Semiconductor Interconnects Fine Pitch Plasma Etching

The patent segments the patterning process into multiple stages: first forming mandrels at relaxed pitch, then using those mandrels as templates to define spacer positions, and finally forming the final interconnect pattern. This multi-stage segmentation allows achieving fine pitch that exceeds single-step lithography capabilities.

The patent performs preliminary actions by first forming the mandrel structure and spacer layer before defining the final interconnect pattern. The mandrels are formed in advance as templates, and spacers are deposited beforehand to establish the precise spacing geometry needed for fine pitch features.

The patent introduces mandrels and spacers as intermediary structures that mediate between the lithography process and the final interconnect pattern. The mandrels serve as templates that define spacer positions, and the spacers act as intermediaries that transfer the pattern to the final interconnect layer, thereby reducing line width roughness and defects.

The patent changes the geometric parameters of the patterned layers by using spacers with controlled thickness and aspect ratios. By adjusting spacer dimensions and material properties, the final interconnect line width and roughness are optimized for reduced defects and improved reliability.

The patent changes etching process parameters by introducing hydrogen gas during plasma etching. This modifies the chemical environment to enhance etching selectivity between different materials layers, enabling precise pattern definition while maintaining process control.

The patent employs composite material structures with multiple dielectric layers having different etch selectivities. By designing the stack with materials that exhibit distinct etching responses, the process achieves superior pattern definition through selective removal of sacrificial layers while preserving the final interconnect pattern.