Novel chemical mechanical polishing (CMP) process using a fixed abrasive tool (FX-tool), which is a kind of grindstone, was developed for dielectric planarization. In order to obtain flat surface for 45-nm-node of semiconductor generation, two points that are adopting stiff polishing pad/tool and reducing concentration of free-abrasives become critical issues. Newly developed FX-tool has more than ten times higher Young's modulus than that of a conventional CMP pad, and simultaneously, concentration of free abrasives on its surface can be controlled by polishing time. In experiments using several test-wafers, less than 30nm of dishing was obtained up to 3mm-length-pattern. Additionally, polyacrylic ammonium (PAA) effectively affects to increase degree of selectivity between oxide and nitride for shallow trench isolation (STI) process. The selectivity of 41 was obtained at 3 vol.% concentration of PAA. STI test wafers were successfully polished without any additional processes such as etching back.