An interactive two-dimensional model for designing VLSI CCD's

An interactive two-dimensional (2-D) program has been developed for CCD design. Device structures are designed using a graphics terminal, and the corresponding 2-D potentials are obtained by solving Poisson's equation. The potentials are then used to calculate the density of mobile charges, employing the 2-D charge-integration method developed in this work. The accuracy and the limit of this approximation are established by comparing this method with 2-D simulations based on simultaneous solutions of Poisson's and current-continuity equations. Using this model, we have calculated charge-transfer efficiencies as a function of CCD channel width for different strengths of fat zeros. The calculated results agree fairly well with device measurements.