Resist Polymer Narrow Molecular Weight Distribution
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Solution Overview
Problem
Current resist polymers used in DUV excimer laser and electron beam lithography suffer from defects such as voids in resist patterns, disconnection of circuits, and decreased yield due to broad molecular weight distribution and sensitivity changes during storage, particularly when using sulfur-containing chain transfer agents or specific solvents like PGMEA.
Innovation Solution
A resist polymer is developed with specific constituent units, including a lactone skeleton, an acid-eliminable group, and a hydrophilic group, polymerized using a hydroxy group-containing ester solvent, ensuring a narrow molecular weight distribution and improved storage stability, which enhances the resist composition's sensitivity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sulfur-containing chain transfer agents are used to produce resist polymers, then molecular weight distribution is narrowed, but decomposition of photoacid generator is promoted and sensitivity deteriorates during storage
Solution Approach 1:
The patent removes sulfur-containing chain transfer agents from the polymerization process entirely. Instead, it uses a novel chain transfer agent comprising a carboxylic acid and a specific compound (formula 1) that does not contain sulfur, thereby extracting the harmful sulfur element from the system while maintaining the desired molecular weight distribution control.
Solution Approach 2:
The patent introduces a new chain transfer agent system using carboxylic acid and compound (formula 1) as intermediaries to control polymerization. This intermediary system achieves narrow molecular weight distribution without the harmful side effects of sulfur-containing agents, specifically preventing photoacid generator decomposition during storage.
2Ease of operation
If carboxylic acid terminals are used to increase alkali solubility, then development velocity is improved, but elimination reaction of functional groups occurs during storage and sensitivity deteriorates
Solution Approach 1:
The patent extracts the problematic free carboxylic acid terminals from the polymer structure by using carboxylic acid as a controlled chain transfer agent during polymerization. This approach maintains sufficient alkali solubility for good development velocity while preventing the elimination reactions that occur with free carboxylic acid terminals during storage.
Solution Approach 2:
The patent changes the chemical state of carboxylic acid groups from free terminals (prone to elimination reactions) to controlled chain transfer agent-derived structures. This parameter change maintains the necessary alkali solubility for development while improving storage stability by preventing functional group elimination.
3Adaptability or versatility
If PGMEA and related solvents are used as polymerization solvents, then solubility in resist solvent is improved, but molecular weight distribution broadens and development defects occur
Solution Approach 1:
The patent extracts PGMEA and related esters from the polymerization solvent system. Instead, it employs water or alcohols as polymerization solvents, thereby eliminating the cause of broad molecular weight distribution and development defects while maintaining adequate solubility through the chosen chain transfer agent system.
Solution Approach 2:
The patent changes the polymerization solvent from organic esters (PGMEA) to water or alcohols. This parameter change fundamentally alters the polymerization kinetics to produce narrow molecular weight distribution while the resulting polymer structure maintains sufficient solubility in resist solvents for proper development.
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 new resist polymer achieves high sensitivity, resolution, and storage stability with reduced defects, enabling the production of highly accurate and fine resist patterns suitable for DUV excimer laser and electron beam lithography without the use of sulfur-containing agents, thus improving the productivity and quality of semiconductor substrates.
Implementation Method 1
a resist polymer (Y') containing a polymer (Y) comprising: a constituent unit (A) having a lactone skeleton, a constituent unit (B) having an acid-eliminable group, a constituent unit (C) having a hydrophilic group
Implementation Method 2
a constituent unit (B) having an acid-eliminable group
Implementation Method 3
a constituent unit (C) having a hydrophilic group
Data Source
AI summary
A resist polymer (Y′), which is used as a resist resin in DUV excimer laser lithography, electron beam lithography, and the like, contains a polymer (Y) comprising: a constituent unit (A) having a lactone skeleton; a constituent unit (B) having an acid-eliminable group; a constituent unit (C) having a hydrophilic group; and a constituent unit (E) having a structure represented by the following formula (1), wherein a content of the constituent unit (E) is 0.3 mol % or more based on the total number of the constituent units of the resist polymer (Y′):in the formula (1), L is a divalent linear, branched, or cyclic C1-20 hydrocarbon group which may have a substituent and/or a heteroatom; R11 is a g-valent linear, branched, or cyclic C1-20 hydrocarbon group which may have a substituent and/or a heteroatom; and g represents an integer of 1 to 24.