FinFET Line Edge Roughness Analysis via Atomic Force Microscopy

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Solution Overview

Problem

The decreasing scaling in semiconductor technology poses challenges in maintaining line edge roughness within desired ranges for FinFET devices, affecting transistor performance, as existing measurement techniques struggle to accurately assess and correct fin structure roughness.

Innovation Solution

A system and method utilizing a scanning probe microscope with oscillating probe tips to scan and analyze the surface characteristics of FinFET devices, employing power spectral density analysis to extract line edge roughness, allowing for sub-nanometer resolution imaging and refinement of the fin fabrication process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional surface measurement techniques are used to measure fin structure roughness, then measurement capability is provided, but measurement precision is insufficient for sub-nanometer scale roughness assessment

Engineering Contradiction:

Improveline edge roughness measurement precisionVSAvoidfin structure line edge roughness

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent replaces conventional optical/mechanical surface measurement techniques with atomic force microscopy (AFM), which uses a physical probe to scan the surface and detect atomic-level variations through force interactions. This substitution enables sub-nanometer measurement precision for line edge roughness, directly resolving the contradiction between measurement precision and manufacturing precision requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If scaling is decreased to increase device density, then device density increases, but line edge roughness control becomes more difficult

Engineering Contradiction:

Improvedevice densityVSAvoidline edge roughness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism where AFM measurements of line edge roughness are obtained with sub-nanometer precision, analyzed to determine roughness characteristics, and used to adjust fabrication process parameters. This closed-loop feedback enables continuous improvement and control of line edge roughness even as scaling decreases and device density increases.

Inventive Principle:

Principle #23Feedback

3Difficulty of detecting and measuring

If conventional measurement techniques are used, then measurement process is simple, but the ability to detect and measure sub-nanometer roughness is insufficient

Engineering Contradiction:

Improvesub-nanometer roughness detection capabilityVSAvoidmeasurement system complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent replaces simple conventional measurement systems with atomic force microscopy, which uses a cantilever probe that detects surface topography through atomic force interactions. This mechanical substitution enables sub-nanometer detection capability despite increased system complexity, as the AFM system provides quantitative roughness measurements that conventional techniques cannot achieve.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables precise measurement and correction of line edge roughness, improving transistor performance by reducing undesirable roughness and linewidth variations, thus enhancing the reliability and efficiency of FinFET device fabrication.

Implementation Method 1

a probe tip is employed to scan across the three-dimensional structure... The line edge profile is then analyzed... The vertical oscillation allows the probe tip to reach different depths from the fin top and be in close proximity to the bottom between the adjacent fins

Methodology Applied

Scientific EffectAtomic force microscopy: Scanning Probe Microscopy

Data Source

PatentUS11774241B2Line edge roughness analysis using atomic force microscopy

Publication Date: 2023.10.03 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Embodiments disclosed herein relate generally to methods for measuring a characteristic of a substrate. In an embodiment, the method includes scanning over the substrate with a scanning probe microscope, the substrate having fins thereon, the scanning obtaining images showing respective fin top regions of the fins, the scanning probe microscope interacting with respective portions of sidewalls of the fins by a scanning probe oscillated during the scanning, selecting images obtained at a predetermined depth below the fin top regions to obtain a line edge profile of the fins, by a processor-based system, analyzing the line edge profile of the fins using power spectral density (PSD) method to obtain spatial frequency data of the line edge profile of the fins, and by the processor-based system, calculating line edge roughness of the fins based on the spatial frequency data.