Current thermal analysis tools can only efficiently handle 3D integrated circuits with simple structure.To deal with more complicated stacked 3D integrated circuits

more complex

and error-prone boundary conditions need to be set up.In this paper

we propose simple

yet efficient method

called minimal boundary method

to handle the complicated boundary conditions by transforming the 3D stacked structure to a structure with simple boundary (thus for easy boundary condition set up).To boost the thermal analysis via iterative conjugate gradient method

we construct a novel preconditioner

which consists of the thermal conductor matrices of the building blocks of the stacked 3D structure as its diagonal blocks.Experimental results show that by using finite element method along with the proposed minimal boundary pre-processing

we can obtain accurate thermal analysis results.The proposed preconditioner can reduce the 90% iterations in the conjugate gradient method.