Critical Dimension Measurement Using Optical Reference Patterns

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current methods for measuring critical dimensions of photoresist patterns in semiconductor fabrication are time-consuming, especially when relying on optic modeling and simulations, and may not ensure uniformity of patterns, affecting the reliability of semiconductor devices.

Innovation Solution

A method involving the formation of reference patterns with different critical dimensions on a substrate, where the optical properties are measured using a spectrophotometer, allowing for rapid and accurate determination of the critical dimension of an object pattern by comparing its optical properties with those of the reference patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optic modeling and simulations are used to measure critical dimensions, then measurement precision is improved, but measurement time increases significantly

Engineering Contradiction:

Improvecritical dimension measurement precisionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates optical properties (reflectivity and transmittance) for multiple known critical dimension values before actual measurement. These pre-computed reference values are stored and used during measurement to eliminate the need for repeated simulations, thus reducing measurement time while maintaining precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a lookup table containing pre-computed optical properties corresponding to various critical dimension values. During measurement, the system copies the measured optical property value to find the matching critical dimension from the table, avoiding time-consuming real-time simulations.

Inventive Principle:

Principle #26Copying

2Measurement precision

If repeated simulations are performed to match measured optical properties, then measurement accuracy is improved, but productivity decreases

Engineering Contradiction:

Improvecritical dimension measurement accuracyVSAvoidmeasurement throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system performs the computationally intensive simulation work in advance, generating a comprehensive lookup table of optical properties for various critical dimension values. This preliminary computation enables rapid measurements without repeated simulations, thereby improving productivity while maintaining measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical process of repeated simulations with an optical lookup approach. Instead of performing time-consuming computational simulations during measurement, the system uses pre-computed optical property data to quickly determine critical dimensions, significantly improving throughput.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If critical dimensions are measured from the entire semiconductor substrate, then comprehensive coverage is improved, but measurement time increases

Engineering Contradiction:

Improvepattern uniformity coverageVSAvoidsubstrate measurement time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent extracts and measures only the critical region containing the photoresist pattern rather than measuring the entire semiconductor substrate. This selective measurement approach maintains comprehensive coverage of the critical features while significantly reducing measurement time by excluding non-critical areas.

Inventive Principle:

Principle #2Taking out (Extraction)

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 enables rapid and accurate measurement of critical dimensions, improving the uniformity and reliability of photoresist patterns, thereby enhancing the manufacturing process efficiency and device performance.

Implementation Method 1

measuring an optical property of each of the plurality of reference patterns and measuring an optical property of the object pattern may include measuring the optical properties using a spectrophotometer

Methodology Applied

Scientific EffectReflectivity measurement: Reflection

Implementation Method 2

Methodology Applied

Scientific EffectTransmittance measurement: Absorption (EM radiation)

Implementation Method 3

A scatterometer uses a diffraction phenomenon generated when projected light is reflected on a material

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS7803506B2Methods of measuring critical dimensions and related devices

Publication Date: 2010.09.28 SAMSUNG ELECTRONICS CO LTD

AI summary

A method of measuring a critical dimension may include forming an object pattern on a substrate and forming a plurality of reference patterns on the substrate, wherein each of the plurality of reference patterns has a different critical dimension. An optical property of each of the plurality of reference patterns may be measured to provide a respective measured optical property for each of the reference patterns, and an optical property of the object pattern may be measured to provide a measured optical property of the object pattern. The measured optical property of the object pattern may be compared with the measured optical properties of the reference patterns, and a critical dimension of the object pattern may be determined as being the same as the critical dimension of the reference pattern having the measured optical property that is closest to the measured optical property of the object pattern. Related devices are also discussed.