Low dielectric constant materials are now required as intermetallic dielectrics to reduce RC delay in advanced technologies. Hydrogen silsesquioxane (HSQ) is a spin-on dielectric with a dielectric constant around 3. Local planarization of HSQ and its impact on the global planarization due to CMP process was studied. Local planarization of HSQ and its impact on the global planarization due to CMP process was studied. When lines and spaces are equal, HSQ shows a good planarization for lines smaller than 20 μm. In this case, the HSQ thickness on metal line is equal to 2500 Å, which is the minimum which can be obtained for this metal thickness and HSQ deposited. For various environments of the metal line HSQ planarizes better for small lines in a dense zone created by an array of lines or plates of metal. For the CMP process the planarization is good for small lines, as for HSQ but in an array of lines only. Plates must be totally prohibited for CMP process. Finally, for an intermetal dielectric including HSQ the goal of CMP is no more a local planarization as for gap fill but a large scale intra-die planarization.