Patents by Inventor Tapas K. Das

Tapas K. Das 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 for multiresolution analysis assisted reinforcement learning approach to run-by-run control
    Patent number: 7672739
    Abstract: A new multiresolution analysis (wavelet) assisted reinforcement learning (RL) based control strategy that can effectively deal with both multiscale disturbances in processes and the lack of process models. The application of wavelet aided RL based controller represents a paradigm shift in the control of large scale stochastic dynamic systems of which the control problem is a subset. The control strategy is termed a WRL-RbR controller. The WRL-RbR controller is tested on a multiple-input-multiple-output (MIMO) Chemical Mechanical Planarization (CMP) process of wafer fabrication for which process model is available. Results show that the RL controller outperforms EWMA based controllers for low autocorrelation. The new controller also performs quite well for strongly autocorrelated processes for which the EWMA controllers are known to fail. Convergence analysis of the new breed of WRL-RbR controller is presented.
    Type: Grant
    Filed: August 11, 2006
    Date of Patent: March 2, 2010
    Assignee: University of South Florida
    Inventors: Rajesh Ganesan, Tapas K. Das, Kandethody M. Ramachandran
  • Fortified authentication on multiple computers using collaborative agents
    Patent number: 7617523
    Abstract: Authentication mechanisms for accessing one or more applications by a user by using collaborative agents for automating authentication to the one or more applications. The use of collaborative agents obviates a need for the user to remember fortified authentication credentials for each application.
    Type: Grant
    Filed: October 21, 2005
    Date of Patent: November 10, 2009
    Assignee: International Business Machines Corporation
    Inventors: Tapas K. Das, Nitin Sharma, Jingxue Shen
  • System and method for the identification of chemical mechanical planarization defects
    Patent number: 7377170
    Abstract: The present invention presents a novel application of a wavelet-based multiscale method in a nanomachining process chemical mechanical planarization (CMP) of wafer fabrication. The invention involves identification of delamination defects of low-k dielectric layers by analyzing the nonstationary acoustic emission (AE) signal collected during copper damascene (Cu-low k) CMP processes. An offline strategy and a moving window-based strategy for online implementation of the wavelet monitoring approach are developed.
    Type: Grant
    Filed: October 31, 2006
    Date of Patent: May 27, 2008
    Assignee: University of South Florida
    Inventors: Rajesh Ganesan, Tapas K. Das, Arun K. Sikder, Ashok Kumar