Patents by Inventor Deven M. Raj

Deven M. Raj 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: 8728587
    Abstract: A plasma processing apparatus and method are disclosed which improve the repeatability of various plasma processes. The actual implanted dose is a function of implant conditions, as well as various other parameters. This method used knowledge of current implant conditions, as well as information about historical data to improve repeatability. In one embodiment, a plasma is created, a first sensing system is used to monitor a composition of the plasma and a second sensing system is used to monitor a total number of ions implanted. Information about plasma composition and dose per pulse is used to control one or more operating parameters in the plasma chamber. In another embodiment, this information is combined with historical data to control one or more operating parameters in the plasma chamber. In another embodiment, the thickness of material on the walls is measured, and used to modify one or more operating parameters.
    Type: Grant
    Filed: June 24, 2011
    Date of Patent: May 20, 2014
    Assignee: Varian Semiconductor Equipment Associates, Inc.
    Inventors: George Papasouliotis, Deven M. Raj, Harold Persing
  • Patent number: 7586100
    Abstract: A method of controlling a plasma doping process using a time-of-flight ion detector includes generating a plasma comprising dopant ions in a plasma chamber proximate to a platen supporting a substrate. The platen is biased with a bias voltage waveform having a negative potential that attracts ions in the plasma to the substrate for plasma doping. A spectrum of ions present in the plasma is measured as a function of ion mass with a time-of-flight ion detector. The total number ions impacting the substrate is measured with a Faraday dosimetry system. An implant profile is determined from the measured spectrum of ions. An integrated dose is determined from the measured total number of ions and the calculated implant profile. At least one plasma doping parameter is modified in response to the calculated integrated dose.
    Type: Grant
    Filed: February 12, 2008
    Date of Patent: September 8, 2009
    Assignee: Varian Semiconductor Equipment Associates, Inc.
    Inventors: Deven M. Raj, Ludovic Godet, Bernard Lindsay, Timothy Miller, George Papasouliotis
  • Publication number: 20090200461
    Abstract: A method of controlling a plasma doping process using a time-of-flight ion detector includes generating a plasma comprising dopant ions in a plasma chamber proximate to a platen supporting a substrate. The platen is biased with a bias voltage waveform having a negative potential that attracts ions in the plasma to the substrate for plasma doping. A spectrum of ions present in the plasma is measured as a function of ion mass with a time-of-flight ion detector. The total number ions impacting the substrate is measured with a Faraday dosimetry system. An implant profile is determined from the measured spectrum of ions. An integrated dose is determined from the measured total number of ions and the calculated implant profile. At least one plasma doping parameter is modified in response to the calculated integrated dose.
    Type: Application
    Filed: February 12, 2008
    Publication date: August 13, 2009
    Applicant: VARIAN SEMICONDUCTOR EQUIPMENT ASSOCIATES, INC.
    Inventors: Deven M. Raj, Ludovic Godet, Bernard Lindsay, Timothy Miller, George D. Papasouliotis
  • Publication number: 20090084987
    Abstract: A plasma processing apparatus includes a process chamber, a source configured to generate a plasma in the process chamber, and a platen configured to support a workpiece in the process chamber. The platen is biased with a pulsed platen signal having pulse ON and OFF time periods to accelerate ions from the plasma towards the workpiece during the pulse ON time periods and not the pulse OFF time periods. A plate is positioned in the process chamber. The plate is biased with a plate signal to accelerate ions from the plasma towards the plate to cause an emission of secondary electrons from the plate during at least a portion of one of the pulse OFF time periods of the pulsed platen signal to at least partially neutralize charge accumulation on the workpiece.
    Type: Application
    Filed: September 28, 2007
    Publication date: April 2, 2009
    Applicant: VARIAN SEMICONDUCTOR EQUIPMENT ASSOCIATES, INC.
    Inventors: Ludovic GODET, Svetlana RADOVANOV, George D. PAPASOULIOTIS, Deven M. RAJ, Vikram SINGH, Timothy J. MILLER, Ziwei FANG