A fabrication method for microstructures with high aspect ratios uses a CMOS process to form a desired microstructure on a silicon substrate. The steps of forming a contact plug and a via plug of the process are used to form etching channels in insulation layers, polysilicon layers and metal layers, penetrating to the silicon substrate. An etching process is then performed through the etching channel to form the desired microstructure with high aspect ratio.
The method includes chemical-mechanical polishing to planarize an insulating interlayer deposited on a lower pattern. The insulating interlayer is polished using a surfactant. The chemical-mechanical polishing includes at least two separate polishing steps of different fluxes of the surfactant. The first polishing step is performed for touching up an upper side of the insulating layer. The second polishing step is performed, after completing the first polishing step, for planarizing the insulating interlayer.
