Browsing by Author "Guo, SF"

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Accurate calculation of collision integrals using adaptive methods
(1997-02-01)
Gau, YT
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this work, we have developed accurate and efficient methods for calculating the scattering angle, time integral and electronic energy loss for binary collisions in matter. In contrast to the conventional integration and the hard sphere approximations, our new time integral is obtained by calculating the difference between the distance to the target atom and the ion path length. To compute the scattering angle and time integral accurately and efficiently, an adaptive Simpson quadrature using a smoother integrand is adopted. The energy loss arising from the local electron-concentration-dependent electronic stopping power is obtained by tracing the ion trajectory. To reduce the computation time, a second-order differential equation for the ion motion using an adaptive Runge-Kutta-Fehlberg algorithm is developed.
New techniques for simulation of ion implantation by numerical integration of Boltzmann transport equation
(1998-01-01)
Wang, SW
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
New techniques for more accurate and efficient simulation of ion implantations by a stepwise numerical integration of the Boltzmann transport equation (BTE) have been developed in this work. Instead of using uniform energy grid, a non-uniform grid is employed to construct the momentum distribution matrix. A more accurate simulation result is obtained for heavy ions implanted into silicon. In the same time, rather than utilizing the conventional Lindhard, Nielsen and Schoitt (LNS) approximation, an exact evaluation of the integrals involving the nuclear differential scattering cross-section (d sigma(n) = 2 pi p dp) is proposed. The impact parameter p as a function of ion energy E and scattering angle phi is obtained by solving the magic formula iteratively and an interpolation techniques is devised during the simulation process. The simulation time using exact evaluation is about 3.5 times faster than that using the Littmark and Ziegler (LZ) spline fitted cross-section function for phosphorus implantation into silicon.
New techniques for simulation of ion implantation by numerical integration of Boltzmann transport equation
(1998-01-01)
Wang, SW
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
New techniques for more accurate and efficient simulation of ion implantations by a stepwise numerical integration of the Boltzmann transport equation (BTE) have been developed in this work. Instead of using uniform energy grid, a non-uniform grid is employed to construct the momentum distribution matrix. A more accurate simulation result is obtained for heavy ions implanted into silicon. In the same time, rather than utilizing the conventional Lindhard, Nielsen and Schoitt (LNS) approximation, an exact evaluation of the integrals involving the nuclear differential scattering cross-section (d sigma(n) = 2 pi p dp) is proposed. The impact parameter p as a function of ion energy E and scattering angle phi is obtained by solving the magic formula iteratively and an interpolation techniques is devised during the simulation process. The simulation time using exact evaluation is about 3.5 times faster than that using the Littmark and Ziegler (LZ) spline fitted cross-section function for phosphorus implantation into silicon.
Parallel simulation of ion implantation for multi-component targets using Boltzmann transport equation
(1998-07-01)
Wang, SW
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A stepwise Boltzmann transport equation (BTE) simulation using non-uniform energy grid momentum matrix and exact nuclear scattering cross-section is successfully parallelized.to simulate the ion implantation of multi-component targets. Assuming that the interactions of ion with different target atoms are independent, the scattering of ions with different components can be calculated concurrently by different processors. It is developed on CONVEX SPP-1000 and the software environment of parallel virtual machine (PVM) with a master-slave paradigm. A speedup of 3.3 has been obtained for the simulation of As ions implanted into AZ1350 (C6.2H6O1N0.15S0.06) which is composed of five components. In addition, our new scheme gives better agreement with the experimental results for heavy ion implantation than the conventional method using a uniform energy grid and approximated scattering function.
Rational function approximation of nuclear scattering cross-section function
(1996-12-01)
Wang, SS
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The one-variable scattering cross-section function f(eta) proposed by Lindhard, Nielsen and Scharff (LNS) is approximated by a rational function using the minimax algorithm in this work. Taking an ingenious transformation ion of the variable eta, this approximation is about one order of magnitude faster than other approximations in the literature. To maintain a reasonable accuracy, we divide the wide variable range into two regions. In addition, an adaptive integration method is adopted to compute the scattering angle and the nuclear stopping power in order to get accurate f(eta) data.
Rational function approximation of nuclear scattering cross-section function
(1996-12-01)
Wang, SS
;
Guo, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The one-variable scattering cross-section function f(eta) proposed by Lindhard, Nielsen and Scharff (LNS) is approximated by a rational function using the minimax algorithm in this work. Taking an ingenious transformation ion of the variable eta, this approximation is about one order of magnitude faster than other approximations in the literature. To maintain a reasonable accuracy, we divide the wide variable range into two regions. In addition, an adaptive integration method is adopted to compute the scattering angle and the nuclear stopping power in order to get accurate f(eta) data.