Patents by Inventor David R. McDonald

David R. McDonald has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6337032
    Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.
    Type: Grant
    Filed: February 16, 2000
    Date of Patent: January 8, 2002
    Assignees: Nortel Networks Limited, Queen's University
    Inventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
  • Patent number: 6066581
    Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: May 23, 2000
    Assignees: Nortel Networks Corporation, Queen's University
    Inventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
  • Patent number: 5728603
    Abstract: A method is provided for forming a crystalline perovskite phase of a ferroelectric dielectric material by a process of depositing a layer of amorphous ferroelectric precursor material and then annealing in an oxygen containing atmosphere in the presence of water vapor, preferably with the addition of a few percent of ozone and at a temperature of less than 500.degree. C. Advantageously, the method provides for formation of a ferroelectric material comprising lead zirconate titanate, with low film stress, high dielectric constant and low leakage current. The reduced thermal budget allows for increase flexibility in integration of ferroelectric materials, e.g. after a step of deposition of low melting point metal or metal alloy.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: March 17, 1998
    Assignee: Northern Telecom Limited
    Inventors: Ismail T. Emesh, David R. McDonald, Vsanta Chivukula
  • Patent number: 5358889
    Abstract: A method is provided for forming a conductive layer of ruthenium oxide layer RuO.sub.2. The RuO.sub.2 layer is formed from a coating of a precursor solution comprising a ruthenium (III) nitrosyl salt,subsequent heat treatment, and annealing at low temperature. The resulting layer of a tetragonal phase of crystalline ruthenium oxide is suitable for formation thereon of a perovskite structure ferroelectric material for applications in ferroelectric non-volatile memory cells. The chloride free process is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS integrated circuits.
    Type: Grant
    Filed: April 29, 1993
    Date of Patent: October 25, 1994
    Assignee: Northern Telecom Limited
    Inventors: Ismail T. Emesh, David R. McDonald