Optical Emission Spectrometry for Plasma Unconfinement Detection

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Solution Overview

Problem

Current methods for cleaning the edge region of wafers are unreliable due to manual control and the challenge of preventing corrosive plasma from affecting integrated circuits, especially as feature sizes shrink and edge exclusion zones become smaller.

Innovation Solution

A method using optical emission spectrometry to monitor wavelength intensity during bevel edge cleaning, terminating the process if deviation exceeds a target, ensuring plasma confinement and protecting integrated circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual visual inspection is used to monitor plasma confinement, then operator control is maintained, but reliability of monitoring is poor

Engineering Contradiction:

Improvereliability of plasma confinement monitoringVSAvoidautomation of monitoring process

Core Design Contradiction:

ReliabilityVSExtent of automation

Solution Approach 1:

The patent replaces manual visual inspection with an optical emission spectrometry system that automatically monitors plasma confinement. The system uses optical sensors to detect wavelength intensities and a controller to process signals, substituting human operators with automated optical detection and control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control system where the optical emission spectrometry continuously monitors plasma confinement status, and the controller automatically terminates the cleaning process when plasma unconfinement is detected. This closed-loop feedback ensures reliable monitoring and automatic response to plasma instability.

Inventive Principle:

Principle #23Feedback

2Productivity

If plasma is used to clean the bevel edge, then cleaning effectiveness is improved, but risk of plasma unconfinement affecting integrated circuits increases

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidharmful effect of plasma unconfinement on integrated circuits

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses optical emission spectrometry to provide real-time feedback on plasma confinement status during the cleaning process. When plasma unconfinement is detected through wavelength intensity monitoring, the system automatically terminates the process, preventing harmful effects on integrated circuits while maintaining cleaning effectiveness.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent implements preliminary monitoring of plasma confinement before damage can occur. By continuously tracking wavelength intensities associated with cleaning byproducts, the system detects plasma unconfinement early and terminates the process in advance, preventing harmful effects on the integrated circuits.

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If feature sizes are reduced, then manufacturing precision is improved, but difficulty of edge cleaning increases

Engineering Contradiction:

Improvefeature size precisionVSAvoidcomplexity of edge cleaning process

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex manual monitoring and control procedures with an automated optical emission spectrometry system. This substitution simplifies the edge cleaning process by providing automatic detection of plasma confinement status and automated process termination, reducing operational complexity despite smaller feature sizes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Provides reliable monitoring and prevention of plasma unconfinement, ensuring effective cleaning of the edge region without damaging the center of the wafer, enhancing the precision and reliability of the cleaning process.

Implementation Method 1

monitoring the selected wavelengths during the cleaning for deviation from a wavelength intensity

Methodology Applied

Scientific EffectOptical emission spectrometry: Absorption Spectroscopy

Implementation Method 2

striking a plasma confined to the peripheral edge region of the substrate

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS8852384B2Method and apparatus for detecting plasma unconfinement

Publication Date: 2014.10.07 LAM RES CORP

AI summary

A method for detecting plasma unconfinement in a reaction chamber during a bevel edge cleaning operation is provided. The method initiates with selecting a wavelength associated with expected by products of a bevel edge clean process. The method includes cleaning the bevel edge area of a substrate and monitoring the intensity of the selected wavelengths during the cleaning for deviation from a threshold wavelength intensity. The cleaning is terminated if the deviation from the threshold wavelength intensity exceeds a target deviation.