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METHOD FOR PRODUCING FERROELECTRIC FILM, FERROELECTRIC FILM, AND USAGE THEREOF

Foreign code F210010277
File No. (S2019-0399-N0)
Posted date 2021年1月27日
Country 世界知的所有権機関(WIPO)
International application number 2020JP018031
International publication number WO 2020218617
Date of international filing 令和2年4月27日(2020.4.27)
Date of international publication 令和2年10月29日(2020.10.29)
Priority data
  • 特願2019-086836 (2019.4.26) JP
  • 特願2019-086840 (2019.4.26) JP
Title METHOD FOR PRODUCING FERROELECTRIC FILM, FERROELECTRIC FILM, AND USAGE THEREOF
Abstract Provided are a method for forming a ferroelectric film of a metal oxide having a fluorite structure at a temperature lower than 300˚C and a ferroelectric film obtained at a low temperature. The present invention provides a method for producing a ferroelectric film containing a crystalline metal oxide having an orthorhombic phase fluorite structure by sputtering a target by a sputtering method while the temperature of a substrate is less than 300˚C so as to deposit a film of a metal oxide capable of forming an orthorhombic phase fluorite structure on the substrate, and ensuring that the thermal history of the resulting film is less than 300˚C or applying an electric field to the film after the deposition or after the thermal history. In addition, the present invention also provides the above ferroelectric film formed on an organic substrate, glass, or metal substrate intended only for low-temperature use, and a ferroelectric element, ferroelectric functional element, or device using the ferroelectric film.
Outline of related art and contending technology BACKGROUND ART
Conventionally, barium titanate BaTiO3 , lead zirconate Pb (Zr , Ti) O3 , (Pb , La) (Zr , Ti) O3 , BiFeO3 and the like have been known as ferroelectric materials. Ferroelectric substance is a kind of dielectric substance, in which electric dipoles are aligned and the direction of the dipoles can be changed by electric field even if there is no electric field outside. Since the ferroelectric substance is a dielectric substance having not only ferroelectricity but also pyroelectricity and piezoelectricity, it is also utilized as a capacitor, electro-optical element, memory element, transistor, pyroelectric element, piezoelectric element, etc. The ferroelectric piezoelectric material is a material in which polarization proportional to pressure appears when pressure is applied to the material, and on the other hand, the material is deformed when an electric field is applied. Piezoelectric bodies are widely used as piezoelectric elements in igniters, sonars, speakers, and the like.
(Non-Patent Document 1,2, etc.), in which ferroelectric properties have been reported in a film using a HfO2-based solid solution material which is a metal oxide having a fluorite type structure of a rectangular crystal phase. To solve the problem that a conventional ferroelectric material is a composite oxide having a perovskite group structure and has a large number of constituent elements of (4 or more and), a large fluctuation in composition and crystal structure, a toxic constituent element is included, a high vapor pressure is included, and composition control is difficult by volatilization is difficult, and the like, and ZrO2 , Since the HfO2-based solid solution material has a fluorite structure and is a simple oxide, the number of constituent elements is small, fluctuation of composition and crystal structure is small, reproducibility is excellent, it is not necessary to use a material toxic to constituent elements, and it is possible to form a film.
As a method for forming the inorganic ferroelectric film, a sputtering method, a sol-gel method, a CVD (Chemical Vapor Deposition) method, PLD (Pulsed Laser Deposition) Method, ALD (Atomic Layer Deposition) Method, hydrothermal synthesis, and the like are known (, for example, Patent Document 1 and Patent Document 2). Of these known methods, an inorganic ferroelectric film cannot be obtained unless deposition is performed at a high temperature of 300 °C. or higher, or annealing is performed at a high temperature of 300 °C. or higher after deposition. Therefore, in addition to the problems of productivity and cost, there is a drawback in that heat resistance is required for a substrate that can be used, and an organic substrate or the like cannot be used. On the other hand, the hydrothermal synthesis method can obtain an inorganic ferroelectric substance at a temperature of 300 °C. or lower, but has problems in that it cannot be used depending on applications because of wet process.
  • Applicant
  • ※All designated countries except for US in the data before July 2012
  • TOKYO INSTITUTE OF TECHNOLOGY
  • Inventor
  • FUNAKUBO, Hiroshi
  • SHIMIZU, Takao
  • MIMURA, Takanori
  • NAKAMURA, Yoshiko
  • SHIMURA, Reijiro
  • TASHIRO, Yu-ki
IPC(International Patent Classification)
Specified countries National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DJ DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS JO JP KE KG KH KN KP KR KW KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN WS ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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