METHOD FOR FORMING CAPACITOR

摘要

PURPOSE: A method for forming a capacitor is provided to reduce a cusp of the sidewall of a cylindrical lower electrode, by using a phosphosilicate glass(PSG) layer to form a spacer and by etching polysilicon for the sidewall wherein a ratio of an anisotropic etch rate to an isotropic etch rate is from 2:1 to 3:1. CONSTITUTION: A lower region of the cylindrical lower electrode where the first insulation layer is stacked is formed on a semiconductor substrate(21). Polysilicon and the second insulation layer are sequentially formed on the entire surface including the lower region. The second insulation layer spacer is etched to form an insulation layer spacer on the sidewall of the lower region including the polysilicon. The polysilicon is selectively etched to form a cylindrical upper region connected to the lower region. The insulation layer spacer and the first insulation layer are eliminated to expose the cylindrical lower region and upper region. Roughness is formed on the surface of the exposed lower region and upper region.