GAA Gate Structure Layout With Capping Layer Isolation
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Solution Overview
Problem
Integration of gate-all-around (GAA) transistor structures in semiconductor devices is challenging due to fabrication complexities, particularly in achieving precise patterning and gate control.
Innovation Solution
A method involving double-patterning or multi-patterning processes is employed to form GAA transistors, utilizing sacrificial layers, spacers, and capping layers to isolate adjacent gate structures, allowing for reduced device cell height and lower aspect ratios, along with the use of high-k dielectric materials and metal gate electrodes to enhance gate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-patterning methods are used to form GAA transistors, then the fabrication process is simpler, but manufacturing precision and gate control are insufficient
Solution Approach 1:
The patent applies segmentation by dividing the patterning process into multiple stages through double-patterning or multi-patterning techniques. First, a mandrel structure is formed and patterned, then sacrificial layers are deposited and patterned separately, followed by spacer formation. This multi-stage approach breaks down the complex patterning requirement into manageable segments, achieving higher precision (sub-10nm features) while maintaining process feasibility through systematic decomposition of the fabrication steps.
Solution Approach 2:
The patent employs preliminary action by forming mandrel structures and sacrificial layers before the final gate structure is created. The mandrel is formed first as a template, then sacrificial layers are deposited conformally on the mandrel and patterned. This preliminary structuring establishes precise geometric boundaries that guide subsequent spacer formation and material deposition, ensuring high manufacturing precision in the final GAA transistor structure before the actual gate is formed.
2Reliability
If gate-all-around structures are implemented to improve gate control, then short-channel effects are reduced, but fabrication complexity increases
Solution Approach 1:
The patent implements the nested doll principle by creating a hierarchical structure where spacers are formed around sacrificial layers, which themselves surround mandrel structures. The gate material is then deposited to wrap around these nested structures, forming a gate-all-around configuration. This nesting approach allows the gate to completely surround the channel region (providing superior gate control and reduced short-channel effects) while using systematic, repeatable deposition and etching steps that manage fabrication complexity through modular processing.
Solution Approach 2:
The patent uses intermediary elements (mandrels and sacrificial layers) that facilitate the formation of the gate-all-around structure but are eventually removed. The mandrel serves as an initial template, and sacrificial layers act as intermediaries that define the channel region during spacer formation. These intermediary structures enable precise gate-all-around formation without requiring direct complex patterning of the gate itself, thus improving gate control while managing fabrication complexity through temporary assisting structures.
3Manufacturing precision
If double-patterning or multi-patterning processes are used, then manufacturing precision is improved, but the number of fabrication steps increases
Solution Approach 1:
The patent applies merging by combining multiple patterning operations into an integrated process flow. The mandrel formation, sacrificial layer deposition, spacer formation, and gate material deposition are merged into a unified sequence where each step builds on the previous one. For example, the same spacer formation technique is used both to define the channel region and to prepare for gate deposition, and the etch processes for removing mandrels and sacrificial layers are combined into a single selective removal step. This merging maintains high manufacturing precision while improving fabrication efficiency by reducing the total number of discrete process modules.
Data Source
AI summary
A semiconductor device structure includes nanostructures over a substrate and a gate structure surrounding the nanostructures. The semiconductor device structure also includes a fin isolation structure beside the nanostructures. The semiconductor device structure further includes a capping layer over the fin isolation structure. In addition, the semiconductor device structure includes a gate contact structure over the gate structure. The gate structure covers a top surface of an extending portion of the capping layer.