SiBN Sacrificial Film Patterning for Sub-Resolution Features
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Solution Overview
Problem
The existing sacrificial films used in semiconductor patterning, such as silicon nitride and silicon oxide, face a dilemma where high-temperature formation increases strength but reduces etchability, while low-temperature formation enhances etchability but compromises strength, making it difficult to form patterns below the resolution limit with reproducibility and stability.
Innovation Solution
A patterning method involving the formation of a sacrificial film made of SiBN, which is processed into a preset pattern using photolithography, and then removed with sidewall spacers of a different material, allowing for the formation of underlying film patterns with widths below the resolution limit while maintaining strength and ease of removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sacrificial film is formed at a high temperature to increase strength, then the film strength is improved, but the film becomes difficult to etch and remove
Solution Approach 1:
The patent changes the material composition parameter of the sacrificial film from conventional silicon nitride or silicon oxide to SiBN (silicon boron nitride). This material parameter change enables the film to be formed at lower temperatures while maintaining sufficient strength, and simultaneously improves etchability by selecting etchants that selectively remove SiBN without damaging the sidewall spacer or underlying film.
Solution Approach 2:
The patent uses SiBN as a composite material that combines the desirable properties of silicon nitride (strength) and boron nitride (etch selectivity). This composite material allows the sacrificial film to have both adequate mechanical strength for forming sidewall spacers and high etch selectivity for easy removal, resolving the contradiction between strength and etchability.
2Ease of manufacture
If the sacrificial film is formed at a low temperature to enhance etchability, then the film becomes easily removed, but the film strength becomes weak and the film is easily damaged or etched during sidewall spacer formation
Solution Approach 1:
The patent changes the material composition parameter to SiBN, which can be formed at lower temperatures compared to conventional high-temperature silicon nitride films. The SiBN material maintains adequate strength at lower formation temperatures while providing superior etch selectivity, allowing easy removal with specific etchants like hot phosphoric acid without damaging other structures.
3Strength
If conventional sacrificial films (silicon nitride or silicon oxide) are used, then the film can be formed with sufficient strength, but the film cannot be easily removed without damaging the sidewall spacer or underlying film
Solution Approach 1:
The patent uses SiBN as a composite material that provides both adequate strength for sidewall spacer formation and high etch selectivity for reliable removal. The SiBN film can be selectively removed using hot phosphoric acid or other specific etchants that do not attack the sidewall spacer materials (such as silicon oxide or silicon nitride) or the underlying film, ensuring reliable selective removal without damage to other structures.
Solution Approach 2:
The patent introduces specific etchants (such as hot phosphoric acid) as intermediaries that selectively remove the SiBN sacrificial film without affecting the sidewall spacer or underlying film. This intermediary chemical agent enables the selective removal process to proceed reliably without direct mechanical or thermal damage to other sensitive structures.
Data Source
AI summary
Disclosed is a patterning method including: forming, on a thin film, a sacrificial film made of a material different from that of the thin film and made of SiBN; processing the sacrificial film into a pattern having a preset interval by using a photolithography technique; forming, on sidewalls of the processed sacrificial film, sidewall spacers made of a material different from those of the sacrificial film and the thin film; removing the processed sacrificial film; and processing the thin film by using the sidewall spacers as a mask.