Resist Underlayer Film Material for High Aspect Ratio Patterning
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Solution Overview
Problem
Current resist underlayer films for semiconductor manufacturing face challenges in achieving high dry etching resistance, heat resistance, and filling/planarizing properties, particularly for fine-pattern structures with high aspect ratios, leading to issues like pattern collapse and insufficient adhesiveness.
Innovation Solution
A resist underlayer film material comprising a resin with a specific compound structure and an organic solvent, optimized for a weight-average molecular weight and molecular weight distribution, along with a crosslinking agent, surfactant, acid generator, plasticizer, and pigment, to enhance dry etching resistance, heat resistance, and filling/planarizing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoresist film thickness is reduced to enhance resolution for fine patterning, then resolution performance is improved, but dry etching resistance deteriorates
Solution Approach 1:
The invention divides the resist system into multiple functional layers: a photoresist film for pattern formation and an underlayer film for etching resistance. This segmentation allows each layer to be optimized independently - the photoresist film can be thin for high resolution while the underlayer film provides the necessary dry etching resistance, resolving the contradiction between resolution and etching resistance
Solution Approach 2:
The underlayer film uses a composite material system comprising a novolak resin backbone with grafted acrylic ester groups and crosslinked structures. This composite structure provides both the adhesion needed for thin film stability and the dry etching resistance required to protect the pattern during processing, enabling thin photoresist films to maintain sufficient etching resistance
2Manufacturing precision
If photoresist film thickness is reduced for fine patterning, then resolution is improved, but pattern collapse occurs due to excessive aspect ratio
Solution Approach 1:
By segmenting the resist system into photoresist film and underlayer film, the mechanical support function is separated from the pattern formation function. The underlayer film acts as a rigid foundation that reduces the aspect ratio of the overall resist structure, preventing pattern collapse while allowing the photoresist film to be thin for high resolution
Solution Approach 2:
The underlayer film modifies the mechanical parameters of the resist system by providing a stiff base layer with appropriate adhesion. This changes the effective aspect ratio and mechanical strength parameters, enabling thin photoresist films to maintain pattern stability during development and processing
3Manufacturing precision
If novolak resins are used for high resolution with shorter wavelength exposure, then resolution is improved, but etching resistance decreases
Solution Approach 1:
The underlayer film employs a composite material combining novolak resin (for resolution compatibility with short wavelength exposure) with grafted acrylic ester groups and crosslinked structures (for enhanced etching resistance). This composite approach allows the resin to maintain low absorbance at exposure wavelength while achieving sufficient dry etching resistance through the modified molecular structure and crosslinking
Solution Approach 2:
The molecular structure of the novolak resin is chemically modified by grafting acrylic ester groups and introducing crosslinks. This changes the physical and chemical parameters of the resin, particularly improving etching resistance while maintaining the optical properties needed for high resolution patterning with shorter wavelength light sources
4Manufacturing precision
If filling and planarizing properties are enhanced for fine-pattern structures, then film uniformity is improved, but adhesiveness may deteriorate
Solution Approach 1:
The molecular structure parameters of the underlayer film are optimized to balance filling/planarizing properties and adhesiveness. The specific composition ratio of novolak resin to acrylic ester groups, along with controlled crosslinking density, creates a material that has appropriate viscosity for good filling and planarization while maintaining sufficient chemical groups for adhesion to the substrate and photoresist film
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 material provides excellent dry etching resistance, heat resistance up to 500°C, and superior filling and planarizing properties, preventing defects like voids and peeling, and ensuring precise pattern transfer in semiconductor device manufacturing.
Implementation Method 1
heating to form a cured film
Implementation Method 2
excellent dry etching resistance
Data Source
Figure 1(A)~1(F)
Figure 2(G)~3(K)
AI summary
A resist underlayer film material contains (A) a resin having a compound shown in the following general formula (1A), and (B) an organic solvent. Mw/Mn of the compound shown in the general formula (1A) is 1.00≤Mw/Mn≤1.25. This provides: a resist underlayer film material having all of favorable dry etching resistance, heat resistance to 500°C or higher, and high filling and planarizing properties; and methods for forming a resist underlayer film and patterning processes which use the material.