Virtual Metrology Integration in Semiconductor MES

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Solution Overview

Problem

Conventional Statistical Process Control (SPC) systems in semiconductor manufacturing are limited in performing real-time workpiece-to-workpiece (W2W) inspections and require excessive use of test wafers for tool monitoring, leading to increased costs and reduced production efficiency.

Innovation Solution

Integration of a Virtual Metrology System (VMS) into the Manufacturing Execution System (MES) to provide virtual metrology values for real-time W2W inspections and control, allowing for the calculation of virtual metrology values based on process data and actual measurements, enabling real-time quality monitoring and tool health assessment without the need for periodic offline testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional SPC systems use sample workpieces for online monitoring, then monitoring cost is reduced, but measurement precision and reliability of quality assessment deteriorate

Engineering Contradiction:

Improvenumber of test wafersVSAvoidquality assessment accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent creates virtual copies of physical metrology measurements through virtual metrology models. These computational models generate virtual measurement data that replicates the information obtained from physical metrology tools, eliminating the need to send actual workpieces to metrology tools while preserving measurement precision through accurate modeling of the manufacturing process and measurement system.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The system performs preliminary virtual measurements and predictions before actual manufacturing operations complete. By using virtual metrology to predict workpiece quality outcomes based on process data, the system can identify potential quality issues early and adjust process parameters proactively, rather than waiting for physical metrology measurements after processing.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If offline monitoring SPC uses test workpieces for tool monitoring, then tool health assessment is improved, but productivity and manufacturing efficiency deteriorate

Engineering Contradiction:

Improvetool monitoring accuracyVSAvoidproduction cycle time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system replaces physical test workpieces with virtual measurements generated from process data and virtual metrology models. This allows continuous tool monitoring without removing workpieces from the production flow or dedicating separate test workpieces, thereby maintaining productivity while achieving reliable tool health assessment through accurate virtual measurement data.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The virtual metrology system enables continuous quality monitoring and tool assessment during normal production operations rather than requiring periodic offline testing. Process data is continuously collected and fed into virtual metrology models to provide real-time quality predictions and tool performance feedback, eliminating interruptions to the production cycle.

Inventive Principle:

Principle #20Continuity of useful action

3Measurement precision

If physical metrology tools are used for W2W inspection, then measurement precision is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveworkpiece inspection accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces physical metrology tools and their associated complex hardware systems with computational virtual metrology models. Instead of using optical, mechanical, or electron beam-based physical measurement devices, the system uses software-based models that process manufacturing process data to predict workpiece quality, significantly reducing device complexity while maintaining measurement precision through accurate process modeling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If conventional SPC performs monitoring after process completion, then measurement accuracy is maintained, but speed of quality feedback deteriorates

Engineering Contradiction:

Improvequality measurement accuracyVSAvoidquality feedback time

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The virtual metrology system performs quality predictions and measurements virtually during or immediately after processing, before physical metrology would occur. By using process data to predict workpiece quality outcomes in real-time, the system provides immediate quality feedback that can trigger rapid process adjustments, eliminating the time delay inherent in sending workpieces to physical metrology tools after processing completes.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8983644B2Manufacturing execution system with virtual-metrology capabilities and manufacturing system including the same

Publication Date: 2015.03.17 NAT CHENG KUNG UNIV

AI summary

A manufacturing execution system (MES) with virtual-metrology capabilities and a manufacturing system including the MES are provided. The MES is built on a middleware architecture (such as an object request broker architecture), and includes an equipment manager, a virtual metrology system (VMS), a statistical process control (SPC) system, an alarm manager and a scheduler. The manufacturing system includes a first process tool, a second process tool, a metrology tool, the aforementioned MES, a first R2R (Run-to-Run) controller and a second R2R controller.