Substrate Etching Control Using Average Flow Rates

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Solution Overview

Problem

Existing substrate processing methods face challenges in accurately controlling the etching rate and selectivity of titanium nitride (TiN) films relative to tungsten (W) films, leading to inconsistencies in etching processes.

Innovation Solution

A substrate processing apparatus that mixes sulfuric acid with hydrogen peroxide water to create an etchant, which is then controlled using average flow rates of the components to ensure precise etching rates and selectivity, thereby improving the consistency of the etching process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional etching control methods are used, then the etching process can be completed, but the etching rate and selectivity show inconsistencies and errors

Engineering Contradiction:

Improveetching rate precisionVSAvoidetching process consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements feedback control by measuring the actual flow rates of sulfuric acid and hydrogen peroxide water during etching, comparing them with target values, and adjusting the flow rates to minimize deviations. This closed-loop control system continuously monitors and corrects flow rate variations, ensuring consistent etching rates and selectivity across different processing conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from simple flow rate setting to average flow rate control based on actual measurements. By calculating and controlling the average flow rates of etchant components over the etching period, the system compensates for transient variations and maintains precise etching conditions throughout the process.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If simple flow rate control is used, then the system is simple to operate, but the etching amount errors increase

Engineering Contradiction:

Improveflow rate control simplicityVSAvoidetching amount precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces simple mechanical flow rate control with an automated control system that uses sensors, controllers, and algorithms. The system automatically measures actual flow rates, calculates deviations from target values, and adjusts flows accordingly, eliminating the need for manual intervention while improving precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If instantaneous flow rate control is used, then the response is fast, but the overall etching consistency deteriorates due to transient variations

Engineering Contradiction:

Improveflow rate response speedVSAvoidetching rate consistency

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent implements dynamic control by continuously adjusting flow rates based on real-time measurements while maintaining stability through average flow rate control. The system adapts to changing conditions during etching by monitoring and correcting deviations, achieving both fast response and overall consistency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent ensures continuous monitoring and control of etchant flow rates throughout the entire etching process. By maintaining uninterrupted feedback and adjustment, the system prevents transient variations from affecting overall etching consistency while responding quickly to any deviations.

Inventive Principle:

Principle #20Continuity of useful action

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

The use of average flow rate control in the substrate processing apparatus significantly reduces errors in etching amounts, enhances the precision of etching rates, and improves the selectivity of TiN films over W films, leading to more consistent and reliable etching processes.

Implementation Method 1

a mixer configured to mix sulfuric acid as a first component and a second component different from the first component to prepare an etchant

Methodology Applied

Scientific EffectMixing:

Implementation Method 2

a nozzle connected to the mixer and configured to eject the etchant to a substrate

Methodology Applied

Scientific EffectFluid ejection:

Implementation Method 3

a first instantaneous flowmeter provided in the first flow path, and a first flow rate controller provided in the first flow path

Methodology Applied

Scientific EffectFlow measurement:

Data Source

PatentUS12264396B2Substrate processing method

Publication Date: 2025.04.01 TOKYO ELECTRON LTD

AI summary

A substrate processing apparatus includes: a mixer configured to mix sulfuric acid as a first component and a second component different from the first component to prepare an etchant; a nozzle configured to eject the etchant to a substrate; a first component supplier including a first flow path that supplies the first component to the mixer, a first instantaneous flowmeter and a first flow rate controller provided in the first flow path; a second component supplier including a second flow path different from the first flow path and configured to supply the second component to the mixer, a second instantaneous flowmeter and a second flow rate controller provided in the second flow path; and a controller configured to control the first and second flow rate controllers using average flow rates of the first component and the second component during the ejection of the etchant to the substrate.