Method of fabricating a coronary-type capacitor in an integrated circuit

Abstract

A method of fabricating a coronary-type capacitor in integrated circuit is provided, which method helps increase the capacitance of the capacitor by forming the electrode of the capacitor with a coronary-like shape that is relatively large in surface area. In this method, a stacked structure of doped polysilicon layers and HSG polysilcon layers are formed in an alternating manner, which is then selectively removed to form a void portion. A heat-treatment process is then performed on the wafer at a temperature of about 600-700° C. to cause the impurity ions in the doped polysilicon layers to be activated and evenly diffused over the inside of the doped polysilicon layers. Finally, a selective etching process is performed with an etchant that can react with polysilicon at a faster etching rate than with HSG polysilcon so as to cause the sidewalls of the doped polysilicon layers to be more recessed than the sidewalls of the HSG polysilcon layers. The remaining portions of the doped polysilicon layers and the HSG polysilcon layers in combination constitute a coronary-shaped electrode structure that serves as the bottom electrode of the capacitor.