TMAH Solution Oxygen Control via Feedback Loop

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Solution Overview

Problem

Existing substrate processing systems face challenges in maintaining stable processing ability and uniformity of chemical liquids, particularly TMAH-containing solutions, due to variations in dissolved oxygen concentrations, which affect etching rates and overall processing consistency.

Innovation Solution

A chemical liquid preparation method and unit that dynamically adjusts the dissolved oxygen concentration in TMAH-containing solutions by switching between nitrogen and oxygen gas supply based on measured oxygen levels, using a feedback loop to maintain optimal oxygen concentrations, thereby stabilizing the processing ability of the chemical liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If nitrogen gas is supplied into the chemical liquid tank to prevent oxygen dissolution, then oxidation of substrate is prevented, but processing ability of the chemical liquid decreases

Engineering Contradiction:

Improveoxidation of substrateVSAvoidprocessing ability

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameter of the chemical liquid by adding alcohol to modify how oxygen interacts with the TMAH solution. This allows oxygen to be present without causing harmful oxidation while maintaining processing ability, resolving the contradiction between preventing oxidation and maintaining productivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Alcohol acts as an intermediary substance that mediates between oxygen and TMAH. It prevents the harmful interaction between oxygen and substrate while allowing oxygen to remain dissolved, thus preventing oxidation without reducing processing ability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If deaeration is performed to decrease dissolved oxygen amount, then substrate oxidation is prevented, but processing ability becomes unstable

Engineering Contradiction:

Improvesubstrate oxidationVSAvoidprocessing ability stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical liquid composition by adding alcohol, which changes the dissolution characteristics of oxygen. This allows the system to maintain stable processing ability while controlling oxygen's harmful effects without requiring continuous deaeration

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback control system that monitors dissolved oxygen concentration and adjusts gas supply accordingly. When oxygen exceeds a threshold, nitrogen or alcohol is supplied to reduce it, ensuring stable processing ability while preventing oxidation

Inventive Principle:

Principle #23Feedback

3Productivity

If oxygen-containing gas is supplied to increase dissolved oxygen, then processing ability is restored, but substrate oxidation risk increases

Engineering Contradiction:

Improveprocessing abilityVSAvoidsubstrate oxidation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

Alcohol serves as an intermediary that allows high dissolved oxygen concentrations without causing substrate oxidation. It intercepts the harmful interaction between oxygen and substrate, enabling oxygen to be present in high amounts while maintaining both processing ability and substrate protection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical environment by adding alcohol, which modifies oxygen's reactivity toward the substrate. This allows the system to increase dissolved oxygen for processing ability restoration while the alcohol prevents oxidation through chemical interaction

Inventive Principle:

Principle #35Parameter changes

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 ensures a stable and uniform processing ability of TMAH-containing chemical liquids, preventing decreases in etching rates and maintaining consistent substrate processing performance by adjusting dissolved oxygen levels accordingly.

Implementation Method 1

supplying an oxygen-containing gas that contains oxygen gas to a TMAH-containing chemical liquid to make the oxygen-containing gas dissolve in the TMAH-containing chemical liquid

Methodology Applied

Scientific EffectGas dissolution: Absorption (physical)

Implementation Method 2

supplies nitrogen gas into a chemical liquid tank storing the chemical liquid to be supplied to the substrate

Methodology Applied

Scientific EffectGas dissolution: Absorption (physical)

Data Source

PatentUS10186435B2Chemical liquid preparation method of preparing a chemical liquid for substrate processing, chemical liquid preparation unit preparing a chemical liquid for substrate processing, and substrate processing system

Publication Date: 2019.01.22 SCREEN HOLDINGS CO LTD

AI summary

A substrate processing system includes a chemical liquid preparation unit preparing a chemical liquid to be supplied to a substrate and a processing unit which supplies the chemical liquid, prepared by the chemical liquid preparation unit, to the substrate. The chemical liquid preparation unit supplies an oxygen-containing gas, containing oxygen gas, to a TMAH-containing chemical liquid, containing TMAH (tetramethylammonium hydroxide), to make the oxygen-containing gas dissolve in the TMAH-containing chemical liquid.