Patents by Inventor Ken Edward Tokunaga

Ken Edward Tokunaga 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).

  • Dynamic feedback electrostatic wafer chuck
    Patent number: 5812361
    Abstract: An electrostatic chuck system having an electrostatic chuck for securely holding a wafer on a surface of the electrostatic chuck. The electrostatic chuck system comprises a wafer bias sensor coupled to a first portion of the electrostatic chuck for sensing an alternating current signal at the first portion. The wafer bias sensor outputs, responsive to the alternating current signal, a direct current voltage level representative of a direct current bias level of the wafer. The electrostatic chuck system further comprises a variable electrostatic chuck power supply coupled to the wafer bias sensor. The variable electrostatic chuck power supply provides a first potential level to the first portion of the electrostatic chuck.
    Type: Grant
    Filed: March 29, 1996
    Date of Patent: September 22, 1998
    Assignee: Lam Research Corporation
    Inventors: Phillip Lawrence Jones, Seyed Jafar Jafarian-Tehrani, Boris V. Atlas, David R-Chen Liu, Ken Edward Tokunaga, Ching-Hwa Chen