Electromagnetic Circuit for Solid Material Detection in Plasma Exhaust

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Solution Overview

Problem

Conventional ashing processes in semiconductor manufacturing, particularly those using oxygen or nitrogen-based plasma chemistry, can damage low-k dielectric materials and make it difficult to detect the endpoint of photoresist removal due to the lack of light emission in helium-hydrogen plasma reactions, leading to material deposition in processing chambers.

Innovation Solution

A method and system utilizing an electromagnetic circuit to detect solid materials in exhaust gases by exciting the gases with electromagnetic energy and measuring impedance values, which correlates with the amount of solid material present, allowing for effective photoresist removal without damaging low-k dielectric layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If oxygen or nitrogen-based plasma chemistry is used for ashing photoresist, then photoresist removal is effective, but low-k dielectric materials are damaged

Engineering Contradiction:

Improvephotoresist removal efficiencyVSAvoiddamage to low-k dielectric materials

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the plasma gas from conventional oxygen/nitrogen-based chemistry to a fluorocarbon-based chemistry (e.g., CF4, C2F6). This parameter change fundamentally alters the plasma chemistry to achieve photoresist removal through fluorocarbon radical reactions that do not attack low-k dielectric materials, thus resolving the contradiction between removal efficiency and material damage

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates an inert fluorocarbon-based plasma environment that is selective to photoresist materials. The fluorocarbon plasma chemistry is designed to be non-reactive with low-k dielectric materials while effectively removing organic photoresist, effectively creating a chemically inert environment toward the sensitive dielectric layers

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Object-affected harmful factors

If helium-hydrogen plasma is used for photoresist removal, then low-k dielectric materials are protected, but light emission for endpoint detection is absent

Engineering Contradiction:

Improvedamage to low-k dielectric materialsVSAvoidendpoint detection

Core Design Contradiction:

Object-affected harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces a small amount of oxygen into the helium-hydrogen plasma to create a controlled chemical reaction that produces light emission. This allows optical endpoint detection to function while maintaining the protective nature of the helium-hydrogen plasma chemistry toward low-k dielectric materials

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent uses oxygen as an intermediary substance that facilitates light emission for detection purposes without significantly compromising the protective effect of the helium-hydrogen plasma on low-k dielectric materials. The oxygen acts as a mediator to enable optical detection while the dominant helium-hydrogen chemistry continues to protect the sensitive dielectric layers

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If conventional ashing processes are used, then photoresist is removed, but solid material deposits in the processing chamber

Engineering Contradiction:

Improvephotoresist removalVSAvoidmaterial deposition in chamber

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the plasma chemistry parameters from conventional oxygen/nitrogen-based ashing to fluorocarbon-based chemistry, which alters the byproduct formation and reduces solid material deposition in the processing chamber while maintaining effective photoresist removal

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional thermal/volatilization-based ashing mechanism with a chemically-driven fluorocarbon plasma mechanism that removes photoresist through selective chemical reactions, thereby reducing the formation of solid particulate byproducts that would otherwise deposit in the chamber

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

This approach enables accurate detection of solid materials in exhaust gases, preventing material deposition and ensuring efficient photoresist removal while maintaining the integrity of low-k dielectric layers, thereby improving the ashing process in semiconductor manufacturing.

Implementation Method 1

exciting the medium of interest using electromagnetic energy, and determining an impedance value of the electromagnetic circuit

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS7794663B2Method and system for detection of solid materials in a plasma using an electromagnetic circuit

Publication Date: 2010.09.14 LAM RES CORP

AI summary

A method for solid material detection in a medium includes receiving an exhaust gas downstream with respect to a workpiece from which a photoresist material is removed. An electromagnetic circuit is configured to include the exhaust gas, the exhaust gas is excited with electromagnetic energy and an impedance value of the electromagnetic circuit is determined, wherein the impedance value corresponds to an amount of solid material within the exhaust gas.