Protective Film Composition for Semiconductor Wet Etching
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Solution Overview
Problem
Existing protective films for semiconductor substrates fail to provide adequate masking against semiconductor wet etching solutions and are not resistant enough to ozonated solutions used in lithography processes.
Innovation Solution
A protective-film forming composition containing a polymer with no aromatic ring in its main chain, but with at least one oxirane or oxetane ring, is used to form a protective film that resists semiconductor wet etching solutions and ozonated solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional protective film is used, then the substrate can be protected during processing, but the film shows poor resistance to semiconductor wet etching solutions and ozonated solutions
Solution Approach 1:
The patent changes the chemical composition parameters of the protective film by specifying precise compositional ratios: polymer content (5-50 wt%), crosslinking agent content (5-50 wt%), and specific functional groups (oxirane/oxetane rings). This parameter optimization enables the film to achieve excellent resistance to both wet etching solutions and ozonated solutions while maintaining protective functionality.
Solution Approach 2:
The patent creates a composite protective film system combining multiple components: polymer base material, crosslinking agent, and specific functional groups (oxirane/oxetane rings). This composite structure provides synergistic effects where the crosslinking agent forms a three-dimensional network that enhances resistance to chemical degradation while the polymer matrix maintains film integrity and protective properties.
2Reliability
If the protective film contains aromatic rings in the main chain, then the film can be formed with good coverage, but the film shows poor resistance to ozonated solutions
Solution Approach 1:
The patent extracts and removes aromatic rings from the polymer main chain structure, replacing them with aliphatic structures containing oxirane or oxetane rings. This extraction of harmful aromatic groups eliminates the film's vulnerability to ozonated solutions while maintaining the necessary film-forming capabilities through alternative cyclic ether structures.
Solution Approach 2:
The patent applies local quality by introducing specific functional groups (oxirane or oxetane rings) at particular locations within the polymer structure. These localized functional groups provide targeted resistance to ozonated solutions and wet etching chemicals without requiring the entire polymer structure to be complex, thus achieving protection with controlled structural simplicity.
3Reliability
If the protective film is made with high crosslinking density, then the film shows improved resistance to chemical solutions, but the film formation becomes more difficult and requires stricter process control
Solution Approach 1:
The patent applies partial action by using controlled amounts of crosslinking agent (5-50 wt%) rather than maximum crosslinking density. This partial crosslinking approach provides sufficient chemical resistance while avoiding the manufacturing difficulties and process control strictures associated with highly crosslinked systems. The balanced formulation achieves adequate protection without excessive complexity.
Data Source
AI summary
A protective-film forming composition for forming a protective film that protects an inorganic film formed on a surface of a semiconductor substrate against wet etching, the composition containing: a polymer that contains no aromatic ring in a main chain and contains at least one of an oxirane ring and an oxetane ring; and a solvent.