Novel Storage-Node Contacts with Stacked Point-Cusp Magnetron Sp-TiN Barrier for Metal–Insulator–Metal Ru/Ta 2 O 5 /Ru Capacitors in Gigabit Dynamic Random Access Memories

We have investigated a mechanism for increasing the contact resistance ( R c ) of the ruthenium (Ru) and the titanium nitride (TiN) barrier during the tantalum oxide (Ta 2 O 5 ) oxidation annealing in the metal–insulator–metal (MIM) capacitors. It has been found that controlling the atomic ratio of Ti to N (Ti/N ratio) is a key to keeping the contact resistance low. Controlling the Ti/N ratio is easy for the sp-TiN, while it is difficult for the chemical-vapor-deposited TiN. On the basis of this result, we have proposed a novel Ru/TiN contact with a stacked-barrier structure fabricated by using the point-cusp magnetron (PCM) sputtering method. We have applied this structure to the MIM-Ru/Ta 2 O 5 /Ru capacitor in a gigabit DRAM with 0.10 µm design. In this capacitor, we have obtained the contact resistance of 10 kΩ·bit and the capacitor leakage current of 10 -17 A/bit in the range of -1 to +1 V.