Wafer Reflectance Monitoring for Real-Time Etch Status Detection

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Solution Overview

Problem

Conventional etching process monitoring is inefficient as it requires off-line measurements, leading to delayed identification of process status and potential waste of resources when the etching process fails.

Innovation Solution

A multi-chamber system equipped with an optical reflectometer for real-time measurement of optical reflectance after the etching process, using a multi-wavelength light source to distinguish materials and determine the completeness of etching, thereby immediately identifying the etching process status as pass or fail.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If off-line measurement is performed to monitor etching process status, then measurement can be done after process completion, but process status identification is delayed and resources are wasted when etching fails

Engineering Contradiction:

Improveetching process status identification accuracyVSAvoidtime delay in identifying etching process status

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing reflectance measurement during the etching process before it completes. The measurement is taken at an intermediate stage to predict the final etching result, allowing early identification of pass or fail status. This enables timely intervention and prevents waste of subsequent processing resources on failed wafers.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If conventional off-line measurement method is used, then equipment complexity is low, but productivity is reduced due to delayed status identification

Engineering Contradiction:

Improveetching process monitoring efficiencyVSAvoidmeasurement system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a measurement system that can perform reflectance measurements across multiple wavelengths within a single integrated platform. The system uses a broadband light source and spectrometer combination that can distinguish different materials (silicon dioxide, silicon nitride, metal layers) through their unique spectral signatures, enabling multi-functional material identification and etching status determination.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 immediate monitoring of the etching process status, reducing resource waste and improving accuracy through real-time reflectance measurements, ensuring timely intervention and optimizing process efficiency.

Implementation Method 1

perform real-time measurements of reflectance from the wafer that is carried in the factory interface or the etching tool

Methodology Applied

Scientific EffectOptical reflectance: Reflection

Data Source

PatentUS11756840B2Reflectance measurement system and method thereof

Publication Date: 2023.09.12 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A system includes a factory interface, an etching tool, and at least one measuring device. The factory interface is configured to carry a wafer. The etching tool is coupled to the factory interface and configured to process the wafer transferred from the factory interface. The at least one measuring device is equipped in the factory interface, the etching tool, or the combination thereof. The at least one measuring device is configured to perform real-time measurements of reflectance from the wafer that is carried in the factory interface or the etching tool.