OXYGEN PLASMA SURFACE TREATMENT OF (111) IRIDIUM FOR LITHOGRAPHY PROCESSING
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-12
For embedded dynamic random access memory (EmDRAM) devices, Iridium (Ir) has been found to be a good electrode material for DRAM capacitors, in conjunction with high dielectrics materials such as barium strontium titanate (BST). However, we have found that photoresist can not be stripped using downstream oxygen plasma etching when the resist is in direct contact with Ir. It is suspected that Ir is such a strong catalyst that it catalyzes a cross link- ing chemical reaction at the resist / Ir interface and hardens the resist during the subsequent high tem- perature processes, resulting in the inability to strip the resist using the aforementioned oxygen plasma process. After ashing, residue with same resist pat- tern was observed optically on Ir surface and was characterized by AFM and cross section SEM at about ZOOOA in thickness, Organic and ionic conta- minants were detected by TOF-SIMS analysis of the Ir surface prior to the resist coating without O2 plas- ma treatment. This may relate to the formation of the residue after ashing. A 0, plasma pre-treatment of Ir surface is shown to clean and passivate the Ir surface resulting in the easy removal of resist during the ashing process.