Abstract: This paper focuses on thermal mechanical analysis of low resistivity silicon through silicon via (LRS-TSV), since there are few researches on it. Firstly, the process flow for LRS-TSV based interposer was introduced. Then based on experimental dimension of LRS-TSV, protrusion height and thermal stress of LRS-TSV were simulated under 350℃. The simulation result shows that, compared with copper based TSV, protrusion area of LRS-TSV are mainly upon polymer insulation. To decrease protrusion height and thermal stress of LRS-TSV, factors such as process temperature, thickness of top SiO₂ layer, LRS-TSV diameter, height, space and thickness of insulation were investigated respectively. From results, it shows that decreasing the thickness and height of insulation, increasing thickness of top SiO₂ layer are effective solutions to reduce the protrusion height and release thermal stress.