Patent ID: 6951825

Claim:
A method of etching comprising: preparing a substrate; depositing a first etch stop layer taken from the group of materials consisting of Ti and TaN; forming an iridium bottom electrode layer; depositing a SiN layer; depositing and patterning an aluminum hard mask; etching a non-patterned SiN layer with a first etchant consisting of C 4 F 8 :Ar:O 2 =8:2:1, used at a microwave plasma power of between about 400 w to 600 w, and an RF power of between about 150 w to 250 w, stopping at the level of the iridium bottom electrode layer; etching first etch stop layer with a second etchant consisting of CF 4 : Ar:Cl=8:2:1, used at a microwave plasma power of between about 400 w to 600 w, and an RF power of between about 150 w to 250 w; depositing an oxide layer and CMP the oxide layer to the level of the remaining SiN layer; wet etching the SiN layer to form a trench; depositing a layer of ferroelectric material in the trench formed by removal of the SiN layer; depositing a layer of high-k oxide; and completing the device, including metallization.