Patents by Inventor Thomas Warren Lassiter

Thomas Warren Lassiter 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: 10319899
    Abstract: A microelectronic device containing a piezoelectric thin film element is formed by oxidizing a top surface of a piezoelectric layer with an oxygen plasma, and subsequently forming an etch mask containing photoresist on the oxidized top surface. The etch mask is conditioned with an oven bake followed by a UV bake. The piezoelectric layer is etched using a three step process: a first step includes a wet etch of an aqueous solution of about 5% NH4F, about 1.2% HF, and about 18% HCl, maintaining a ratio of the HCl to the HF of about 15.0, which removes a majority of the piezoelectric layer. A second step includes an agitated rinse. A third step includes a short etch in the aqueous solution of NH4F, HF, and HCl.
    Type: Grant
    Filed: August 4, 2017
    Date of Patent: June 11, 2019
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Neng Jiang, Xin Li, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, YungShan Chang
  • Patent number: 9939710
    Abstract: A method includes placing a device having a titanium nitride layer into a chamber. The device also has a mask that includes a photoresist material and an aluminum copper hardmask. The method also includes performing an ashing process on the mask using the chamber. The method further includes, after the ashing process, performing an etching process using the chamber to etch through portions of the titanium nitride layer. Performing the etching process includes flowing a gas mixture containing tetrafluoromethane (CF4) and oxygen gas (O2) into the chamber at a temperature of at least about 200° C.
    Type: Grant
    Filed: June 24, 2016
    Date of Patent: April 10, 2018
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Neng Jiang, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, Nayeemuddin Mohammed, YungShan Chang
  • Publication number: 20170338401
    Abstract: A microelectronic device containing a piezoelectric thin film element is formed by oxidizing a top surface of a piezoelectric layer with an oxygen plasma, and subsequently forming an etch mask containing photoresist on the oxidized top surface. The etch mask is conditioned with an oven bake followed by a UV bake. The piezoelectric layer is etched using a three step process: a first step includes a wet etch of an aqueous solution of about 5% NH4F, about 1.2% HF, and about 18% HCl, maintaining a ratio of the HCl to the HF of about 15.0, which removes a majority of the piezoelectric layer. A second step includes an agitated rinse. A third step includes a short etch in the aqueous solution of NH4F, HF, and HCl.
    Type: Application
    Filed: August 4, 2017
    Publication date: November 23, 2017
    Inventors: Neng Jiang, Xin Li, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, YungShan Chang
  • Patent number: 9755139
    Abstract: A microelectronic device containing a piezoelectric thin film element is formed by oxidizing a top surface of a piezoelectric layer with an oxygen plasma, and subsequently forming an etch mask containing photoresist on the oxidized top surface. The etch mask is conditioned with an oven bake followed by a UV bake. The piezoelectric layer is etched using a three step process: a first step includes a wet etch of an aqueous solution of about 5% NH4F, about 1.2% HF, and about 18% HCl, maintaining a ratio of the HCl to the HF of about 15.0, which removes a majority of the piezoelectric layer. A second step includes an agitated rinse. A third step includes a short etch in the aqueous solution of NH4F, HF, and HCl.
    Type: Grant
    Filed: June 13, 2015
    Date of Patent: September 5, 2017
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Neng Jiang, Xin Li, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, YungShan Chang
  • Publication number: 20160313627
    Abstract: A method includes placing a device having a titanium nitride layer into a chamber. The device also has a mask that includes a photoresist material and an aluminum copper hardmask. The method also includes performing an ashing process on the mask using the chamber. The method further includes, after the ashing process, performing an etching process using the chamber to etch through portions of the titanium nitride layer. Performing the etching process includes flowing a gas mixture containing tetrafluoromethane (CF4) and oxygen gas (O2) into the chamber at a temperature of at least about 200° C.
    Type: Application
    Filed: June 24, 2016
    Publication date: October 27, 2016
    Inventors: Neng Jiang, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, Nayeemuddin Mohammed, YungShan Chang
  • Patent number: 9405089
    Abstract: A method includes placing a device having a titanium nitride layer into a chamber. The device also has a mask that includes a photoresist material and an aluminum copper hardmask. The method also includes performing an ashing process on the mask using the chamber. The method further includes, after the ashing process, performing an etching process using the chamber to etch through portions of the titanium nitride layer. Performing the etching process includes flowing a gas mixture containing tetrafluoromethane (CF4) and oxygen gas (O2) into the chamber at a temperature of at least about 200° C.
    Type: Grant
    Filed: November 5, 2014
    Date of Patent: August 2, 2016
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Neng Jiang, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, Nayeemuddin Mohammed, YungShan Chang
  • Patent number: 9304283
    Abstract: An apparatus includes first and second electrodes separated by an insulative material (such as a piezoelectric material). The apparatus also includes a protective layer over the first and second electrodes. The protective layer has a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode. The apparatus further includes a first electrical contact at least partially within the first opening and electrically coupled to the first electrode. In addition, the apparatus includes a second electrical contact at least partially within the second opening and electrically coupled to the second electrode. Each of the first and second electrical contacts includes a stack of metal layers. The stack of metal layers includes a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.
    Type: Grant
    Filed: November 5, 2014
    Date of Patent: April 5, 2016
    Assignee: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Joel Soman, Neng Jiang, Scott Summerfelt, Thomas Warren Lassiter, Nayeemuddin Mohammed, Mary Alyssa Drummond Roby
  • Publication number: 20150380637
    Abstract: A microelectronic device containing a piezoelectric thin film element is formed by oxidizing a top surface of a piezoelectric layer with an oxygen plasma, and subsequently forming an etch mask containing photoresist on the oxidized top surface. The etch mask is conditioned with an oven bake followed by a UV bake. The piezoelectric layer is etched using a three step process: a first step includes a wet etch of an aqueous solution of about 5% NH4F, about 1.2% HF, and about 18% HCl, maintaining a ratio of the HCl to the HF of about 15.0, which removes a majority of the piezoelectric layer. A second step includes an agitated rinse. A third step includes a short etch in the aqueous solution of NH4F, HF, and HCl.
    Type: Application
    Filed: June 13, 2015
    Publication date: December 31, 2015
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Neng Jiang, Xin Li, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, YungShan Chang
  • Publication number: 20150338604
    Abstract: An apparatus includes first and second electrodes separated by an insulative material (such as a piezoelectric material). The apparatus also includes a protective layer over the first and second electrodes. The protective layer has a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode. The apparatus further includes a first electrical contact at least partially within the first opening and electrically coupled to the first electrode. In addition, the apparatus includes a second electrical contact at least partially within the second opening and electrically coupled to the second electrode. Each of the first and second electrical contacts includes a stack of metal layers. The stack of metal layers includes a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.
    Type: Application
    Filed: November 5, 2014
    Publication date: November 26, 2015
    Inventors: Joel Soman, Neng Jiang, Scott Summerfelt, Thomas Warren Lassiter, Nayeemuddin Mohammed, Mary Alyssa Drummond Roby
  • Publication number: 20150340245
    Abstract: A method includes placing a device having a titanium nitride layer into a chamber. The device also has a mask that includes a photoresist material and an aluminum copper hardmask. The method also includes performing an ashing process on the mask using the chamber. The method further includes, after the ashing process, performing an etching process using the chamber to etch through portions of the titanium nitride layer. Performing the etching process includes flowing a gas mixture containing tetrafluoromethane (CF4) and oxygen gas (O2) into the chamber at a temperature of at least about 200° C.
    Type: Application
    Filed: November 5, 2014
    Publication date: November 26, 2015
    Inventors: Neng Jiang, Joel Soman, Thomas Warren Lassiter, Mary Alyssa Drummond Roby, Nayeemuddin Mohammed, YungShan Chang