Negative Tone Imaging Resist for Ultrafine Lithography

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Solution Overview

Problem

Current pattern forming methods, particularly in semiconductor manufacturing, face challenges in achieving ultrafine line and space patterns with line widths and space widths of 40 nm or less, as existing techniques often result in pattern damage, reduced film thickness, and limited resolution due to the limitations of ArF liquid immersion lithography and double patterning processes.

Innovation Solution

A pattern forming method involving the use of actinic ray-sensitive or radiation-sensitive resin compositions with increased polarity, which decreases solubility in organic solvents, allowing for two-stage patterning with heating processes to form ultrafine line and space patterns, where the first film is developed using a negative tone imaging process and the second film using a similar but thinner composition, ensuring the first pattern's insolubility in the second resist composition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If double patterning process is used to improve resolution, then resolution is improved, but the first resist pattern is damaged (line width decrease, film thickness reduction)

Engineering Contradiction:

ImproveresolutionVSAvoidpattern shape integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A freezing material layer is introduced as an intermediary between the first and second resist patterns. This layer acts as a protective mediator that prevents the second patterning process from damaging the first pattern, thereby maintaining pattern shape integrity while enabling higher resolution through double patterning

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The freezing material is applied in advance before the second patterning process. This preliminary action creates a protective barrier that prevents subsequent etching or modification of the first pattern during the second exposure and development steps

Inventive Principle:

Principle #10Preliminary action

2Reliability

If freezing material is used to protect the first resist pattern, then pattern shape is maintained, but throughput decreases

Engineering Contradiction:

Improvepattern shape integrityVSAvoidthroughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The resist composition is designed to serve multiple functions: it forms the resist pattern itself and simultaneously acts as a freezing material that protects underlying patterns. This multi-functionality eliminates the need for a separate freezing material layer, thereby maintaining throughput while preserving pattern integrity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If positive developing process is used, then structure of photomask is simplified and contrast is improved, but trench pattern and hole pattern are hard to form

Engineering Contradiction:

Improvephotomask structure simplicityVSAvoidtrench and hole pattern formation

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention inverts the conventional approach by using negative tone imaging instead of positive developing. This inversion enables effective formation of trench and hole patterns while maintaining process simplicity, as the negative tone resist retains material in exposed regions rather than removing it

Inventive Principle:

Principle #13The other way round (Inversion)

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

This method effectively forms ultrafine line and space patterns with improved resolution and reduced pattern damage by maintaining the shape of the first negative pattern and enhancing the insolubility in the second resist composition, overcoming the limitations of existing techniques in achieving high-resolution trench and hole patterns.

Implementation Method 1

actinic ray-sensitive or radiation-sensitive resin composition

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

resin of which solubility in a developer containing an organic solvent decreases due to polarity increased by an action of an acid

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Implementation Method 3

two-stage patterning with heating processes

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS9885956B2Pattern forming method, and, electronic device producing method and electronic device, each using the same

Publication Date: 2018.02.06 FUJIFILM CORP

AI summary

A pattern forming method includes: (a) forming a first film on a substrate using an actinic ray-sensitive or radiation-sensitive resin composition (I) containing a resin of which solubility in a developer containing an organic solvent decreases due to polarity increased by an action of an acid; (b) exposing the first film; (c) developing the exposed first film using a developer containing an organic solvent to form a first negative pattern; (e) forming a second film on the substrate using an actinic ray-sensitive or radiation-sensitive resin composition (II) containing a resin of which solubility in a developer containing an organic solvent decreases due to polarity increased by an action of an acid; (f) exposing the second film; and (g) developing the exposed second film using a developer containing an organic solvent to form a second negative pattern in this order.