Low resistance contact structures including a copper fill for trench structures
View Patent ↗An electrical device is provided that includes at least one contact surface and an interlevel dielectric layer present atop the electrical device. The interlevel dielectric layer may include at least one trench to the at least one contact surface of the electrical device. A liner of tantalum or tantalum nitride can be present on sidewalls of the trench structure and a base surface of the trench provided by the contact surface of the electrical device. A copper fill promoting liner that includes at least one ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), molybdenum (Mo), and copper (Cu) may be in direct contact with the liner of tantalum or tantalum nitride. A copper containing metal that fills the at least one trench and is present directly on the copper fill promoting liner.
1. A method of forming a contact to an electrical device comprising:
forming a titanium liner composed entirely of titanium (Ti) in direct contact with sidewalls of at least one trench structure and a base surface of the at least one trench structure corresponding to a contact surface of the electrical device, the at least one trench structure being formed through dielectric material to a surface of a source or drain region, wherein the Ti of the titanium liner provides a metal element for siliciding the contact surface;
forming a liner of tantalum or tantalum nitride on the titanium liner, including depositing the liner of tantalum or tantalum nitride using a physical vapor deposition method to protect the Ti for the siliciding;
forming a copper fill promoting liner comprising ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), molybdenum (Mo), copper (Cu), or a combination on the liner of tantalum or tantalum nitride; and
forming a copper containing metal that fills the at least one trench structure.
2. The method of claim 1 , wherein the titanium liner comprises a thickness ranging from 10 Å to 100 Å.
3. The method of claim 1 , wherein forming the liner of tantalum or tantalum nitride further comprises employing at least one process selected from the group consisting of: plating, electroplating, electroless plating, and sputtering.
4. The method of claim 1 , wherein the liner of tantalum or tantalum nitride has a thickness ranging from 10 Å to 50 Å.
5. The method of claim 1 , wherein forming the copper fill promoting liner further comprises employing at least one process selected from the group consisting of: physical vapor deposition and chemical vapor deposition.
6. The method of claim 1 , wherein forming the copper fill promoting liner further comprises employing at least one deposition process selected from the group consisting of: plating, electroplating, electroless plating, and sputtering.
7. The method of claim 1 , wherein the copper fill promoting liner has a thickness ranging from 10 Å to 50 Å.
8. The method of claim 1 , wherein the copper containing metal comprises 100 wt. % copper.
9. The method of claim 1 , wherein forming the copper containing metal further comprises employing at least one deposition process selected from the group consisting of: plating, electroplating, electroless plating, sputtering, and copper reflow processing.
10. The method of claim 1 , further comprising:
siliciding the contact surface by subjecting the titanium liner to an anneal process to form a metal semiconductor alloy with a semiconductor material.