Multi-layer Imprint Lithography Residual Formation Reduction

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Solution Overview

Problem

In multi-layer imprint lithography, residual formation during etching processes is a challenge due to vitrification of polymerizable compositions, leading to micro-masking and silicon oxide residue formation, which affects the properties of the polymerized layers and subsequent processing steps.

Innovation Solution

Selecting a first polymerizable composition with a glass transition temperature (Tg) below 25°C to prevent vitrification, ensuring complete polymerization and impermeability to a second polymerizable composition, thereby reducing residue formation during etching. This involves using mono-functional and multi-functional polymerizable components with appropriate reactivity and additives to inhibit infiltration and promote bonding, and incorporating silicon-containing materials to minimize micro-masking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a polymerizable composition with high glass transition temperature is used, then the polymer behaves like a glassy material with restricted molecular mobility, but this leads to vitrification during polymerization and trapping of unreacted composition, causing micro-masking and residue formation

Engineering Contradiction:

Improvepolymer stabilityVSAvoidresidue formation

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent changes the glass transition temperature parameter of the polymerizable composition from above room temperature to below room temperature (specifically below 25°C). This parameter change prevents vitrification during polymerization, allowing complete reaction and eliminating trapped unreacted composition that would otherwise cause micro-masking and residue formation during etching

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful effect of restricted molecular mobility (which causes vitrification) into a beneficial outcome by selecting a polymer composition where the low glass transition temperature ensures sufficient molecular mobility during polymerization to complete the reaction, yet the polymer still provides the desired structural properties in the final product

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Adaptability or versatility

If the first polymerized layer is permeable to the second polymerizable composition, then the second composition can penetrate and intermix with unreacted first composition, but this alters the properties of the first layer and causes micro-masking during etching

Engineering Contradiction:

Improvelayer compatibilityVSAvoidetching reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by ensuring complete polymerization of the first layer before applying the second composition. By selecting a polymerizable composition with glass transition temperature below 25°C, the first layer achieves full polymerization and forms an impermeable barrier in advance, preventing subsequent penetration and intermixing that would compromise etching reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates local quality differences between the first and second layers by ensuring the first layer is completely polymerized and impermeable, while the second layer remains polymerizable. This local distinction in chemical state and permeability properties prevents unwanted intermixing and maintains the integrity of each layer during subsequent processing

Inventive Principle:

Principle #3Local quality

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 approach significantly reduces residual formation and micro-masking, enhancing the quality of multi-layer stacks by preventing infiltration and solidification of unreacted components, thus improving the reliability of subsequent processing steps and reducing unwanted residues.

Implementation Method 1

vitrification of polymerizable compositions

Methodology Applied

Scientific EffectVitrification: Vitrification

Implementation Method 2

polymerizing the first polymerizable composition to form a first polymerized layer

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Implementation Method 3

a first polymerizable composition with a glass transition temperature (Tg) below 25°C to prevent vitrification

Methodology Applied

Scientific EffectGlass transition:

Data Source

PatentEP2188831B1Reduced residual formation in etched multi-layer stacks

Publication Date: 2015.12.02 MOLECULAR IMPRINTS INC

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AI summary

A multi-layer stack for imprint lithography is formed by applying a first polymerizable composition to a substrate, polymerizing the first polymerizable composition to form a first polymerized layer, applying a second polymerizable composition to the first polymerized layer, and polymerizing the second polymerizable composition to form a second polymerized layer on the first polymerized layer. The first polymerizable composition includes a polymerizable component with a glass transition temperature less than about 25°C, and the first polymerized layer is substantially impermeable to the second polymerizable composition.