Sub-Resolution Mask Patterning for FinFET End-Cutting Precision

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current lithography techniques are limited in forming fin-like field effect transistor (FinFET) devices with smaller dimensions due to resolution constraints, leading to issues with uniform end-cutting and corner rounding of fins.

Innovation Solution

The use of a unique mask set with sub-resolution features and specific patterning methods, including the formation of elongated protrusions and patterned layers, allows for improved lithography resolution by interconnecting pattern areas through intersection areas, reducing corner rounding and ragged ends of fins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional lithography techniques are used to form FinFET devices with small dimensions, then the fabrication process remains simple, but the manufacturing precision and uniformity of fin end-cutting deteriorate due to resolution limits

Engineering Contradiction:

Improvefin end-cutting uniformityVSAvoidpatterning process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patterning process is divided into multiple stages: first forming elongated protrusions with initial lithography, then performing a second patterning step with end-cutting masks to define precise fin end positions. This segmentation allows each step to optimize for its specific function, achieving high precision without requiring the entire process to exceed lithography resolution limits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces sub-resolution features (such as mandrels or spacers) that extend beyond the immediate fin region in the lateral dimension. These features act as etch-stop structures that define fin end positions indirectly, allowing precision control of fin ends without requiring the lithography system to directly resolve the fin end geometry itself.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If lithography resolution limits are accepted, then the exposure tool remains simple and cost-effective, but the manufacturing precision of sub-10nm fin structures deteriorates

Engineering Contradiction:

Improvefin pattern accuracyVSAvoidlithography resolution

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

Sub-resolution mandrels or spacer structures serve as intermediary elements between the lithography system and the final fin structure. These intermediaries are formed at a larger scale that the lithography tool can resolve, then used as templates or etch-stop references to define the precise positions of sub-10nm fin features, effectively decoupling the lithography resolution requirement from the final feature size precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The method performs preliminary patterning to form elongated protrusions and sub-resolution reference features before the final fin formation step. This preliminary action establishes a framework of etch-stop structures that guide subsequent self-aligned etching processes, ensuring high precision fin patterning without requiring the lithography tool to directly pattern the final fin dimensions.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If end-cutting masks with sub-resolution features are used, then the fin end-cutting uniformity improves, but the mask complexity and fabrication cost increase

Engineering Contradiction:

Improvecorner rounding reductionVSAvoidmask fabrication ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The end-cutting masks incorporate sub-resolution features (such as assist mandrels or spacer-defined regions) only at critical locations where fin end precision is required, rather than across the entire mask area. This local application of enhanced complexity allows corner rounding control and fin end uniformity improvement while minimizing the overall mask fabrication burden and cost 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 enhances the precision of fin patterning, resulting in more uniform and correctly aligned ends of fins, overcoming the limitations of existing lithography techniques in FinFET device fabrication.

Implementation Method 1

an exposure tool passes light through a mask or reticle and focuses the light onto a resist layer of a wafer, resulting in the resist layer having an image of integrated circuit components therein

Methodology Applied

Scientific EffectPhotolithography: Photography

Implementation Method 2

The method further includes cutting ends of the elongated protrusions using the pattern on the first layer

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS9904163B2Cut-mask patterning process for FIN-like field effect transistor (FINFET) device

Publication Date: 2018.02.27 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Disclosed is a mask for use in a lithography system having a defined resolution. The mask comprises first and second patterns that are greater than the defined resolution and a sub-resolution feature that is less than the defined resolution. Portions of the first and second patterns are positioned close to each other and separated by the sub-resolution feature in an intersection area. The size and shape of the sub-resolution feature are such that when the mask is used in the lithography system, a resulting pattern includes the first and second patterns interconnected with each other through the interconnection area.