Patents by Inventor Alexander F. Liu

Alexander F. Liu 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: 11823883
    Abstract: An ion detector for secondary ion mass spectrometer, the detector having an electron emission plate coupled to a first electrical potential and configured to emit electrons upon incidence on ions; a scintillator coupled to a second electrical potential, different from the first electrical potential, the scintillator having a front side facing the electron emission plate and a backside, the scintillator configured to emit photons from the backside upon incidence of electrons on the front side; a lightguide coupled to the backside of the scintillator and confining flow of photons emitted from the backside of the scintillator; and a solid-state photomultiplier coupled to the light guide and having an output configured to output electrical signal corresponding to incidence of photons from the lightguide. A SIMS system includes a plurality of such detectors movable arranged over the focal plane of a mass analyzer.
    Type: Grant
    Filed: November 19, 2021
    Date of Patent: November 21, 2023
    Assignee: NOVA MEASURING INSTRUMENTS, INC.
    Inventors: Christopher F. Bevis, Yungman Alan Liu, David Allen Reed, Eli Cheifetz, Amit Weingarten, Alexander Kadyshevitch
  • Patent number: 6190927
    Abstract: An improved method for specifying and reliably detecting endpoints in processes such as plasma etching, where the signal-to-noise ratio has been severely degraded due to factors such as “cloudy window” and low ratio of reactive surface area to non-reactive surface area. The improved method of the invention samples signals produced by photo sensitive equipment, digitally filters and cross-correlates the data, normalizes the data using an average normalization value, and provides further noise reduction through the use of three modes of endpoint specification and detection. The three modes of endpoint specification and detection require a pre-specified number of consecutive samples to exhibit a certain behavior before the endpoint is deemed detected and the process terminated as a result. The three modes of endpoint specification and detection also permit a very fine control of the etch time by permitting the user to adjust the specified endpoint by gradations of the sampling period.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: February 20, 2001
    Assignee: Lam Research Corporation
    Inventor: Alexander F. Liu
  • Patent number: 5738756
    Abstract: An improved method for specifying and reliably detecting endpoints in processes such as plasma etching, where the signal-to-noise ratio has been severely degraded due to factors such as "cloudy window" and low ratio of reactive surface area to non-reactive surface area. The improved method of the invention samples signals produced by photo sensitive equipment, digitally filters and cross-correlates the data, normalizes the data using an average normalization value, and provides further noise reduction through the use of three modes of endpoint specification and detection. The three modes of endpoint specification and detection require a pre-specified number of consecutive samples to exhibit a certain behavior before the endpoint is deemed detected and the process terminated as a result. The three modes of endpoint specification and detection also permit a very fine control of the etch time by permitting the user to adjust the specified endpoint by gradations of the sampling period.
    Type: Grant
    Filed: June 30, 1995
    Date of Patent: April 14, 1998
    Assignee: Lam Research Corporation
    Inventor: Alexander F. Liu
  • Patent number: 3938091
    Abstract: A customer code word issuing machine is provided wherein a customer manually inputs to the machine his secret password. The machine encodes the password and displays his corresponding issued code word. A verification machine is provided which includes a dial or keyboard for manually inputting the customer's password and the issued code word. The verification machine encodes the inputted password to derive an output for comparison with the manually inputted code word to derive an output indicative of the truth or falseness of the match of the code word with the respective password. The verification machine may be employed to open a lock, to allow use of a credit card for a telephone call, purchase of goods, etc.
    Type: Grant
    Filed: July 19, 1974
    Date of Patent: February 10, 1976
    Assignee: Atalla Technovations Company
    Inventors: Martin M. Atalla, Alexander F. Liu