Protective Photoresist Layering for Precise Lithography Patterns

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Solution Overview

Problem

As semiconductor devices shrink in size, photolithographic processes face tighter process windows due to light scattering, leading to photoresist degradation and pattern defects from exposure radiation leakage into unexposed areas, necessitating advancements in photolithographic processing to maintain the ability to scale down components.

Innovation Solution

A method involving the use of a protective layer and selective exposure to ultraviolet radiation, followed by post-exposure baking and development, to create chemical differences in solubility between exposed and unexposed regions of the photoresist, allowing for precise pattern formation and transfer to the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If photolithographic processing is used to pattern photoresist, then pattern formation is achieved, but light scattering causes exposure radiation to leak into unexposed areas leading to photoresist degradation and pattern defects

Engineering Contradiction:

Improvepattern precisionVSAvoidphotoresist degradation from exposure radiation leakage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

A protective layer is introduced as an intermediary between the photoresist layer and the exposure radiation source. This protective layer absorbs or blocks scattered exposure radiation before it reaches the photoresist, preventing photoresist degradation in unexposed areas while allowing the photolithographic patterning process to proceed effectively

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is applied beforehand to counteract the harmful effect of scattered exposure radiation. By establishing this protective barrier prior to exposure, the system preemptively neutralizes the light scattering problem that would otherwise cause pattern defects and photoresist degradation

Inventive Principle:

Principle #9Preliminary anti-action

2Length of moving object

If pattern pitch is decreased to enable device miniaturization, then device size is reduced, but process windows become tighter making pattern formation more difficult

Engineering Contradiction:

Improvedevice sizeVSAvoidprocess window tolerance

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The introduction of the protective layer changes the optical parameters of the photolithographic system by adding an additional layer with specific optical properties (absorption coefficient, thickness). This parameter change allows for tighter process windows to be maintained even at smaller pattern pitches by compensating for light scattering effects

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If exposure radiation is increased to improve pattern definition, then pattern contrast is enhanced, but more radiation leaks into unexposed areas causing greater photoresist degradation

Engineering Contradiction:

Improvepattern definitionVSAvoidphotoresist degradation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The protective layer serves as a mediator that allows high-intensity exposure radiation to be used for improved pattern definition while simultaneously blocking the scattered radiation that would otherwise cause photoresist degradation. This enables the system to benefit from higher exposure doses without suffering from the associated light scattering problems

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enhances the ability to form precise patterns in photoresist layers, reducing defects and improving the transfer of patterns to substrates, thereby supporting the continued miniaturization of semiconductor devices.

Implementation Method 1

A photoresist layer is formed on the substrate. A protective layer is formed over the photoresist layer. A latent pattern is formed in the photoresist layer by selectively exposing the photoresist layer to actinic radiation

Methodology Applied

Scientific EffectPhotolysis: Photodissociation

Implementation Method 2

A protective layer including a polymer and a basic quencher is formed over the photoresist layer

Methodology Applied

Scientific EffectAcid-base neutralization:

Implementation Method 3

The substrate is heated after the latent pattern is formed in the photoresist layer

Methodology Applied

Scientific EffectThermal energy transfer: Heating

Implementation Method 4

The photoresist layer is developed to form a pattern in the photoresist layer

Methodology Applied

Scientific EffectDifferential solubility:

Data Source

PatentUS12547075B2Method of forming photoresist pattern

Publication Date: 2026.02.10 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of forming a photoresist pattern includes forming a protective layer over a photoresist layer formed on a substrate. The protective layer and the photoresist layer are selectively exposed to actinic radiation. The photoresist layer is developed to form a pattern in the photoresist layer. The protective layer includes a polymer without a nitrogen-containing moiety, and a basic quencher, an organic acid, a photoacid generator, or a thermal acid generator.