DT capacitor with silicide outer electrode and/or compressive stress layer, and related methods
Method of forming a deep trench capacitor are provided. The method may include forming a deep trench in a substrate; enlarging a width of a lower portion of the deep trench to be wider than a width of the rest of the deep trench; epitaxially forming a compressive stress layer in the lower portion of the deep trench; forming a metal-insulator-metal (MIM) stack within the lower portion of the deep trench; and filling a remaining portion of the deep trench with a semiconductor. Alternatively to forming the compressive stress layer or in addition thereto, a silicide may be formed by co-deposition of a refractory metal and silicon.
1. A method of forming a deep trench capacitor, the method comprising:
forming a deep trench in a substrate;
enlarging a width of a lower portion of the deep trench to be wider than a width of the rest of the deep trench;
epitaxially forming a compressive stress layer only in the lower portion of the deep trench;
forming a metal-insulator-metal (MIM) stack within the lower portion of the deep trench, wherein an outer metal layer of the metal-insulator-metal (MIM) stack contacts the compressive stress layer; and
filling a remaining portion of the deep trench with a semiconductor.
2. The method of claim 1 , wherein enlarging the width of the lower portion includes, while protecting an upper portion of the deep trench by depositing an etch resistant layer on top thereof, performing a wet etch of the lower portion to remove a portion thereof.
3. The method of claim 1 , wherein forming the MIM stack includes co-depositing a refractory metal and silicon into the lower portion of the deep trench to form an outer electrode.
4. The method of claim 3 , wherein the co-depositing includes alternating depositing of the refractory metal and the silicon.
5. The method of claim 3 , wherein the co-depositing further includes controlling an amount of the silicon deposited to control a tensile stress of the outer electrode formed thereby.
6. The method of claim 3 , wherein the MIM stack forming further includes forming a node dielectric layer and an inner electrode layer in the lower portion of the deep trench over the outer electrode.
7. The method of claim 6 , wherein the node dielectric is chosen from the group consisting of: silicon oxide (SiO 2 ), silicon nitride (Si 3 4 ), silicon oxynitride (SiON), tantalum oxide (Ta 2 O 5 ), barium-titanium oxide (BaTiO 3 ), hafnium oxide (HfO 2 ), zirconium oxide (Zr 0 2 ), aluminum oxide (Al 2 0 3 ), hafnium silicon oxide (HfSiO).
8. The method of claim 6 , wherein the inner electrode layer includes epitaxial polysilicon germanium (epi polySiGe).
9. The method of claim 8 , further comprising doping the polysilicon germanium with an n-type dopant.
10. The method of claim 1 , wherein the compressive stress layer forming includes epitaxially growing silicon germanium on a surface of the lower portion of the deep trench.
11. The method of claim 10 , further comprising doping the silicon germanium with an n-type dopant.