Patents by Inventor Alfred S. Hou

Alfred S. Hou 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).

  • System and method for high-speed potentiometry using scanning probe microscope
    Patent number: 5488305
    Abstract: A potentiometry apparatus for measuring a periodic electrical waveform existing proximate the surface of a sample such as a semiconductor wafer is disclosed herein. The potentiometry apparatus includes a pulse generator for generating a sequence of electrical pulses at a pulse frequency offset from the frequency of the surface waveform by a mixing frequency. A cantilever coupled to the pulse generator serves to carry the electrical pulses to a position proximate the surface of the sample. In a capacitive displacement mode the cantilever is mechanically displaced so as to generate a time-expanded representation of the electrical surface waveform having a repetition frequency equal to the mixing frequency. During displacement mode operation an optical detection circuit may be employed to monitor deflection of the cantilever. In a tunneling current mode the cantilever is again employed to carry the electrical pulses to a position proximate the surface of the sample.
    Type: Grant
    Filed: September 28, 1994
    Date of Patent: January 30, 1996
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: David M. Bloom, Francis Ho, Alfred S. Hou
  • System and method of measuring high-speed electrical waveforms using force microscopy and offset sampling frequencies
    Patent number: 5381101
    Abstract: A potentiometry apparatus for measuring a periodic electrical waveform existing proximate the surface of a sample such as a semiconductor wafer is disclosed herein. The potentiometry apparatus includes a pulse generator for generating a sequence of electrical pulses at a pulse frequency offset from the frequency of the surface waveform by a mixing frequency. A cantilever coupled to the pulse generator serves to carry the electrical pulses to a position proximate the surface of the sample. In a capacitive displacement mode the cantilever is mechanically displaced so as to generate a time-expanded representation of the electrical surface waveform having a repetition frequency equal to the mixing frequency. During displacement mode operation an optical detection circuit may be employed to monitor deflection of the cantilever. In a tunneling current mode the cantilever is again employed to carry the electrical pulses to a position proximate the surface of the sample.
    Type: Grant
    Filed: December 2, 1992
    Date of Patent: January 10, 1995
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: David M. Bloom, Francis Ho, Alfred S. Hou