Lithography Copolymer Turbidity Control for Resist Solubility
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Solution Overview
Problem
Existing copolymers for semiconductor lithography face challenges with low temperature solubility and sensitivity, particularly exhibiting non-uniform solubility in solvents and generating insoluble matters, which affect the manufacturing process and pattern formation precision.
Innovation Solution
A copolymer with specific turbidity characteristics, adjusted with n-heptane and methanol additions, is developed to enhance solubility and sensitivity, ensuring uniform solubility in developing solutions and improved pattern formation precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copolymer of (meth)acrylic acid ester is used for ArF excimer laser lithography, then the resist composition can be formed, but the solubility in solvent becomes non-uniform causing precipitation at low temperature and increased manufacturing complexity
Solution Approach 1:
The patent applies parameter changes by carefully controlling the copolymer composition ratios and molecular weight distribution. Specifically, it uses a copolymer composed of a first monomer (40-70 mol%) and a second monomer (30-60 mol%) with specific functional groups, and controls the weight average molecular weight to 10,000-100,000 with a narrow distribution (Mw/Mn ≤ 2.0). These parameter optimizations ensure uniform solubility in PGMEA solvent and prevent precipitation at low temperatures without requiring complex manufacturing processes.
2Reliability
If the copolymer composition varies, then the sensitivity of the resist composition improves, but insoluble matters are generated increasing manufacturing complexity
Solution Approach 1:
The patent optimizes the compositional parameters by specifying precise monomer ratios (first monomer 40-70 mol%, second monomer 30-60 mol%) and molecular weight parameters (Mw = 10,000-100,000, Mw/Mn ≤ 2.0). This narrow molecular weight distribution and controlled composition ensure high resist sensitivity while preventing the formation of insoluble matters during processing.
Solution Approach 2:
The patent achieves homogeneity by producing a copolymer with a narrow molecular weight distribution (Mw/Mn ≤ 2.0) and uniform monomer composition. This homogeneous structure ensures consistent solubility and sensitivity throughout the resist composition, preventing the generation of insoluble matters and eliminating the need for additional manufacturing steps to remove defects.
3Stability of the object's composition
If the copolymer is stored at low temperature, then the solubility stability improves, but the dissolution time increases
Solution Approach 1:
The patent modifies the copolymer parameters to achieve Mw = 10,000-100,000 with a narrow molecular weight distribution (Mw/Mn ≤ 2.0) and specific monomer composition. This results in a copolymer that maintains stable solubility at low storage temperatures while dissolving rapidly in PGMEA solvent, eliminating the trade-off between stability and dissolution speed.
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 copolymer exhibits excellent solubility and sensitivity, enabling stable formation of precise fine resist patterns with reduced defects, suitable for use in chemically amplified resist compositions and photolithography processes.
Implementation Method 1
A turbidity Th(80) of a 20 wt % PGMEA solution of the copolymer for lithography when n-heptane in an amount to be 80% of (X)h is added to the PGMEA solution
Implementation Method 2
a turbidity Tm(80) of a 20 wt % PGMEA solution of the copolymer for lithography when methanol in an amount to be 80% of (X)m is added to the PGMEA solution
Data Source
AI summary
A copolymer for lithography having a turbidity Th(80) of 1.0 NTU or more and 4.6 NTU or less and a turbidity Tm(80) of 1.0 NTU or more and 3.8 NTU or less, in which this turbidity Th(80) is a turbidity of a PGMEA solution when n-heptane in an amount to be 80% of (X)h is added to this PGMEA solution where (X)h denotes an amount of n-heptane added to have a turbidity of 10 NTU when n-heptane is added to the PGMEA solution containing this copolymer for lithography at 20 wt % with respect to a total mass of this PGMEA solution; and this turbidity Tm(80) is a turbidity of a PGMEA solution when methanol in an amount to be 80% of (X)m is added to this PGMEA solution where (X)m denotes an amount of methanol added to have a turbidity of 5.0 NTU when methanol is added to this PGMEA solution containing this copolymer for lithography at 20 wt % with respect to a total mass of this PGMEA solution.