Bottom Antireflective Coating Materials for Semiconductor Lithography
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Solution Overview
Problem
Conventional photolithography processes in semiconductor fabrication often result in residual photoresist material, or scum, on the underlayer due to the affinity between the photoresist layer and the underlayer, which complicates the patterning process and reduces yield.
Innovation Solution
The use of specific underlayer coating solutions, including those with fluorine-containing groups that can be cleaved off or permanently bonded, and a photobase generator with a thermal acid generator, to reduce the affinity between the photoresist layer and the underlayer, allowing for improved removal of residual photoresist material during development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional underlayer compositions are used, then the photolithography process can be performed, but residual photoresist material (scum) remains on the underlayer due to affinity between photoresist and underlayer
Solution Approach 1:
The patent modifies the chemical composition parameters of the underlayer by incorporating fluorinated compounds and specific polymers with controlled molecular weights and functional groups. These parameter changes reduce the surface energy and chemical affinity between the underlayer and photoresist, preventing scum formation while maintaining pattern fidelity during photolithography
Solution Approach 2:
The underlayer is formulated as a composite material system combining fluorinated polymers (such as聚 fluorinated styrene), crosslinking agents, and adhesion promoters. This composite structure provides both the low-affinity surface properties needed to prevent scum and the mechanical properties required for process stability, resolving the contradiction between pattern quality and scum reduction
2Productivity
If photoresist layer is deposited directly on underlayer, then the patterning process can proceed, but additional processing steps are required to remove residual photoresist
Solution Approach 1:
The underlayer is pre-treated with fluorinated compounds and adhesion promoters before photoresist deposition. This preliminary action creates an optimized surface that inherently reduces photoresist affinity, preventing scum formation at the source and eliminating the need for additional descumming process steps, thereby simplifying the overall fabrication process while maintaining productivity
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
These solutions effectively reduce scum formation, enlarge process windows, and enhance the yield by minimizing residual photoresist material, thereby improving the efficiency of semiconductor device fabrication.
Implementation Method 1
fluorine-containing groups that can be cleaved off or permanently bonded... to reduce the affinity between the photoresist layer and the underlayer
Implementation Method 2
a photobase generator with a thermal acid generator
Data Source
AI summary
A method according to the present disclosure includes providing a substrate, depositing an underlayer over the substrate, depositing a photoresist layer over the underlayer, exposing a portion of the photoresist layer and a portion of the underlayer to a radiation source according to a pattern, baking the photoresist layer and underlayer, and developing the exposed portion of the photoresist layer to transfer the pattern to the photoresist layer. The underlayer includes a polymer backbone, a polarity switchable group, a cross-linkable group bonded to the polymer backbone, and photoacid generator. The polarity switchable group includes a first end group bonded to the polymer backbone, a second end group including fluorine, and an acid labile group bonded between the first end group and the second end group. The exposing decomposes the photoacid generator to generate an acidity moiety that detaches the second end group from the polymer backbone during the baking.