Methods for forming low resistivity contacts

A method for reducing contact resistance, comprising:

• performing a selective titanium silicide (TiSi) deposition process on a middle-of-the-line (MOL) contact structure including a cavity in a substrate of dielectric material with a silicon-based connection portion at a bottom of the cavity, wherein the selective TiSi deposition process is selective to silicon-based material over dielectric material and a TiSi layer of approximately 3 nm to approximately 6 nm is formed on the silicon-based connection portion;
• performing a selective deposition process of fluorine free tungsten on the MOL contact structure in-situ, wherein the selective deposition process is selective to TiSi material over dielectric material and forms a silicide capping layer on the silicon-based connection portion;
• performing a seed layer deposition process of tungsten on the contact structure, wherein tungsten deposited on the contact structure is approximately 2 nm to approximately 3 nm in thickness;
• performing a selective etch process to remove portions of tungsten deposited by the seed layer deposition process on sidewalls of the cavity of the MOL contact structure while maintaining tungsten on the bottom of the contact structure and on the silicon-based connection portion;
• and
• depositing a tungsten gapfill material in a bottom-up selective deposition process to fill the MOL contact structure.

A non-transitory, computer readable medium having instructions stored thereon that, when executed, cause a method for decreasing contact resistance to be performed, the method comprising:

• performing a selective titanium silicide (TiSi) deposition process on a middle-of-the-line (MOL) contact structure including a cavity in a substrate of dielectric material with a silicon or silicon germanium connection portion at a bottom of the cavity, wherein the selective TiSi deposition process is selective to silicon or silicon germanium material over dielectric material and a TiSi layer of approximately 3 nm to approximately 6 nm is formed on the silicon or silicon germanium connection portion;
• performing a selective deposition process of fluorine free tungsten on the MOL contact structure in-situ, wherein the selective deposition process is selective to TiSi material over dielectric material and forms a silicide capping layer on the silicon or silicon germanium connection portion;
• performing a seed layer deposition process of tungsten on the contact structure, wherein tungsten deposited on the contact structure is approximately 2 nm to approximately 3 nm in thickness;
• performing a selective etch process to remove portions of tungsten deposited by the seed layer deposition process on sidewalls of the cavity of the MOL contact structure while maintaining tungsten on the bottom of the contact structure and on the silicon or silicon germanium connection portion;
• and
• depositing a tungsten gapfill material in a bottom-up selective deposition process to fill the MOL contact structure.