A 2-D semi-analytical model of parasitic capacitances for MOSFETs in ultra short channel, which takes the presence of high k gate dielectric into account, is developed. By using a semi-analytical method and an eigenfunction expansion method, we obtain part of expressions about capacitances. The model provides a good calculation method for parasitic capacitances and matches well with simulation results. It can be used in circuit simulation and device design directly. (C) 2013 Elsevier Ltd. All rights reserved.