Photoresist Underlayer Acid Diffusion for Pattern Quality

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In semiconductor IC device manufacturing, the scaling down process leads to incomplete development of the photoresist layer during photolithography, resulting in unwanted variations in line width roughness and local critical dimension uniformity, which reduces production yield due to residual photoresist residue and incomplete pattern transfer.

Innovation Solution

The use of a multi-layer structure with a bottom layer containing acid generators and a photoresist layer where acid from the underlayer diffuses into the photoresist, enhancing solubility and uniformity, thereby reducing residual photoresist and improving pattern quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-layer photoresist structure is used, then the process is simple, but incomplete development occurs leading to residual photoresist and poor pattern quality

Engineering Contradiction:

Improveprocess simplicityVSAvoidpattern quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The photoresist system is divided into two distinct layers: a bottom layer containing acid generators and a photoresist layer. This segmentation allows each layer to perform specific functions - the bottom layer generates acid that diffuses upward to modify the photoresist layer, enabling complete development while maintaining processability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite multi-layer structure combining materials with different properties - the bottom layer contains acid generators (such as photoacid generators or thermal acid generators) while the photoresist layer contains polymers with specific solubility characteristics. This composite structure enables both complete development and good pattern quality

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If photoresist is exposed to light for complete pattern transfer, then pattern transfer is improved, but line width roughness and critical dimension uniformity deteriorate due to residual photoresist

Engineering Contradiction:

Improvepattern transfer completenessVSAvoidline width roughness and critical dimension uniformity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The bottom layer is prepared in advance with acid generators that will diffuse into the photoresist layer during exposure or post-exposure baking. This preliminary preparation ensures that the photoresist layer becomes sufficiently modified to allow complete development without residual photoresist, while maintaining uniform critical dimensions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Acid acts as an intermediary that diffuses from the bottom layer into the photoresist layer, mediating the interaction between the two layers. This acid diffusion modifies the photoresist to enable complete development while preventing the harmful effects of residual photoresist on line width roughness and critical dimension uniformity

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

This approach improves the quality of patterns transferred during lithography patterning by reducing residual photoresist and variations in line width roughness and local critical dimension uniformity, increasing production yield.

Implementation Method 1

acid from the underlayer diffuses into the photoresist

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20230146910A1Methods and compositions for improved patterning of photoresist

Publication Date: 2023.05.11 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Disclosed methods employ acid generator components in an underlayer. Acid generated by the acid generator components diffuses into an overlying layer, e.g., a photoresist layer, and provides acid which chemically alters the photoresist, e.g., alters the solubility of the photoresist in a developer solution. The acid that diffuses into the overlying photoresist layer increases the concentration and the uniformity of concentration of the acid in lower portions of the photoresist. The regions of increased acid concentration within the photoresist can increase the photoresists solubility in developer solutions, thereby reducing inadequate development of the photoresist. Reducing inadequate development of the photoresist can reduce the amount of photoresist residue or scum that remains after development is complete.