Stacked Transistor Gate Structures With Independent Width Control
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Solution Overview
Problem
The complexity of manufacturing integrated circuit devices with stacked transistors makes the process challenging, and existing technologies struggle to efficiently form gate structures with varying dimensions and materials for optimal performance.
Innovation Solution
The method involves forming lower and upper gate structures through separate processes, allowing for independent adjustment of dimensions and materials, using a replacement metal gate process and spacer layers to achieve desired performance in integrated circuit devices with stacked transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If stacked transistors are used to reduce area, then area efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The gate structure is segmented into multiple gates (first gate, second gate, third gate) with different materials and dimensions, allowing independent optimization of each gate's characteristics while maintaining the stacked transistor architecture. This segmentation enables tailored performance for each transistor layer without requiring complete redesign of the entire stack.
Solution Approach 2:
Different gate structures are assigned to different regions of the stacked transistor based on local performance requirements. The first gate has different dimensions and material composition than the second and third gates, allowing each region to have optimized electrical characteristics suitable for its specific function within the device.
2Reliability
If gate structures with varying dimensions and materials are formed, then device performance is improved, but manufacturing complexity increases
Solution Approach 1:
A sacrificial gate structure is formed first as a template before the actual multi-material gate structures are created. This preliminary structure guides the subsequent formation of gates with different materials and dimensions, ensuring proper alignment and spacing without requiring complex direct patterning of each gate layer.
Solution Approach 2:
The sacrificial gate structure serves as an intermediary element that facilitates the formation of the final multi-material gate structure. It is temporarily present during manufacturing to enable precise positioning, then removed and replaced with the actual functional gates having different materials and dimensions.
3Adaptability or versatility
If separate formation processes are used for lower and upper gate structures, then manufacturing flexibility is improved, but process complexity increases
Solution Approach 1:
The gate formation process is segmented into separate stages for lower and upper gates, allowing independent optimization of materials, dimensions, and fabrication parameters for each gate type. This process segmentation provides flexibility to tailor each gate's characteristics without constraining the other gates in the stack.
Solution Approach 2:
The manufacturing process is made dynamic and adaptable through separate formation sequences, where the timing, materials, and dimensions of each gate can be independently adjusted based on performance requirements. This dynamic approach allows optimization of each gate's formation process without fixed constraints from other gates.
Data Source
AI summary
Integrated circuit devices may include a lower transistor and an upper transistor stacked on a substrate, and the upper transistor may overlap the lower transistor. The upper transistor may include an upper gate structure, and the lower transistor may include a lower gate structure, and the upper gate structure and the lower gate structure may have different widths in a horizontal direction.