Photoresist Thickness Switching to Prevent Pattern Collapse

Solution Overview

Problem

Current semiconductor fabrication methods face challenges in achieving stable and reliable photoresist pattern distribution, particularly in preventing pattern collapse during the photolithography process, especially as feature sizes are reduced.

Innovation Solution

The method involves forming a photoresist layer with an initial thickness of 400 Å or more to improve pattern distribution and then reducing it to a thickness of 250 Å or less through an etch back process to prevent pattern collapse, while maintaining sufficient thickness for etching and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a thicker photoresist layer (400 Å or more) is used, then the distribution of the photoresist pattern is improved, but the photoresist pattern is more likely to collapse

Engineering Contradiction:

Improvephotoresist pattern distributionVSAvoidphotoresist pattern stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by performing an etch back process to reduce the photoresist layer thickness before the development step. This pre-reduction of thickness prevents the high aspect ratio problem that would cause pattern collapse during development, while still maintaining sufficient thickness for proper pattern distribution and etching performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by changing the photoresist layer thickness dynamically at different stages of the process. The layer starts with a greater thickness (400 Å or more) for optimal pattern distribution and etching, then is reduced to a smaller thickness (250 Å or less) before development to prevent collapse, allowing the system to adapt to different process requirements.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If a thinner photoresist layer (600 Å or less) is used, then the photoresist pattern is prevented from collapsing, but the distribution of the photoresist pattern deteriorates

Engineering Contradiction:

Improvephotoresist pattern stabilityVSAvoidphotoresist pattern distribution

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by performing an etch back process to reduce the photoresist layer thickness before the development step. This pre-reduction of thickness prevents the high aspect ratio problem that would cause pattern collapse during development, while still maintaining sufficient thickness for proper pattern distribution and etching.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by changing the photoresist layer thickness dynamically at different stages of the process. The layer starts with a greater thickness (400 Å or more) for optimal pattern distribution and etching, then is reduced to a smaller thickness (250 Å or less) before development to prevent collapse, allowing the system to adapt to different process requirements.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If the photoresist layer thickness is reduced after exposure, then the aspect ratio is reduced and collapse is prevented, but an additional process step is required

Engineering Contradiction:

Improvephotoresist pattern stabilityVSAvoidfabrication process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent merges the etch back process with the existing photolithography fabrication sequence by positioning it between exposure and development. This integration allows the thickness reduction to be accomplished using standard process equipment already present in the fabrication line, minimizing additional complexity while achieving the stability benefit.

Inventive Principle:

Principle #5Merging (Combining)

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 approach enhances the resolution and stability of the photolithography process by reducing the aspect ratio of the photoresist pattern, preventing collapse and improving line width roughness, thereby improving the overall semiconductor device performance.

Implementation Method 1

exposing a portion of the photoresist layer to form an exposed portion and a non-exposed portion of the photoresist layer

Methodology Applied

Scientific EffectPhotolithography: Photography

Implementation Method 2

exposing a portion of the photoresist layer to form an exposed portion and a non-exposed portion of the photoresist layer

Methodology Applied

Scientific EffectPhotochemical reaction: Photo-oxidation

Implementation Method 3

removing part of the photoresist layer to reduce a thickness of the photoresist layer

Methodology Applied

Scientific EffectEtch back: Ablation

Data Source

PatentUS20240023305A1Fabricating semiconductor device

Publication Date: 2024.01.18 SAMSUNG ELECTRONICS CO LTD

AI summary

A method of fabricating a semiconductor device includes forming a photoresist layer on a lower structure to have a first thickness, exposing a portion of the photoresist layer to form an exposed portion and a non-exposed portion of the photoresist layer, removing a part of the photoresist layer to form a photoresist layer having a second thickness that smaller than the first thickness, and removing the exposed portion or the non-exposed portion of the photoresist layer having the second thickness to form a photoresist pattern.