Fluorinated Polyimide Resin for Low-Stress Semiconductor Insulation
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Solution Overview
Problem
The development of a resin composition that balances low stress, high adhesiveness to substrates, and storage stability is challenging, particularly for low-k interlayer insulating films in semiconductor manufacturing, where polyimide resins with fluorine can reduce adhesiveness but increase stress, and isocyanate-based compositions have reactivity issues.
Innovation Solution
A resin composition comprising a polyimide precursor with specific structural units and a compound that generates radicals upon irradiation, combined with an adhesion aid, to form a low-stress cured film with improved adhesiveness and storage stability, using components like pyromellitic dianhydride, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and oxime ester compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyimide resin with high thickness and high modulus elasticity is used to protect the low-k layer, then mechanical strength is improved, but stress after curing increases causing wafer warpage
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide precursor by introducing fluorine atoms at specific positions (R10-R17) and controlling the ratio of rigid to flexible structural units. This modifies the curing behavior and stress characteristics of the resin, enabling high mechanical strength with reduced curing stress that prevents wafer warpage
Solution Approach 2:
The patent creates a composite resin system combining polyimide precursor with specific fluorinated structural units (General Formula 5 or 6) and other functional units (General Formula 1-4). This composite structure achieves synergistic effects where the fluorinated units reduce stress while maintaining or enhancing mechanical properties
2Strength
If a resin film with large thickness is formed to protect the low-k layer, then mechanical protection is improved, but i-line transmittance is lowered making pattern formation impossible
Solution Approach 1:
The patent modifies the optical parameters of the resin by incorporating fluorine atoms into the polyimide precursor structure. Fluorine substitution reduces the refractive index and improves light transparency, allowing thick films to maintain high i-line transmittance for effective photolithography patterning
3Illumination intensity
If a polyimide precursor containing fluorine is used to increase i-line transmittance, then transmittance is improved, but adhesiveness to silicon wafer is lowered
Solution Approach 1:
The patent applies local quality by positioning fluorine atoms at specific locations (R10-R17) in the molecular structure rather than uniformly throughout. This localized fluorination optimizes optical properties while preserving adhesive functional groups at other positions, maintaining both transmittance and adhesiveness
4Reliability
If 3-isocianatopropyltriethoxysilane is used to attain excellent adhesiveness with silicon wafer, then adhesiveness is improved, but storage stability is lowered due to high reactivity of isocyanate group
Solution Approach 1:
The patent uses silane coupling agents as intermediary substances that bridge the polyimide resin and silicon wafer substrate. The silane groups provide adhesive functionality while the organic bridging structure reduces direct reactivity issues, improving storage stability while maintaining excellent adhesiveness to silicon wafers
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 achieves a low residual stress of 30 MPa or less, excellent adhesiveness to silicon wafers, and enhanced storage stability, enabling smooth wafer transfer and pattern formation while maintaining high thermal resistance and i-line transmittance.
Implementation Method 1
a compound (c) that generates a radical upon irradiation with active rays
Data Source
AI summary
A resin composition including the following components (a) and (b). (a) A polyimide precursor having a structural unit represented by the following general formula (1); and (b) a compound represented by the following general formula (2): wherein in the formula R1 is a tetravalent organic group, R2 is a divalent organic group and R3 and R4 are independently a hydrogen atom, an alkyl group, a cycloalkyl group or a monovalent organic group having a carbon-carbon unsaturated double bond. R5 is an alkyl group having 1 to 4 carbon atoms, R6 is independently a hydroxyl group or an alkyl group having 1 to 4 carbon atoms, a is an integer of 0 to 3, n is an integer of 1 to 6, and R7 is a group represented by the following general formula (3) or (4): wherein in the formula (3) or (4), R8 is an alkyl group having 1 to 10 carbon atoms or a monovalent organic group derived from hydroxyalkylsilane and R9 is an alkyl group having 1 to 10 carbon atoms, a monovalent organic group derived from aminoalkylsilane or a heterocyclic group, and R8 and R9 may independently have a substituent.