Plasma etching of lead germanate (PGO) ferroelectric thin film

The lead germanate (PGO) thin film has been proposed for FeRAM devices, esp ecially for one transistor ferroelectric memory cell application. To realiz e such applications, it is important not only to form the PGO thin film, bu t also to etch/pattern such thin film. In this work, plasma etching of PGO thin films was investigated by using chlorine or fluorine gas chemistries i n an electron cyclotron resonance plasma reactor. Etch rates were studied a s a function of etching conditions. The results indicated that a chemical e ffect, rather than a pure physical sputtering, was the dominant factor duri ng the plasma etching of PGO material. It was also found that under the sam e etching conditions, a Cl-2/Ar chemistry was more effective in PGO etching than a CF4/Ar chemistry. Under the etching conditions studied, there was n o obvious plasma etching damage to the composition of the PGO thin films. H owever, the surface oxygen and chlorine concentration increased after the e tching, indicating there might be some etch-induced surface residue. Such r esidue was thermally unstable, and can be greatly reduced by a postetch ann eal in O-2. (C) 2001 American Vacuum Society.