ARC Layer Etch via Carbon-Fluorine Ratio Adjustment
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving high device density and pattern transfer fidelity at sub-30 nm technology nodes due to issues like low resist budget, incoming defectivity, critical dimension control, line edge roughness, and line width roughness, particularly in the use of optical lithography and other advanced patterning strategies.
Innovation Solution
A plasma etch process is employed to pattern a silicon containing anti-reflective coating (ARC) layer, where a specific gas mixture and process conditions are used to enhance etch selectivity and reduce pattern roughness by modulating passivation during etching, allowing for improved transfer of feature patterns into the ARC layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etch processes are used to pattern the silicon containing ARC layer, then the pattern transfer can be achieved, but the etch selectivity is insufficient and line edge/width roughness increases
Solution Approach 1:
The patent modifies the plasma process parameters by adjusting the carbon-to-fluorine ratio in the process gas and controlling the plasma power and pressure conditions. This changes the chemical composition and reactivity of the plasma species, enabling selective etching of the silicon-containing ARC layer while minimizing damage to the patterned layer above, thus reducing line edge and width roughness
Solution Approach 2:
The patent introduces a passivation layer formed by carbon-containing plasma species that acts as an intermediary protective barrier. This passivation layer selectively protects the patterned layer while allowing etching of the ARC layer, thereby improving etch selectivity and reducing pattern roughness without compromising pattern transfer fidelity
2Object-generated harmful factors
If the etch selectivity is increased to protect the patterned layer, then line edge roughness is reduced, but the etch rate may be compromised
Solution Approach 1:
The patent employs a multi-step plasma etch process with periodic alternation between etching steps and passivation steps. During etching steps, fluorine-containing plasma removes the ARC layer; during passivation steps, carbon-containing plasma deposits protective layers. This periodic action maintains high etch rates while continuously reducing line edge roughness through selective passivation
Solution Approach 2:
The patent uses a composite plasma chemistry system combining carbon-containing gases (e.g., CF4, C4F8) and fluorine-containing gases (e.g., SF6). This composite approach creates plasma with dual functionality: carbon species provide passivation to reduce roughness, while fluorine species provide etching capability to maintain productivity, achieving both goals simultaneously
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The plasma etch process increases etch selectivity and reduces line edge and width roughness, enabling more precise and robust pattern transfer with minimal defectivity, thus addressing the limitations of existing methodologies.
Implementation Method 1
igniting plasma from the process gas using a plasma source
Data Source
AI summary
A method of patterning a silicon containing ARC (anti-reflective coating) layer underlying a patterned layer is described that includes establishing a flow of a process gas to a plasma processing system, selecting a process condition that increases an etch selectivity of the silicon containing ARC layer relative to the patterned layer, igniting plasma from the process gas using a plasma source in accordance with the process condition, and exposing the substrate to the plasma to extend the feature pattern of the patterned layer into the silicon containing ARC layer. The composition of the process gas and the flow rate(s) of the gaseous constituents in the process gas are selected to adjust the carbon-fluorine content.