Silicon Resist Underlayer Composition for Pattern Collapse Suppression
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Solution Overview
Problem
In the context of miniaturized pattern formation in Large-Scale Integrated circuits, existing photoresist compositions face challenges with pattern collapse and etching resistance, particularly when using thinner films with lower etching resistance, and there is a need for a material and process to reliably transfer patterns to substrates without defects.
Innovation Solution
A composition comprising a quaternary ammonium salt and thermally crosslinkable polysiloxane is used to form a silicon-containing resist underlayer film, which acts as a crosslinking catalyst, preventing pattern collapse and enabling precise pattern transfer through appropriate etching rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the photoresist film is reduced to achieve pattern miniaturization, then the resolution is improved, but the pattern collapse problem occurs due to large aspect ratio
Solution Approach 1:
The patent introduces a silicon-containing underlayer film as an additional dimension between the photoresist film and substrate. This underlayer provides mechanical support to prevent pattern collapse while allowing the photoresist film to be made thinner for high resolution patterning.
Solution Approach 2:
The silicon-containing underlayer film acts as an intermediary layer that mediates between the photoresist film and substrate. It provides etching selectivity and mechanical support, enabling the photoresist to maintain fine patterns without collapsing during the etching process.
2Manufacturing precision
If the photoresist film thickness is reduced for miniaturization, then the resolution is improved, but the etching resistance becomes insufficient
Solution Approach 1:
The patent adds a silicon-containing underlayer film as a separate functional layer that provides the necessary etching resistance. This allows the photoresist film to be thin for high resolution while the underlayer compensates for the insufficient etching resistance.
Solution Approach 2:
The patent uses a composite structure consisting of the photoresist film and silicon-containing underlayer film. Each layer performs its specific function: the photoresist provides pattern definition while the silicon underlayer provides etching resistance, together solving the contradiction between thin film requirement and etching resistance.
3Manufacturing precision
If a novolak resin or polyhydroxystyrene is used to reduce light absorption and improve resolution, then the resolution is improved, but the etching rate increases under dry etching conditions
Solution Approach 1:
The silicon-containing underlayer film acts as an intermediary that provides the necessary etching resistance. By using this underlayer, the patent can employ novolak or polyhydroxystyrene photoresists with low light absorption for high resolution without suffering from insufficient etching resistance.
Solution Approach 2:
The composite structure of photoresist film and silicon-containing underlayer film allows the photoresist to be optimized for resolution (using low-absorption materials like novolak) while the silicon underlayer compensates for the reduced etching resistance, maintaining appropriate etching rates.
4Manufacturing precision
If fluorine-based gas plasma is used to etch the silicon-containing underlayer film, then the pattern transfer is achieved, but the etching rate is insufficient causing residue and defects
Solution Approach 1:
The patent modifies the etching parameters by using oxygen-based or hydrogen-based gas plasma instead of fluorine-based gas plasma for etching the silicon-containing underlayer film. This parameter change achieves both sufficient etching rate and complete removal of the underlayer without leaving residue that would cause defects.
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 composition effectively suppresses pattern collapse and ensures high etching selectivity, allowing for the successful transfer of ultrafine patterns to substrates with minimal defects and efficient removal of the underlayer film, enhancing the yield and quality of semiconductor device patterns.
Implementation Method 1
a quaternary ammonium salt shown by general formula (A-1)... acts as a crosslinking catalyst
Implementation Method 2
thermally crosslinkable polysiloxane (Sx)... promoting thermal crosslinking
Implementation Method 3
the pattern is transferred to the underlayer film by dry etching using the resist upper layer film pattern as a dry etching mask
Data Source
AI summary
A composition for forming a silicon-containing resist underlayer film contains at least one or more kinds of a quaternary ammonium salt shown by the following general formula (A-1), and a thermally crosslinkable polysiloxane (Sx), where Ar1 represents an aromatic group having 6 to 20 carbon atoms, or a heteroaromatic group having 4 to 20 carbon atoms. R11 represents an alkyl group, alkenyl group, oxoalkyl group, or oxoalkenyl group having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group or aryloxoalkyl group having 7 to 12 carbon atoms. Some or all of hydrogen atoms of these groups are optionally substituted. Z− represents an organic or inorganic anion as a counterion of the quaternary ammonium cation. An object is to provide a silicon-containing resist underlayer film having high effect of suppressing ultrafine pattern collapse and appropriate etching rate in multilayer resist methods.