A 3-D general-purpose device simulator is presented, and issues related to its geometrical flexibility and computational efficiency are discussed. Triangular-based prismatic elements are used as building blocks for the discretization of device equations, providing a reasonable tradeoff between simplicity and geometrical flexibility. Suitable numerical techniques, including a 'local-solution' algorithm, have been implemented in order to improve the computational efficiency of the code. A general treatment has been devised to handle floating-gate devices, which allows the program to cope with complex structures, such as a dual EPROM structure. Three-dimensional and two-dimensional simulation results are compared.>

An algorithm allowing the automatic generation of a mesh and accounting for the main physical features of the problem is presented. The adaptivity is provided by a refinement strategy which preserves the characteristics of the initial grid, inserting nodes only in the regions where the solution deviates from a linear behavior. A geometrical interpretation in terms of a monitor surface is given, and various different approaches to the problem are discussed. The efficiency of the algorithm is enhanced by a local solution scheme, which uses previously computed values of all the unknown quantities as boundary conditions for the newly generated nodes. A few examples illustrate the performance of the algorithm.>