Selective Spacer Etch Using Nitrogen-Activated Fluorosilicate Formation
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving optimal spacer sidewall profiles using reactive ion etch (RIE) for patterning, particularly in achieving selective etching of spacer films without damaging patterns and ensuring simultaneous selectivity to underlying films, which is crucial for subsequent patterning steps.
Innovation Solution
A method involving conformal spacer deposition and reactive ion etch processes using N-containing and F/H-containing gases to form fluorosilicates, allowing for controlled etch selectivity and preventing pattern damage, thereby enhancing the spacer sidewall mask profile and enabling better pattern density integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RIE processes are used for spacer etching, then etching speed is maintained, but selectivity to underlying films deteriorates and pattern damage occurs
Solution Approach 1:
The patent modifies the RIE process parameters by introducing N-containing gases (NH3, N2) in combination with F-containing gases (CF4, SF6). This changes the chemical composition of the plasma, enabling selective etching of oxide spacers while protecting underlying films through the formation of protective nitrogen-containing surface layers that reduce etch attack on sensitive materials.
Solution Approach 2:
The nitrogen-containing gas acts as an intermediary that mediates between the fluorine-based etch chemistry and the underlying film protection. The N-containing species adsorb on the film surface and form protective layers that prevent direct contact between aggressive F-based etchants and the underlying films, thereby enabling selective spacer removal without pattern damage.
2Productivity
If aggressive etching is used to remove spacers quickly, then productivity increases, but selectivity to underlying films and pattern integrity deteriorate
Solution Approach 1:
The patent achieves high etch rates with maintained precision by changing the gas chemistry from conventional F-based alone to a dual chemistry system incorporating N-containing gases. The nitrogen species provide surface passivation that protects patterns while allowing controlled removal of oxide spacers at acceptable rates, balancing productivity with pattern fidelity.
3Device complexity
If standard spacer deposition and etching is performed, then process simplicity is maintained, but spacer sidewall profile quality deteriorates
Solution Approach 1:
The patent improves spacer sidewall profile quality by modifying the etch chemistry parameters - specifically using N-containing gases to create a more controlled etching environment. This results in smoother sidewalls and better vertical profiles without adding significant process complexity, as the same RIE tool is used with modified gas recipes.
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
This approach enables selective etching of spacer films with enhanced selectivity to underlying layers, reducing pattern damage and achieving accurate critical dimension transfer, thus improving the efficiency and cost-effectiveness of multi-patterning schemes like SAQP and SADP.
Implementation Method 1
the second spacer RIE process includes adsorption of N containing gas on a surface of the substrate which activates the surface to react with an F and/or an H-containing gas to form fluorosilicates
Implementation Method 2
performing a second spacer RIE process and a second pull process, wherein generating a second spacer pattern
Data Source
AI summary
Provided is a method for increasing pattern density of a structure on a substrate using an integration scheme, the method comprising: providing a substrate having a first spacer pattern and an underlying layer, the underlying layer comprising a first underlying layer, a second underlying layer, and a target layer; performing a conformal spacer deposition using an oxide, the deposition creating a conformal layer; performing a spacer RIE process and a pull process, thereby generating a second spacer pattern, the spacer RIE process includes adsorption of N-containing gas on a surface of the substrate which activates the surface to react with an F- and/or an H-containing gas to form fluorosilicates; and wherein the integration targets include selectively etching spacer films within a target spacer etch rate, enhanced simultaneous selectivity to the first underlying layer and the second underlying layer and preventing pattern damage.