Nonconvex Hamiltonians in three dimensional level set simulations of the wet etching of silicon

It is shown that profile evolution during anisotropic wet etching of silicon can be described by the nonconvex Hamiltonian arising in the Hamilton-Jacobi equation for the level set function. Etching rate function is determined on the basis of the silicon symmetry properties. An extension of the sparse field method for solving three dimensional level set equations in the case of nonconvex Hamiltonians is presented.