Source/Drain Contact Isolation Plug for Scaled GAA Transistors

The patent applies multi-patterning processes that divide the patterning operation into multiple sequential steps, where each step creates a portion of the final pattern. This segmentation allows achieving higher precision at scaled dimensions by breaking down the complex single-step patterning into manageable stages, thereby maintaining manufacturing precision while enabling continued scaling for improved productivity.

The patent employs preliminary patterning actions where mandrel structures and spacer layers are formed in advance before the final pattern transfer. These preliminary structures serve as templates that guide subsequent etching steps, ensuring precise feature formation at reduced geometries. This preliminary action enables accurate patterning to be achieved even as feature sizes decrease, maintaining precision while allowing continued scaling for higher productivity.

The patent implements nested structures where spacer layers are formed around mandrel structures, and subsequent patterns are defined relative to these nested elements. The multi-layer spacer and mandrel configuration creates a nested arrangement that enables precise GAA transistor patterning through self-aligned processes, improving device performance while the modular nested approach helps manage fabrication complexity by creating repeatable pattern units.

The patent transitions from two-dimensional planar patterning to three-dimensional GAA transistor structures with vertical channels surrounded by gates on multiple sides. This dimensional change enables superior device performance through enhanced gate control, while the use of self-aligned spacer formation and sequential patterning steps provides a systematic approach to managing the increased fabrication complexity inherent in three-dimensional structure creation.

The patent forms isolation plugs and contact structures in a sequential manner where preliminary isolation regions are defined before contact formation. The contact enlargement is achieved through controlled deposition and etching steps that build upon previously formed structures, improving electrical connection reliability while the sequential approach integrates the enlargement process into the existing fabrication flow, managing overall processing complexity.

The patent introduces isolation plugs as intermediary structures that mediate between the source/drain contacts and the substrate. These plugs serve multiple functions: providing electrical isolation, enabling contact enlargement through controlled deposition, and facilitating subsequent processing steps. The intermediary isolation plug structure allows contact size optimization for improved electrical connection while the modular design helps manage fabrication complexity by creating distinct, manageable processing stages.