Patents by Inventor Nelson N. Tam

Nelson N. Tam 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: 5700602
    Abstract: A metrology pattern on a reticle comprising a phase-shifted feature and an additional phase-shifted feature and/or non phase-shifted feature is disclosed. The metrology pattern can be used to determine the target thickness for achieving 180.degree. phase difference, i.e., zero phase error on a phase-shifted reticle. A test reticle having several such metrology patterns, with several different phase-shifter thickness differences is used to produce a CD versus defocus data for each of the phase-shifter thickness differences by performing an exposure matrix or series of aerial images. The data can be used to determine a target thickness for zero phase error. The data can also be used to determine a correlation between focal shift, phase error, and shifter thickness. The metrology pattern can be placed on reticles used for the fabrication of semiconductor devices, for example, so that an exposure matrix can be performed, to determine any focal shift, which can then be related to phase error.
    Type: Grant
    Filed: October 30, 1995
    Date of Patent: December 23, 1997
    Assignee: Intel Corporation
    Inventors: Giang T. Dao, Nelson N. Tam, Gang Liu, Jeffrey N. Farnsworth
  • Patent number: 5384219
    Abstract: A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and method of fabricating the reticle. Each of the patterns and inverted patterns are structurally identical with regard to the direction of phase shift, so that any focal shift due to phase error is in the same direction for all patterns. In a preferred embodiment, the structurally identical inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist.
    Type: Grant
    Filed: August 31, 1993
    Date of Patent: January 24, 1995
    Assignee: Intel Corporation
    Inventors: Giang T. Dao, Qi De Qian, Nelson N. Tam, Eng T. Gaw, Harry H. Fujimoto
  • Patent number: 5348826
    Abstract: A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and methods of fabricating the reticle. Each of the patterns and inverted patterns are structurally identical with regard to the direction of phase shift, so that any focal shift due to phase error is in the same direction for all patterns. In a preferred embodiment, the structurally identical inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist.
    Type: Grant
    Filed: February 2, 1993
    Date of Patent: September 20, 1994
    Assignee: Intel Corporation
    Inventors: Giang T. Dao, Qi De Qian, Nelson N. Tam, Eng T. Gaw, Harry H. Fujimoto
  • Patent number: 5300379
    Abstract: A phase-shifted reticle with patterns proximate each other having inverted phases for the features and phase-shifting elements, and methods of fabricating the reticle, are disclosed. In a preferred embodiment, the inverted reticle is used to form an array of closely spaced contact or via openings. For a first pattern on the reticle, the feature will be the 0.degree. phase and the phase-shifting rim surrounding that feature will be the 180.degree. phase. All patterns surrounding the first pattern have phase-shifting rims of the 0.degree. phase and features of the 180.degree. phase. In this way, each pattern can form below conventional resolution features in the resist. Additionally, there will not be exposure of the regions between the closely spaced features since radiation transmitted through the closely spaced phase-shifting rims of the two patterns is 180.degree. out of phase.
    Type: Grant
    Filed: August 21, 1992
    Date of Patent: April 5, 1994
    Assignee: Intel Corporation
    Inventors: Giang T. Dao, Eng T. Gaw, Nelson N. Tam, Ruben A. Rodriquez