Multi-Patterning Mask Width Tuning for Sub-10 Nm Lithography

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Solution Overview

Problem

The etch resistance of resist layers in photolithography processes is inadequate for achieving the required feature sizes in advanced integrated circuits, necessitating the use of hardmasks and multi-patterning techniques to maintain resolution and precision.

Innovation Solution

A multi-patterning technique involving multiple masks is employed, where each mask is formed sequentially over the substrate, with independent adjustment of line widths using area selective processes to form a combined etch mask that transfers the desired pattern to the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If photolithography with shorter wavelength light source is used to achieve higher resolution, then manufacturing precision is improved, but device complexity increases due to multiple patterning steps

Engineering Contradiction:

Improvefeature size resolutionVSAvoidpatterning process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patterning process is divided into multiple sequential steps, each creating a portion of the final pattern. Multiple masks are formed and processed independently, with each mask contributing specific features to the final etch mask pattern, enabling complex patterns to be built incrementally

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from planar single-layer patterning to multi-layer stacked mask architecture. By adding the vertical dimension with multiple mask layers at different heights, the system achieves higher resolution patterns that cannot be obtained with single-layer photolithography alone

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If resist layer thickness is reduced to achieve smaller features, then manufacturing precision is improved, but etch resistance deteriorates

Engineering Contradiction:

Improvefeature sizeVSAvoidetch resistance

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The etch mask is constructed as a composite structure combining multiple mask layers with different materials and properties. The stacked configuration of different resist and hardmask materials provides both the resolution of thin resists and the etch resistance of harder materials, compensating for the reduced etch resistance of thinner resist layers

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Multiple mask layers are nested vertically in a stacked configuration, with each layer contained within the structure of the others. This nested arrangement allows thinner resist layers to provide high-resolution patterning while being supported by underlying or overlying hardmask layers that provide the necessary etch resistance

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS20250306463A1Patterning a substrate using a multi-patterning technique

Publication Date: 2025.10.02 TOKYO ELECTRON LTD

AI summary

A method for patterning a substrate, the method includes forming a first mask over the substrate, the first mask including first features and first spaces and exposing the substrate at a bottom of each first space; forming a second mask while retaining the first features, the second mask including second features and second spaces, the second features covering a portion of the substrate exposed by the first spaces; and either selectively depositing on or selectively removing material from the second features relative to the first features to change a width of each of the second features.