Method of forming lower electrode of capacitor using dry etching of platinum group metal film

摘要

A method of forming a lower electrode of a capacitor by a method of etching a platinum group metal film using a mixed gas of Ar, O ₂ and halogen gas is disclosed. In the present invention, a barrier layer formed of any one selected from the group consisting of TiN, TiSiN, TiAlN or TaSiN is formed on the semiconductor substrate including a conductive plug connected to an active region of the semiconductor substrate. A conductive layer selected from the group consisting of Pt, Ir, IrO ₂ , Ru, and RuO ₂ is formed on the barrier layer. A hard mask including Ti or TiN and partially exposing the conductive layer is formed on the conductive layer. Using the hard mask as an etch mask, dry etching the exposed conductive layer using a ternary gas mixture containing Ar, O ₂ , and Cl ₂ to partially expose the barrier layer and conduct the conductive layer under the hard mask. Form a layer pattern. The hard mask is removed by dry etching the hard mask and the exposed barrier layer using a binary gas mixture containing O ₂ and fluorine. The ternary gas mixture comprises at least 70 volume% O ₂ , 3 to 15 volume% Cl ₂ and 3 to 15 volume% Ar based on the volume of the ternary gas mixture. The binary gas mixture comprises at least 60 to 95 volume percent O ₂ based on the volume of the binary gas mixture.