Resist Underlayer Composition for ArF Lithography Etching
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Solution Overview
Problem
Existing resist underlayer films in lithography processes lack sufficient dry etching rates and solvent resistance, particularly when using acrylic resin-containing compositions, and do not easily form desired resist patterns with a rectangular cross-section.
Innovation Solution
A resist underlayer film forming composition containing a linear polymer with aromatic ring or nitrogen atom-containing structures, bonded with alkoxyalkyl or hydroxyalkyl groups, which can be self-crosslinked for improved curing and solvent resistance, along with specific solvents and additives for enhanced etching and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If acrylic resin-containing compositions are used to form resist underlayer films, then the composition is easily cured by heating, but the dry etching rate is insufficient and selection ratio is not satisfactory
Solution Approach 1:
The patent uses a composite polymer structure combining polyol units (providing crosslinking capability and solvent resistance) with polyester units (providing etch resistance through carbonyl groups). This composite structure achieves both easy curing through crosslinking and high dry etching rate selection ratio, resolving the contradiction between ease of manufacture and productivity.
2Ease of operation
If conventional polymer compositions are used, then the composition can be applied as liquid, but the formed film lacks sufficient solvent resistance
Solution Approach 1:
The patent changes the chemical structure parameters of the polymer by incorporating specific functional groups (hydroxyl, carboxyl, ester groups) and controlling the polymer architecture (linear chains with crosslinking capability). This enables the material to transition from a simple liquid application state to a crosslinked gel structure that provides both ease of application and superior solvent resistance.
3Manufacturing precision
If resist underlayer film is formed to suppress reflected wave influence, then exposure quality improves, but the film must maintain multiple conflicting properties simultaneously
Solution Approach 1:
The patent designs a universal polymer composition that simultaneously provides multiple functions: (1) optical properties for exposure quality control, (2) crosslinking capability for solvent resistance, (3) carbonyl groups for dry etching resistance, and (4) linear structure for ease of application. This multi-functional design reduces the complexity of meeting multiple separate material requirements.
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 high dry etching rate selection ratio and refractive index suitable for ArF excimer laser exposure, forming resist patterns with a rectangular cross-section and maintaining solvent resistance, thus improving the lithography process efficiency.
Implementation Method 1
a linear polymer having, in a main chain thereof, at least one of an aromatic ring-containing structure and a nitrogen atom-containing structure, and a solvent, in which to the aromatic ring or the nitrogen atom, at least one alkoxyalkyl group or hydroxyalkyl group is directly bonded
Implementation Method 2
When a resist underlayer film suppresses the influence of a reflected wave on a resist film during the exposure of the resist film
Data Source
AI summary
There is provided a composition for forming a resist underlayer film having a large selection ratio of dry etching rate, exhibiting desired values of the k value and the refractive index n at a short wavelength, for example, in an ArF excimer laser, and further, exhibiting solvent resistance. A resist underlayer film forming composition for lithography comprises a linear polymer having, in a main chain thereof, at least one of an aromatic ring-containing structure and a nitrogen atom-containing structure; and a solvent, wherein to the aromatic ring or the nitrogen atom, at least one alkoxyalkyl group or hydroxyalkyl group is directly bonded.