Self-Aligned Gate Contact Plating for Semiconductor Interconnects
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the misalignment of gate contacts in field-effect transistors, leading to higher contact resistances and slower switching times due to limitations in photomask alignment tools, especially at smaller process nodes below 32 nm.
Innovation Solution
The solution involves a selective deposition process, such as electroless plating, where the gate contact is formed directly on the gate electrode without the need for photolithographic alignment, using metals like nickel, tungsten, or copper, ensuring exact alignment and reducing the reliance on mask alignment tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithographic alignment tools are used to form gate contacts, then the manufacturing process can be completed, but misalignment occurs leading to high contact resistance and slow switching times
Solution Approach 1:
The gate electrode itself serves as the alignment reference for forming the gate contact. The plating process automatically aligns the gate contact to the gate electrode without requiring external photolithographic alignment tools, eliminating misalignment issues while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces the mechanical photolithographic alignment system with an electrochemical plating system. Instead of using photomasks and alignment tools to define the gate contact position, the system uses selective plating on the gate electrode surface, where the gate electrode's physical presence directs the material deposition automatically
2Ease of manufacture
If photomask alignment steps are used, then gate contacts can be formed, but the process complexity increases and alignment errors occur at small scales below 32 nm
Solution Approach 1:
The patent extracts and removes the photolithographic alignment steps from the gate contact formation process. By eliminating the photomask alignment subsystem entirely, the process becomes simpler and avoids the inherent alignment errors that plague photolithographic methods at sub-32 nm scales
Solution Approach 2:
The gate electrode automatically defines the gate contact location through its physical presence during plating. This self-aligning mechanism eliminates the need for complex photomask alignment procedures, making the process easier to manufacture while achieving superior precision at small scales
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates misalignment issues, reduces contact resistance, and facilitates faster fabrication by eliminating the need for mask formation and etching steps, enabling precise and efficient formation of gate contacts even at small scales.
Implementation Method 1
One acceptable technique for the selective deposition is by plating. Plating is one process by which a metal structure, such as a gate contact, may be formed directly on the gate electrode. The plating is carried out by immersing the semiconductor die in a plating solution with the gate electrode exposed.
Data Source
AI summary
According to one embodiment of the invention, the gate contact is formed by a selective deposition on the gate electrode. One acceptable technique for the selective deposition is by plating. Plating is one process by which a metal structure, such as a gate contact, may be formed directly on the gate electrode. The plating is carried out by immersing the semiconductor die in a plating solution with the gate electrode exposed. The gate contact is plated onto the gate electrode and thus is ensured of being fully aligned exactly to the gate electrode. After this, the appropriate dielectric layers are formed adjacent the gate contact and over the source and drain to ensure that the gate electrode is electrically isolated from other components of the transistor.