Convolution based compact thermal model for 3D-ICs: Methodology and accuracy analysis

Thermal analysis is essential in 3D-IC technology due to the reduced footprint and higher power densities compared to conventional 2D packaging [1]. Compact thermal models (CTM) are being developed for fast evaluation of the thermal distribution in the 3D packages. The CTM discussed in this paper is based on the Green´s function theory and exploits convolution and fast Fourier transform to compute the temperature profiles starting from matrices storing the power dissipation densities (power maps) and the temperature responses to hot spots. Detailed accuracy assessments are presented for the grid size and for the number of images to be considered for an accurate modelling of the lateral insulating boundary conditions. A two dies stack case study is also analysed showing good agreement with the finite element model results (error less than 0.5%). Finally, the algorithm computational time is discussed indicating a O(N logN) behaviour where N is the number of elements in the matrices.