ruthenium layer 31 and penetrating silicon nitride substrate 11 the appearance of the structure is now as shown in fig4 with arrow 42 pointing to the region of separation between two individual bottom electrodes now moving to fig5 all remaining photoresist has been removed at this point a second reactive ion etching process is initiated in this case the etchant used is one of several possible gaseous compounds of carbon oxygen and hydrogen such as ch 3 oh co nh 3 c 2 h 5 oh etc with ch 3 oh being preferred no additional photoresist is required instead the previously etched layer 12 acts as a hard mask during the etching of layers 31 and 10 etching of all exposed ruthenium surfaces now proceeds at a rate of about 8 nm min until silicon nitride layer 11 is exposed at which point the second reactive ion etching process may be terminated also u201c at leisure u201d with no danger of penetrating silicon nitride substrate 11 by more than about 60 angstroms the appearance of the structure is now as shown in fig5 referring now to fig6 the process of the 2 nd embodiment starts with sputter cleaning of the.