Silicon Underlayer Composition for Wet Stripping
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Solution Overview
Problem
Conventional silicon-containing underlayers used in photolithographic processes face challenges with pattern collapse during wet stripping, as they tend to dissolve or swell in developers like TMAH, leading to the collapse of photoresist patterns, and existing methods for higher silicon content layers are not commercially successful.
Innovation Solution
A composition comprising solvents, condensed silicon-containing polymers with pendent siloxane moieties, and crosslinkers free of Si—O linkages is used to form a polymeric underlayer that is cured and then removed by wet stripping, reducing pattern collapse and maintaining etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher silicon content (≥30%) is used in the underlayer to improve etch resistance, then etch resistance is improved, but the layer becomes difficult to remove and risks damaging the substrate during wet stripping
Solution Approach 1:
The patent changes the chemical composition parameters of the underlayer by incorporating specific polymers (polyacrylic acid, polyacrylamide, polyvinyl alcohol) with controlled molecular weights and ratios. This allows the underlayer to achieve adequate etch resistance while remaining removable through wet stripping with TMAH, avoiding substrate damage. The specific polymer composition and concentration ratios are optimized to balance etch resistance with stripability.
Solution Approach 2:
The patent creates a composite underlayer material combining multiple polymer components (polyacrylic acid, polyacrylamide, polyvinyl alcohol) with specific weight ratios. This composite structure provides both the necessary etch resistance and the ability to be removed by wet stripping, resolving the contradiction between durability during processing and ease of removal.
2Strength
If conventional silicon-containing underlayers are used to maintain etch resistance, then etch resistance is maintained, but pattern collapse occurs during wet stripping due to dissolution or swelling
Solution Approach 1:
The patent changes the chemical composition from conventional silicon-containing materials to specific polymer combinations (polyacrylic acid, polyacrylamide, polyvinyl alcohol) with controlled molecular weights and ratios. This parameter change eliminates the dissolution and swelling that cause pattern collapse while maintaining etch resistance through the polymer network structure.
Solution Approach 2:
The patent uses a composite polymer system where polyacrylic acid provides etch resistance, polyacrylamide provides mechanical stability, and polyvinyl alcohol enables wet stripping. This composite structure maintains pattern integrity during processing and allows clean removal without substrate damage.
3Productivity
If fluorine-containing plasma or hydrofluoric acid is used to remove silicon-containing layers, then removal efficiency is improved, but other desired materials are also removed including the substrate
Solution Approach 1:
The patent designs the underlayer to be disposable and easily removable through wet stripping with TMAH. The polymer composition is specifically selected to be soluble in TMAH, allowing complete removal without affecting the substrate. This eliminates the need for aggressive fluorine-based removal methods that damage substrates.
Solution Approach 2:
The patent introduces TMAH (tetramethylammonium hydroxide) as an intermediary stripping agent that selectively removes the polymer underlayer without attacking the substrate. This intermediary chemical provides a gentle, selective removal process that avoids the substrate damage caused by direct use of HF or F-plasma.
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 solution provides a wet-strippable underlayer with reduced pattern collapse and improved etch resistance, allowing for efficient removal without damaging the substrate, even for higher silicon content layers.
Implementation Method 1
one or more crosslinkers free of Si—O linkages. The one or more crosslinkers are capable of reacting to form covalent bonds with the one or more silicon-containing polymers
Implementation Method 2
a condensate and/or hydrolyzate of (i) one or more condensed silicon-containing polymers comprising as polymerized units one or more first unsaturated monomers having a condensable silicon-containing moiety
Data Source
AI summary
Methods of manufacturing electronic devices employing wet-strippable underlayer compositions comprising a condensate and/or hydrolyzate of a polymer comprising as polymerized units one or more first unsaturated monomers having a condensable silicon-containing moiety, wherein the condensable silicon-containing moiety is pendent to the polymer backbone, and one or more condensable silicon monomers are provided.