Substrate Liquid Processing Apparatus Concentration Control

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Solution Overview

Problem

The concentration of chemical liquid components in a processing bath used for substrate processing, such as sulfuric acid and hydrogen peroxide, decreases below a predetermined limit when multiple substrates are immersed, leading to longer processing times and potential resist removal failures.

Innovation Solution

A substrate liquid processing apparatus with a controller that performs feedback control to replenish chemical liquid components, including sulfuric acid and hydrogen peroxide, to maintain concentrations above a lower limit, and an additional pre-replenishment step before substrate introduction to offset concentration reductions caused by substrate immersion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple substrates are immersed in the processing liquid for batch processing, then processing efficiency is improved, but the concentration of chemical liquid components falls below the allowable lower limit

Engineering Contradiction:

Improvebatch processing efficiencyVSAvoidconcentration of chemical liquid components

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The system performs preliminary action by detecting the introduction of substrates and proactively replenishing chemical liquid components before the concentration falls below the allowable lower limit. The controller monitors substrate introduction and triggers replenishment in advance, preventing the concentration from dropping to problematic levels during batch processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control by using a concentration detecting unit to continuously monitor the chemical liquid component concentration in the processing bath. When the concentration approaches or falls below the allowable lower limit, the feedback signal triggers the chemical liquid component supply unit to replenish the processing liquid, thereby maintaining concentration within the required range throughout batch processing.

Inventive Principle:

Principle #23Feedback

2Quantity of substance

If the concentration of chemical liquid components falls below the allowable lower limit, then the processing time increases, but maintaining high concentration requires continuous replenishment

Engineering Contradiction:

Improveconcentration of chemical liquid componentsVSAvoidprocessing time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The feedback control system continuously monitors concentration and triggers replenishment only when necessary (when concentration approaches or falls below the lower limit). This on-demand replenishment strategy maintains optimal concentration levels without requiring continuous addition of chemical components, thereby minimizing unnecessary processing time while ensuring concentration remains effective throughout the batch processing cycle.

Inventive Principle:

Principle #23Feedback

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 minimizes the period where chemical liquid concentrations fall below the allowable limit, ensuring efficient resist removal processing and maintaining throughput by maintaining optimal chemical concentrations, thus preventing processing failures.

Implementation Method 1

a concentration detecting unit configured to detect a concentration of the chemical liquid components contained in the processing liquid

Methodology Applied

Scientific EffectConcentration detection:

Implementation Method 2

a controller configured to perform a first control as a feedback control that causes the chemical liquid component supply unit to replenish the processing liquid with the chemical liquid components such that the concentration of the chemical liquid components contained in the processing liquid within the processing bath does not become less than a predetermined allowable lower limit

Methodology Applied

Scientific EffectFeedback control: Feedback

Implementation Method 3

the controller performs, in addition to the first control, a second control that causes the chemical liquid component supply unit to replenish the processing liquid with the chemical liquid components in a predetermined amount required to offset a reduction in concentration of the chemical liquid components caused by the introduction of the substrate

Methodology Applied

Scientific EffectConcentration offset:

Data Source

PatentUS10928732B2Substrate liquid processing apparatus, substrate liquid processing method, and storage medium

Publication Date: 2021.02.23 TOKYO ELECTRON LTD

AI summary

Disclosed is a substrate liquid processing apparatus including: a processing bath in which a processing liquid is stored; a chemical liquid component supply unit that supplies chemical liquid components; a concentration detecting unit that detects a concentration of the chemical liquid components; and a controller configured to perform a first control as a feedback control that replenishes the processing liquid with the chemical liquid components such that the concentration of the chemical liquid components contained in the processing liquid within the processing bath does not become less than a predetermined allowable lower limit, based on the concentration of the chemical liquid components detected by the concentration detecting unit. In addition, the controller performs a second control that replenishes the processing liquid with the chemical liquid components in a predetermined amount required to offset a reduction in concentration of the chemical liquid components caused by the introduction of the substrate.