Method for preparing a lead-free piezoelectric thin film

{
  "publication_number": "US9450175B2",
  "country": "US",
  "kind": "B2",
  "title": "Method for preparing a lead-free piezoelectric thin film",
  "abstract": "The present invention discloses a method of preparing a lead-free piezoelectric thin film comprising the steps of: providing a precursor solution comprising at least one alkali metal ion, a polyamino carboxylic acid, and an amine; depositing the precursor solution on a substrate to form a film; and annealing the film. The present invention also provides a lead-free piezoelectric thin film prepared according to the method, a precursor solution for use in the method and a method of preparing the precursor solution.",
  "claims": [
    "1. A method for preparing a lead-free piezoelectric thin film comprising: providing a precursor solution for use in preparing a lead-free piezoelectric thin film comprising: at least one alkali metal ion; a polyamino carboxylic acid; and an alkanolamine; depositing the precursor solution on a substrate to form a film; and annealing the film.",
    "2. The method according to claim 1, wherein the method further comprises decomposing the film by heating prior annealing.",
    "3. The method according to claim 2, wherein depositing and decomposing are repeated at least once prior to annealing.",
    "4. The method according to claim 1, wherein annealing comprises heating the film at a temperature of about 580-700° C.",
    "5. The method according to claim 1, wherein the lead-free piezoelectric thin film has a formula (K 0.5 Na 0.5)NbO 3.",
    "6. The method according to claim 1, further comprising depositing a solution comprising lithium ions on the film after annealing.",
    "7. The method according to claim 6, wherein the method comprises heating the film after depositing a solution comprising lithium ions and subsequently annealing the film for a second time.",
    "8. The method according to claim 7, wherein the film has a formula of 0.06LiNbO 3 -0.94(K 0.5 Na 0.5)NbO 3."
  ],
  "description_excerpt": "The present invention relates to a method for preparing a lead-free piezoelectric thin film. The present invention also relates to a lead-free piezoelectric thin film obtained from the method.\n\nLead-based piezoelectric materials have been widely used in sensors, actuators, transducers, and many other electronic devices. The increasing applications of these devices generate a more aggravated environmental concern because these traditional lead-based piezoelectric ceramics typically contain more than 60% lead by weight. Intensive efforts have been made to develop lead-free piezoelectric materials to replace the lead-based compositions. Potassium sodium niobate (Group IA-VB) system is one of the most promising candidates as a lead-free piezoelectric ceramic material. Potassium sodium niobate, (K,Na)NbO 3 (KNN) based ceramics have a broad operation temperature range due to high Curie temperature of about ˜420° C., and large piezoelectric coefficient in the bulk ceramic.\n\nFor the applications in various microelectronics and micro electromechanical devices and systems (MEMS), lead-free piezoelectric thin films instead of bulk ceramics are demanded. However, it is highly challenging to obtain KNN-based piezoelectric thin films with excellent piezoelectric performance properties. The piezoelectric coefficient for KNN thin films is typically far below the expected value as compared to the bulk counterparts. The effective du values for the KNN thin and thick films from a chemical solution deposition method are in the range of 40 to 61 pm/V.",
  "cpc": [
    "H01L 41/318",
    "C01G 33/00",
    "C01G 33/006",
    "C01P 2002/50",
    "C01P 2002/72",
    "C01P 2002/89",
    "C01P 2006/32",
    "C01P 2006/40",
    "C04B 2235/3201",
    "C04B 2235/3203",
    "C04B 2235/3255",
    "C04B 2235/44",
    "C04B 2235/441",
    "C04B 2235/449",
    "C04B 35/495",
    "C04B 35/6264",
    "C04B 35/632",
    "C04B 35/63444",
    "C04B 35/63488",
    "H01L 41/0805",
    "H01L 41/1873",
    "H10N 30/078",
    "H10N 30/704",
    "H10N 30/8542"
  ],
  "ipc": [
    "H10N 30/00",
    "H10N 30/078",
    "H10N 30/85",
    "H10N 30/853",
    "C01G 33/00",
    "C04B 35/495",
    "C04B 35/626",
    "C04B 35/632",
    "C04B 35/634"
  ],
  "assignees": [
    "Agency for Science Technology and Research Singapore"
  ],
  "inventors": [
    "Phoi Chin Goh",
    "Kui Yao"
  ],
  "filing_date": "2015-01-22",
  "publication_date": "2016-09-20",
  "grant_date": "2016-09-20",
  "priority_date": "2010-05-20",
  "application_number": "US-201514603265-A",
  "family_id": "44991930",
  "cited_by_count": 1,
  "citations": [
    "US3330697A",
    "US5900223A",
    "JP2001127354A",
    "US6306204B1",
    "US20070024162A1",
    "US20080308762A1",
    "WO2010115493A2",
    "US20120091389A1",
    "US20130064970A1"
  ]
}