Liner to form composite high-K dielectric
Provided are methods to reduce the thickness of a high-κ layer needed in a DRAM capacitor and, thus, allow the cell electrodes to be larger, giving higher cell capacitance. A tantalum nitride (TaN) layer is introduced as a liner in the capacitor hole before a titanium nitride (TiN) electrode layer. The TaN layer converts to a thin layer of tantalum oxide (Ta 2 O 5 ), which permits a reduction in the high-κ layer thickness for the same capacitance versus leakage. Because this Ta 2 O 5 is formed directly on the cell electrode, it ensures a low leakage film exists in the narrowest gaps even before the high-κ layer is deposited.
1 . A capacitor of a memory device comprising:
a bottom electrode comprising a pillar of electrode material;
a metal nitride liner directly on the bottom electrode, the metal nitride liner comprising one or more of tantalum nitride (TaN), yttrium nitride (YN), zirconium nitride (ZrN), hafnium nitride (HfN), lanthanum nitride (LaN), and barium nitride (BaN);
an oxide layer directly on the metal nitride liner, oxide layer comprising one or more of tantalum oxide (Ta 2 O 5 ), yttrium oxide (YO), zirconium oxide (ZrO 2 ), hafnium oxide (HfO 2 ), lanthanum oxide (La 2 O 3 ), and barium oxide (BaO);
a high-κ dielectric layer directly on the oxide layer, the high-κ dielectric layer having a thickness in a range of from about 3 nm to about 6.5 nm; and
a top electrode on the high-κ dielectric layer.
2 . The capacitor of claim 1 , wherein the metal nitride liner consists essentially of tantalum nitride (TaN).
3 . The capacitor of claim 1 , wherein the metal nitride liner has a thickness in a range of from about 1 nm to about 4 nm.
4 . The capacitor of claim 1 , wherein the oxide layer consists essentially of tantalum oxide (Ta 2 O 5 ).
5 . The capacitor of claim 1 , wherein the oxide layer has a thickness in a range of from greater than 0 nm to about 1 nm.
6 . The capacitor of claim 1 , wherein the high-κ dielectric layer comprises one or more of hafnium oxide (HfO 2 ), zirconium oxide (ZrO 2 ), vanadium oxide (VO 2 ), titanium oxide (TiO 2 ), aluminum oxide (Al 2 O 3 ), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), niobium oxide (Nb 2 O 5 ), or lanthanum oxide (LaO).
7 . The capacitor of claim 6 , wherein the high-κ dielectric layer consists essentially of zirconium oxide (ZrO) and aluminum oxide (Al 2 O 3 ).
8 . The capacitor of claim 1 , wherein the bottom electrode and the top electrode independently comprise titanium nitride (TiN).