Lithographic Mask Layer Line Edge Roughness Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods fail to adequately reduce line edge roughness (LER) and line width roughness (LWR) for sub-20 nm lines in lithographic mask layers, which affects the electrical properties of devices and hinders the adoption of extreme ultraviolet lithography (EUVL) at advanced technology nodes.

Innovation Solution

A method involving the infiltration of a patterned organic material layer with a metal or ceramic material, followed by oxidative plasma etching, to form a denser framework with improved LER and LWR, and enhanced etch resistance, using sequential infiltration synthesis (SIS) and oxidative plasma processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If lithographic mask layers are scaled to sub-20 nm line widths, then device density and integration are improved, but line edge roughness and line width roughness increase significantly

Engineering Contradiction:

Improveline widthVSAvoidline edge roughness

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies sequential infiltration synthesis to gradually change the density and composition parameters of the resist material. By controlling the infiltration process to achieve partial densification (15-85% of intrinsic density), the method transforms the physical state of the resist material to reduce roughness while maintaining sub-20 nm line widths

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by infiltrating metal or ceramic materials into the organic resist material. This composite approach combines the patterning capability of organic photoresists with the structural stability and low roughness of inorganic materials, achieving both small feature sizes and high manufacturing precision

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If additional treatment steps are applied after pattern formation to reduce roughness, then line characteristics are improved, but process complexity and manufacturing time increase

Engineering Contradiction:

Improveline width roughnessVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent performs the infiltration and densification treatment before the etching step, rather than after pattern formation. This preliminary action prepares the resist material with improved mechanical properties and reduced roughness before it is needed for pattern transfer, avoiding additional post-processing steps

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines multiple functions into the infiltration process: it simultaneously densifies the resist material, reduces line edge roughness, and enhances etch resistance. This merging of functions achieves multiple improvements through a single integrated process rather than separate sequential steps

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If metal or ceramic material is infiltrated at high density, then etch resistance is improved, but line width roughness may increase due to material stress

Engineering Contradiction:

Improveetch resistanceVSAvoidline width roughness

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent applies partial infiltration, leaving the metal or ceramic material at 15-85% of its intrinsic density rather than full density. This partial action provides sufficient etch resistance while avoiding the excessive stress and roughness that would result from complete densification

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent creates local quality variations within the infiltrated material, with different regions having different densities and compositions. The top portion may have higher infiltration than lower regions, optimizing both etch resistance and mechanical stability to prevent roughness increase

Inventive Principle:

Principle #3Local quality

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 significantly reduces LER and LWR, leading to improved device uniformity and electrical properties, allowing for more precise and reliable pattern transfer and scaling down of line widths beyond previous limits.

Implementation Method 1

infiltrating at least a top portion of the first set of lines with a metal or ceramic material

Methodology Applied

Scientific EffectSequential infiltration synthesis: Chemical Vapour Deposition

Implementation Method 2

removing the organic material by oxidative plasma etching

Methodology Applied

Scientific EffectOxidative plasma etching: Oxidation

Data Source

PatentUS10824078B2Lithographic mask layer

Publication Date: 2020.11.03 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

An example embodiment relates to a method for making a mask layer. The method may include providing a patterned layer on a substrate, the patterned layer including at least a first set of lines of an organic material of a first nature, the lines having a line height, a first line width roughness, and being separated either by voids or by a material of a second nature. The method may further include infiltrating at least a top portion of the first set of lines with a metal or ceramic material. The method may further include removing the organic material by oxidative plasma etching, thereby forming a second set of lines of metal or ceramic material on the substrate, the second set of lines having a second line width roughness, smaller than the first line width roughness.