FinFET Contact Manufacturing via Tri-Layer Mask and Oxide Cap
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Solution Overview
Problem
The existing FinFET manufacturing process faces challenges in accurately controlling the critical dimensions of vertical contacts M0A in both X and Y directions due to top rounding caused by excessive titanium nitride (TiN) consumption, leading to divergent line widths and poor line width roughness, which affects the performance and reliability of semiconductor devices.
Innovation Solution
A manufacturing method involving a non-rounded TiN profile for FinFET contacts is developed, utilizing a tri-layer mask and an oxide protective cap to prevent TiN consumption during etching, ensuring precise control of critical dimensions by maintaining the oxide cap height between 50-100 angstroms and using a conductive material to lead out the active area to the wire layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing dry etching process is used to manufacture vertical contact M0A, then the contact can be formed, but top rounding occurs due to excessive TiN consumption leading to bad line width roughness
Solution Approach 1:
The patent applies preliminary action by forming an oxide protective cap on the metal hard mask before the etching process. This oxide cap prevents excessive TiN consumption during etching, thereby avoiding top rounding and maintaining good line width roughness control in the vertical contact M0A.
Solution Approach 2:
The oxide protective cap serves as an intermediary layer between the metal hard mask and the etching environment. It mediates the etching process by protecting the TiN layer from excessive consumption while allowing the etching to proceed, thus resolving the contradiction between forming the contact and maintaining precision.
2Ease of manufacture
If metal hard mask and self-alignment technology (CMD) are adopted in 14 nm FinFET, then better manufacture capability is achieved, but process control becomes tough
Solution Approach 1:
The patent segments the manufacturing process into distinct steps with clearly defined masks and protective layers. The tri-layer mask structure and oxide protective cap divide the complex CMD process into manageable segments, making process control easier while maintaining manufacture capability.
Solution Approach 2:
The oxide protective cap provides local quality protection only where needed (on the metal hard mask), allowing different regions of the structure to have different protection levels. This enables precise control of the etching process while maintaining the benefits of metal hard mask technology.
3Manufacturing precision
If tri-layer mask and oxide protective cap are used to prevent TiN consumption, then critical dimensions are accurately controlled, but device complexity increases
Solution Approach 1:
The oxide protective cap is formed as a preliminary layer before etching, enabling accurate critical dimension control from the outset. This preliminary protection prevents the need for complex corrective measures later in the process, balancing the added step with overall process simplification.
Data Source
AI summary
The present disclosure relates to a FinFET and a manufacturing method of a contact. The manufacturing method comprises steps of: sequentially generating an interlayer dielectric layer, a metal hard mask, an oxide protective cap and a tri-layer mask on a gate to form a device to be etched; photoetching the tri-layer mask to remove photoresist in a non-patterned area; performing main etch on the device to be etched after the photoetching to remove the interlayer dielectric layer in the area that is not covered by the metal hard mask, and the metal hard mask is provided with the oxide protective cap; performing ODL removal on the device to be etched after the main etch to remove remaining part of the tri-layer mask; performing oxide etch on the device to be etched after the ODL removal to remove the oxide protective cap; and generating the contact on the device after the oxide etch. The present disclosure can accurately control the critical dimensions of the contact in an X direction and a Y direction.