Best Focus and Dose Determination via Process Window Area Comparison

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Solution Overview

Problem

In the semiconductor industry, determining the best focus and dose for forming finer patterns in high-integration semiconductor devices is challenging due to the critical dimension (CD) reduction, which affects the process window and pattern formation accuracy.

Innovation Solution

A method involving selecting split patterns on a wafer, measuring critical dimension (CD) values, calculating effective CD values, and plotting window calculation diagrams to determine the process window area for each shot region, allowing comparison and identification of the best focus and dose values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the critical dimension (CD) is reduced to increase integration degree, then the integration degree of semiconductor device is improved, but the manufacturing precision and process window are worsened

Engineering Contradiction:

Improveintegration degreeVSAvoidcritical dimension control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The method segments the wafer into multiple shot regions and further divides each shot region into multiple selection patterns. By measuring and calculating CD values for each segmented pattern, the system can determine effective CD values and process window areas for different regions, enabling precise control of critical dimensions even as overall integration degree increases

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method changes the parameter approach by not relying on a fixed target CD value. Instead, it calculates effective CD values based on actual measurements from multiple selection patterns and determines process window areas. This dynamic parameter adjustment allows the system to adapt to CD variations and maintain manufacturing precision despite smaller feature sizes

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the target CD value is not used, then the determination of best focus and dose becomes more flexible, but the measurement precision and reliability are worsened

Engineering Contradiction:

Improvebest focus and dose determination flexibilityVSAvoidCD measurement reliability

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The method merges multiple measurement data from different selection patterns within each shot region. By combining CD measurements from multiple patterns and calculating an effective CD value for each shot region, the system achieves reliable determination of best focus and dose without depending on a single target CD value or single measurement point

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The method changes from using a fixed target CD parameter to using calculated effective CD values derived from actual measurements. This parameter transformation maintains measurement reliability by basing decisions on real empirical data from multiple patterns rather than theoretical target values, while providing flexibility to adapt to actual process conditions

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If multiple selection patterns are measured and processed, then the process window area calculation becomes more accurate, but the device complexity and measurement time are increased

Engineering Contradiction:

Improveprocess window area accuracyVSAvoidmeasurement and calculation complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The method segments the measurement process into hierarchical levels: first dividing the wafer into shot regions, then dividing each shot region into multiple selection patterns. This structured segmentation allows systematic measurement and calculation that improves process window accuracy while maintaining organized complexity that can be managed through automated processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method uses multiple selection patterns (excessive action) to ensure accurate process window calculation, but strategically selects specific patterns within shot regions rather than measuring every possible pattern. This partial measurement approach achieves sufficient accuracy for determining best focus and dose without the full complexity of exhaustive measurement

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS12135504B2Method for determining best focus and best dose in exposure process

Publication Date: 2024.11.05 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for determining a best focus and a best dose in the disclosure includes selecting a selection pattern from first and second shot regions of a wafer for split, measuring a critical dimension (CD) value of the selection pattern, thereby deriving a measurement CD value, calculating an effective CD value of the selection pattern for each of the first and second shot regions using the measurement CD value, calculating an upper-limit CD value and a lower-limit CD value of the selection pattern using the effective CD value of the selection pattern, calculating a process window area for the first shot region and a process window area for the second shot region using the upper-limit CD value and the lower-limit CD value of the selection pattern, and comparing the process window area for the first shot region and the process window area for the second shot region with each other.