Lithography Metrology Allocation for Precision and Throughput

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Solution Overview

Problem

Current lithography systems face challenges in handling increasing complexity and smaller printing nodes with growing metrology inputs while meeting shrinking printing time requirements, often resulting in reduced sampling and larger errors.

Innovation Solution

The integration of a monitoring channel between an integrated metrology tool and a standalone metrology tool allows for optimized metrology measurement allocation and monitoring within specified temporal limitations, enabling improved process control, recipe optimization, and landscape-based grouping of process parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If metrology measurements are increased to handle growing complexity and smaller printing nodes, then measurement precision is improved, but printing time increases and productivity deteriorates

Engineering Contradiction:

Improvemetrology measurement precisionVSAvoidprinting time

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent divides metrology measurements into two segments: critical dimension (CD) measurements performed by an integrated metrology tool during printing, and overlay measurements performed by a standalone metrology tool. This segmentation allows CD measurements to be done in-line without stopping printing, while overlay measurements are performed separately on selected wafers, thus maintaining printing productivity while ensuring measurement precision for both parameters

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary allocation of metrology measurements before printing begins. The integrated metrology tool is configured to perform CD measurements on all wafers during the printing process, and the standalone metrology tool is configured to perform overlay measurements on a subset of wafers. This preliminary arrangement ensures that measurement requirements are met without causing delays during actual printing operations

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If comprehensive metrology measurements are performed on all wafers, then measurement precision is improved, but device complexity and operational complexity increase

Engineering Contradiction:

Improvemetrology measurement completenessVSAvoidmetrology system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The integrated metrology tool is designed to perform multiple functions: it conducts critical dimension measurements on all wafers during the printing process and also provides overlay measurements for wafers selected by the allocation algorithm. This multi-functionality reduces the need for separate dedicated tools for each measurement type, thereby managing system complexity while maintaining comprehensive measurement coverage

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses its own integrated metrology tool to perform CD measurements on all wafers during normal printing operations, serving its own measurement needs without requiring external intervention. The standalone metrology tool supplements this by performing overlay measurements on selected wafers, creating a self-sufficient measurement system that handles both CD and overlay requirements

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If more metrology measurements are performed, then manufacturing precision is improved, but loss of time increases due to reduced sampling rate

Engineering Contradiction:

Improveprocess control accuracyVSAvoidmetrology cycle time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The integrated metrology tool performs CD measurements continuously on all wafers during the printing process without interrupting production flow. This continuous measurement approach ensures that manufacturing precision is maintained for critical dimensions while avoiding the time loss associated with stopping printing operations for separate measurement cycles

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system performs full CD measurements on all wafers (excessive action for completeness) while performing overlay measurements only on a selected subset of wafers (partial action). This selective approach ensures that manufacturing precision is maintained for critical parameters without requiring exhaustive measurement of all possible parameters on every wafer, thus reducing overall measurement cycle time

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10331050B2Lithography systems with integrated metrology tools having enhanced functionalities

Publication Date: 2019.06.25 KLA CORP

AI summary

Lithography systems and methods are provided with enhanced performance based on broader utilization of the integrated metrology tool in the printing tool to handle the metrology measurements in the system in a more sophisticated and optimized way. Additional operation channels are disclosed, enabling the integrated metrology tool to monitor and/or allocate metrology measurements thereby and by a standalone metrology tool with respect to specified temporal limitations of the printing tool; to adjust and optimize the metrology measurement recipes; to provide better process control to optimize process parameters of the printing tool; as well as to group process parameters of the printing tool according to a metrology measurements landscape.