Abstract: The thermal mechanical reliability of low resistivity silicon through silicon via (LRS-TSV) and copper-filled TSV was analyzed and compared based on finite element method (FEM). The results show that, the protrusion area of LRS-TSV emerges mainly upon polymer insulation and the aluminum layer above the silicon pillar, the height is 82 nm and 76 nm respectively. The protrusion area of copper-filled TSV emerges mainly upon the copper layer above the copper pillar, the maximum value is 150 nm. The largest stress of the LRS-TSV emerges on both sides of the polymer insulation layer, the maximum value can reach up to 1 005 MPa. And the largest stress of Copper-filled TSV emerges on the outside of the central copper pillar, the maximum value is 1 227 MPa. In addition, the largest interfacial stress of the two types of TSV structure all appears at both ends near the TSV. The stress of the LRS-TSV can not exceed 400 MPa, while the stress of copper-filled TSV can exceed 800 MPa. Based on the above results, it is concluded that the LRS-TSV possesses higher thermal mechanical reliability than the copper-filled TSV.