GAA Isolation Gate Structure for Leakage and Short-Channel Control
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Solution Overview
Problem
The integration of gate-all-around (GAA) transistor features in semiconductor fabrication is challenging, requiring improved methods to enhance gate control and reduce OFF-state current and short-channel effects.
Innovation Solution
A method involving the formation of a semiconductor device structure that includes patterning fin structures, forming isolation structures, and creating gate-all-around transistor structures by using photolithography and self-aligned processes, with specific etching and deposition techniques to form nanostructures and gate structures, ensuring minimal damage to underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate-all-around transistor structures are integrated into semiconductor fabrication, then gate control is enhanced and OFF-state current is reduced, but fabrication complexity increases
Solution Approach 1:
The fabrication process is divided into distinct stages: forming sacrificial nanowire structures, depositing gate materials, removing sacrificial material, and forming source/drain regions. Each stage independently contributes to the final GAA structure, making the complex process more manageable and controllable
Solution Approach 2:
Sacrificial nanowire structures are formed in advance before the actual gate structures are created. These preliminary structures serve as templates that guide subsequent fabrication steps, enabling precise gate-all-around formation while simplifying the overall process
2Reliability
If gate-all-around transistor structures are integrated into semiconductor fabrication, then OFF-state current is reduced and short-channel effects are reduced, but fabrication difficulty increases
Solution Approach 1:
Sacrificial nanowire structures act as intermediary elements that facilitate the formation of gate-all-around transistors. These intermediaries enable precise material deposition and structure formation, reducing fabrication difficulty while achieving the desired electrical performance
Solution Approach 2:
The gate structures are formed to completely surround the channel region, with inner and outer gates nested concentrically. This nested configuration enables better electrostatic control and reduces short-channel effects while maintaining fabrication feasibility through sequential deposition processes
Data Source
AI summary
A method for forming a semiconductor device structure includes forming a fin structure over a substrate. The method also includes forming a gate structure across the fin structure. The method also includes forming source/drain epitaxial structures over opposite sides of the gate structure. The method also includes forming a hard mask layer over the gate structure and the source/drain epitaxial structures. The method also includes removing a portion of the hard mask layer and the gate structure to form an opening. The method also includes laterally etching the gate structure to enlarge the opening under the hard mask layer. The method also includes depositing a shell material in the opening. The method also includes etching back the shell material to form a shell structure under the hard mask layer. The method also includes forming an isolation gate structure in the opening.