Photoresist Surface Treatment and Cap Layer for Pattern Stability

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Solution Overview

Problem

As semiconductor devices shrink in size, photolithographic processing faces tighter process windows, with metal-containing photoresists experiencing moisture and oxygen absorption, leading to degraded pattern resolution and contamination issues.

Innovation Solution

Surface treatment of the photoresist layer to convert hydrophilic ligand end groups to hydrophobic groups, and/or applying a cap layer over the photoresist layer to protect it from ambient moisture and oxygen, thereby stabilizing the photoresist layer and reducing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If metal-containing photoresist is used for photolithographic processing, then lithography performance is improved, but moisture and oxygen absorption occurs leading to pattern resolution degradation

Engineering Contradiction:

Improvepattern resolutionVSAvoidphotoresist stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A cap layer is introduced as an intermediary between the metal-containing photoresist and the ambient environment. This cap layer acts as a protective barrier that mediates the interaction between the photoresist and moisture/oxygen, preventing harmful absorption while allowing the photoresist to maintain its lithography performance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cap layer creates an inert protective environment over the photoresist surface, isolating it from the reactive ambient atmosphere containing moisture and oxygen. This inert barrier prevents chemical interactions that would otherwise degrade the photoresist and compromise pattern resolution

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If photoresist layer is exposed to ambient environment, then processing is simplified, but contamination and defect formation increase

Engineering Contradiction:

Improveprocessing simplicityVSAvoidcontamination and defects

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The cap layer serves as a protective intermediary that allows the photoresist to be handled and processed in the ambient environment without direct harmful interactions. It mediates between the need for ambient processing and the risk of contamination, enabling simplified manufacturing while preventing defect formation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cap layer is applied beforehand to cushion and protect the photoresist from ambient contamination before processing begins. This preemptive protective measure prevents contamination and defect formation during subsequent handling and processing steps

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Area of moving object

If device size is reduced to meet consumer demand, then device density increases, but process windows for photolithographic processing become tighter

Engineering Contradiction:

Improvedevice sizeVSAvoidprocess window

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

The cap layer acts as a disposable protective element that is applied to maintain photoresist stability during processing. While it adds a step, it enables the use of metal-containing photoresists that provide the necessary lithography performance for reduced device sizes, effectively extending the process window

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 surface treatment and cap layer improve developer dispersion, reducing scum and bridge defects, and enhance lithography performance by preventing moisture and oxygen absorption, thus maintaining the ability to scale down semiconductor components.

Implementation Method 1

surface treatment of the photoresist layer to convert hydrophilic ligand end groups to hydrophobic groups

Methodology Applied

Scientific EffectHydrophobe: Hydrophobe

Implementation Method 2

applying a cap layer over the photoresist layer to protect it from ambient moisture and oxygen

Methodology Applied

Scientific EffectAbsorption (physical): Absorption (physical)

Data Source

PatentUS12463034B2Photoresist layer surface treatment, cap layer, and method of forming photoresist pattern

Publication Date: 2025.11.04 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of forming a pattern in a photoresist layer includes forming a photoresist layer over a substrate, and reducing moisture or oxygen absorption characteristics of the photoresist layer. The photoresist layer is selectively exposed to actinic radiation to form a latent pattern, and the latent pattern is developed by applying a developer to the selectively exposed photoresist layer to form a pattern.