QUANTUM DOT NANOPARTICLES
`The challenged claims are directed to semiconductor nanoparticles including
`
`quantum dots. Quantum dots are man-made semiconductors that can emit light at
`
`very particular wavelengths. They are tiny, ranging in size from 2-100 nanometers
`
`(nm), and it is their size that dictates the wavelength, and thus the color, of light
`
`being emitted—moving across the traditional visible spectrum from violet to red as
`
`the dots grow larger in diameter. Ex. 1001, 1:21-25; Ex. 2030 ¶34.
`
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`Ex. 2013, 1792. To achieve color precision, it is vital that all of the quantum dots in
`
`a particular batch are sufficiently uniform in size (i.e., “monodisperse quantum
`
`dots”). Monodisperse quantum dots are useful in televisions because of their fine-
`
`tunable color-generating properties. Ex. 2030 ¶35; see also Ex. 1001, 1:25-32. When
`
`such quantum dots are added to a film that sits in front of a television’s backlight,
`
`they reveal a wider and more saturated range of colors than would otherwise be
`
`possible. Ex. 2030 ¶35. Nanoco, an early pioneer in the manufacture of quantum
`
`dots, developed ways to manufacture monodisperse quantum dots in large quantities,
`
`and developed ways to make quantum dot films for use in displays.1 Id.
`
`1 In separate IPRs Samsung challenges Nanoco’s U.S. Patent Nos. 7,588,828,
`
`7,803,423, 7,867,557, and 9,680,068, which are also directed toward these
`
`inventions.
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`At the time of the invention, the most studied quantum dot material was
`
`cadmium selenide (CdSe). Ex. 2030 ¶36. This is because one can precisely control
`
`the size of CdSe quantum dots, and thus fine-tune the color they emit over the visible
`
`spectrum. Id.; Ex. 1001, 1:40-43. These CdSe quantum dots are made up of elements
`
`from columns 12 and 16 of the periodic table (also known as group II-VI quantum
`
`dots). Id.
`
`See Ex. 2004 (annotated).
`
`But cadmium is incredibly toxic and is banned from use in consumer
`
`electronics in many countries. Ex. 2030 ¶37. So a need arose for methods to make
`
`5
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`commercial amounts of cadmium-free quantum dots that could be fine-tuned to
`
`specific uniform sizes and color emissions across the visible spectrum. Id. Nanoco,
`
`in particular, focused its attention on the less toxic elements from columns 13 and
`
`15 of the period table (group III-V), such as indium phosphide (InP). Ex. 1001, 8:18-
`
`23. However, group III-V quantum dots are far more covalent in nature and more
`
`difficult and time consuming to prepare using prior art methods as a result. Ex. 1001,
`
`4:4-7; Ex. 2030 ¶ 38.
`
`Prior to Nanoco’s innovations, quantum dots made up of group III-V materials
`
`could not be produced in commercial quantities with the necessary size precision.
`
`See Ex. 1001, 3:54-4:32; Ex. 2030 ¶39. The existing commercial methods included
`
`taking a solution of precursors—i.e., chemicals that contribute, e.g., the indium
`
`and/or the phosphorus ions to an InP quantum dot core—and rapidly injecting them
`
`into a hot solvent. Id. This “hot injection” method worked well enough for small-
`
`scale productions of quantum dots, where the amounts of each solution were small
`
`enough that when the cool precursors were added, the entire solution immediately
`
`changed to the lower temperature. However, it did not work for larger scale
`
`productions because injecting large volumes of cool precursors into large volumes
`
`of hot solutions creates immediate temperature differentials throughout the solution.
`
`Id. These temperature differentials result in an undesirable assortment of quantum
`
`dots of different sizes. Ex. 1001, 4:53-56 (“For all the above methods rapid particle
`
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`Case No. IPR2021-00186
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`nucleation followed by slow particle growth is essential for a narrow particle size
`
`distribution.”); Ex. 2030 ¶39. As discussed above, a large range of size distribution
`
`defeats the purpose of quantum dots by eliminating the ability to fine-tune their
`
`optical properties.
`
`Nanoco solved the problem of nanoparticle size distribution by converting
`
`precursors (such as an indium-containing precursor and a phosphorus-containing
`
`precursor) into a quantum dot core (such as indium phosphide) in the presence of a
`
`MCC. Ex. 1001, 4:51-61, 5:5-9; Ex. 2030 ¶40. Nanoco’s “cluster assisted” growth
`
`methods enable the large-scale synthesis of high-quality, uniformly-sized, cadmium-
`
`free quantum dots. Ex. 1001, 5:9-19; Ex. 2030 ¶40.
`
`III.
`
`IDENTIFICATION OF INSTITUTED GROUNDS
`Petitioner alleges that the challenged claims of the ’365 patent are
`
`unpatentable on the following grounds:
`
`Ground
`
`Basis
`
`1
`
`2
`3
`4
`5
`6
`
`7
`
`35. U.S.C. §102
`
`35. U.S.C. §103
`35. U.S.C. §103
`35. U.S.C. §103
`35. U.S.C. §103
`35. U.S.C. §103
`
`35. U.S.C. §103
`
`Banin
`
`Reference(s)
`
`Challenged
`Claim
`1, 7-12, 17,
`22-23
`1, 7-12, 15-
`Banin
`17, 22-23
`Banin, Herron
`2-6, 18-21
`Banin, Treadway
`13, 14
`Zaban, Farneth, Yu
`1-9, 17-23
`1-2, 4, 7-12,
`17-18, 22-23 Lucey, Ahrenkiel
`Lucey, Ahrenkiel,
`13–16
`Treadway
`
`7
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`Case No. IPR2021-00186
`U.S. Patent No. 8,524,365
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`IV. OVERVIEW OF SEMICONDUCTOR NANOPARTICLE
`SYNTHESIS METHODS
`There are many different ways to manufacture many different kinds of
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`nanoparticles with many different characteristics. Petitioner mixes and matches
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`components from these various methods in its efforts to challenge the ’365 patent
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`claims. But each method has its own set of highly specific conditions, reagents, and
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`other conditions required to achieve highly specific objectives. Ex. 2030 ¶41. For
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`example, some reactions produce spherical nanoparticles (quantum dots). Id. ¶42.
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`Other reactions produce rod-shaped nanoparticles (nanorods). Id. Still others
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`produce quantum wires, ribbons, tubes, or sheets. Id.; Ex. 2031 (Green Dep.), 22:24–
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`24:13. Representative pictures of these differing structures are shown below:
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`See Ex. 2036, 4276.
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`Reaction conditions for producing nanoparticles vary widely. Some reactions
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`are performed at extremely high temperatures, while others can be carried out at
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`room temperature or with mild heat. Ex. 2030 ¶43. Some reactions use single-source
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`precursors (i.e., precursors that contain all of the atoms that go into the nanoparticle),
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`while others use multiple precursors each supplying a different atom to the growing
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`U.S. Patent No. 8,524,365
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`nanoparticle. Id. Some reactions use solid or vaporized precursors while others mix
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`the precursors in colloidal solutions (a colloid is a mixture in which particles remain
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`evenly distributed through the solution). Id. All of these different reactions have their
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`own particular set of requirements—and they are all targeted to obtaining a particular
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`set of characteristics in the resulting nanoparticle, such as the composition of the
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`nanoparticle, the quantity and purity desired, and so on. Id. ¶44.
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`Nanorods and Nanowires
`A.
`Nanorods and nanowires are elongated forms of semiconductor nanoparticles.
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`Ex. 2030 ¶45. To achieve their elongated shape, nanorods and nanowires grow in
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`one dimension. Id. Two common ways of achieving this one-dimensional growth
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`are (1) the Vapor-Liquid-Solid method, and (2) the Solution-Liquid-Solid method.
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`Id.
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`The Vapor-Liquid-Solid Method
`1.
`The Vapor-Liquid-Solid (“VLS”) method was first discovered when
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`researchers noticed that silicon (Si) “whiskers” would grow on gold (Au) decorated
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`silicon substrates when they were subjected to a process called chemical vapor
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`deposition (“CVD”). Ex. 2030 ¶46; see also Ex. 2008 (Solution-Liquid-Solid
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`Growth of Semiconductor Nanowires), 7513. For example, as its name suggests,
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`CVD uses a vaporized precursor to deposit silicon atoms directly onto a substrate.
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`Ex. 2030 ¶47. At the high temperatures required for this process, the metal catalyst
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`(e.g., gold) melts into variously sized droplets. Id.; see also Ex. 2008, 7513. In the
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`case of the silicon “whiskers,” the liquid gold droplets dissolve silicon atoms until
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`the droplets become supersaturated, at which point crystalline silicon nanorods (i.e.,
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`whiskers) begin forming at the interface of the gold droplet (the part of the droplet
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`that is touching the substrate). Ex. 2030 ¶48. Because the growing crystals form
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`where the droplet is already touching the silicon nanorod, they push the molten metal
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`droplet upwards as the elongated crystal forms below it. Growth like this in one
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`dimension creates rod-shaped nanoparticles. Id.; Ex. 2008 (Solution-Liquid-Solid
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`Growth of Semiconductor Nanowires), 7513. The “whiskers” will continue to grow
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`in this manner until the precursors are fully depleted. Id. The researchers who
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`discovered this process called it “VLS” in light of the three phases involved: Vapor-
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`phase (silicon precursors), Liquid phase (melted gold droplets, also called the
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`“catalyst”), and Solid phase (crystalline semiconductor whiskers). Id. A rendering
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`of the process is shown below:
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`Ex. 2008 (Wang 1), 7514.
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`While metals other than gold can be used in VLS, there are very particular
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`requirements that must be considered when choosing metals that will work. The
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`requirements include, but are not limited to:
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`(1)
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`the liquid metal (e.g., gold) must be able to dissolve the vaporized
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`substrate (e.g., silicon);
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`(2)
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`the solubility of the substrate must be low enough in the metal that
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`supersaturation can be achieved;
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`(3)
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`the vapor pressure of the catalyst over the liquid metal must be small
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`so that the droplet does not vaporize, shrink in volume (and therefore radius),
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`or decrease the radius of the growing wire until, ultimately, growth is
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`terminated;
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`(4)
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`the catalyst must be inert to the reaction products during nanowire
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`growth;
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`(5)
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`the vapor–solid, vapor–liquid, and liquid–solid interfacial energies
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`must be examined for compatibility before choosing a suitable catalyst.
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`Ex. 2030 ¶50; see also Ex. 2009, 422-427. When these conditions are met,
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`nanoparticle growth fueled by the supersaturated substrate occurs in the direction of
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`the catalyst.
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`Id., 423.
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`The Solution-Liquid-Solid Method
`2.
`The Solution-Liquid-Solid (“SLS”) method is related to VLS and also uses
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`molten metal catalysts to dissolve precursors and create one dimensional crystal
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`growth. Ex. 2030 ¶51. However, in contrast to VLS, SLS (1) is performed at lower
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`temperatures, (2) replaces the vapor precursor with a liquid precursor, and (3) takes
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`place in solution, meaning that the rods are not bound to a substrate. Id.; Ex. 2008,
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`7514. The SLS process is depicted below:
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`Id.
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`Similar to VLS, there are particular requirements that must be considered
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`when choosing metals catalysts to use in the SLS method. These include, but are not
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`Case No. IPR2021-00186
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`limited to the metal’s (1) melting point, (2) solvating ability, and (3) reactivity. Ex.
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`2030 ¶52; Ex. 2008, 7514. The melting point of the metal catalyst is an important
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`consideration because the SLS method only works if the metal first melts, before
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`dissolving precursors. See Ex. 2030 ¶53; Ex. 2007, 10889 (“The melting points,
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`semiconductor-component solubilities, and reactivities are important criteria for
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`judging candidate metals or metal alloys as potential SLS-catalyst materials.”); Ex.
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`2008, 7514 (“Catalyst particles must be molten under the reaction conditions.”).
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`Obviously, in SLS reactions the melting point of the metal catalyst must be lower
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`than the temperature at which the solution evaporates. Ex. 2030 ¶53; Ex. 2007,
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`10890 (noting that metal catalyst must “keep their melting points within the boiling
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`points of organic solvents.”). Therefore, SLS is typically performed somewhere
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`between ~200−350 °C because higher temperatures can cause the solvents to boil
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`away or become thermally unstable. Ex. 2008, 7514 (“Because we wished to use the
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`reaction temperature in the range of 200-300 °C, metal nanoparticles melting in that
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`range would be required.”). Thus, metal nanoparticles with low melting points have
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`been the most useful for the SLS growth of semiconductor materials under typical
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`reaction conditions. Ex. 2030 ¶53.
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`The solvating property of the metal catalyst is also an important consideration
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`in SLS reactions. See id. ¶52; Ex. 2007, 10889. The metal catalyst must be able to
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`dissolve at least one component of the semiconductor that is being made, yet have
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`such limited solubility that high supersaturation can occur and allow the
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`semiconductor material to precipitate out of the liquid metal catalyst and grow the
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`semiconductor crystal nanorod. Ex. 2030 ¶52; Ex. 2008, 7514-7515 (“at least one of
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`the components of the product semiconductor phase must have finite but limited
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`solubility in the catalyst material, so that high supersaturations can be achieved.”)
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`The reactivity of the liquid metal catalyst is another important consideration
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`when determining what metal catalyst to use in SLS reactions. See Ex. 2030 ¶52;
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`Ex. 2007, 10889. The metal catalyst should not react with or form a solid solution
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`with the target semiconductor unless the catalyst material is the same as one of the
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`constituent elements of the semiconductor. Ex. 2030 ¶52; Ex. 2008, 7515. Based
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`upon these considerations, indium (In), bismuth (Bi), and tin (Sn) are considered the
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`best metal catalysts for SLS growth of semiconductors, whereas in the early days of
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`SLS, gold (Au) was more commonly used. See Ex. 2008, 7515 (“The low melting
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`metals best meeting these [three] criteria seemed to be In, Bi, and Sn.”). Nanoco is
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`not aware of any SLS methods that employ semiconduct