Substrate Liquid Concentration Control for Overflow-Safe Etching

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Solution Overview

Problem

Existing substrate liquid processing apparatuses lack the flexibility to dynamically change the concentration of processing liquids during semiconductor etching processes, limiting processing flexibility and efficiency.

Innovation Solution

A substrate liquid processing apparatus with a control unit that regulates the concentration of processing liquids by controlling the drainage and supply of phosphoric acid solutions and water, allowing for both constant concentration modes and concentration changing modes, using sensors to monitor liquid surface heights and concentrations for precise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the concentration of processing liquid is regulated to be constant, then the processing stability is improved, but the processing flexibility deteriorates

Engineering Contradiction:

Improveprocessing stabilityVSAvoidprocessing flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic concentration control by enabling the processing liquid concentration to switch between constant regulation mode and changing mode based on processing requirements. The control unit dynamically adjusts the concentration regulation strategy, allowing the system to adapt its behavior rather than maintaining a fixed operational mode throughout the entire processing sequence.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the concentration parameter of the processing liquid from a fixed constant value to a dynamically adjustable parameter. By modifying how the concentration parameter is controlled (from always constant to conditionally variable), the system achieves both stability during constant concentration periods and flexibility during concentration changing periods.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If water is supplied to increase processing liquid volume, then the liquid surface height increases, but liquid overflow risk increases

Engineering Contradiction:

Improveprocessing liquid volumeVSAvoidliquid overflow

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent employs feedback control by using liquid surface height sensors to continuously monitor the processing liquid level. The control unit receives feedback signals from the sensors and automatically adjusts the water supply rate or stops supply when the liquid surface reaches a predetermined height, preventing overflow while ensuring adequate liquid volume for processing.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system prepares for potential overflow by establishing a safety threshold for liquid surface height before it becomes problematic. The control unit proactively stops water supply when the liquid level approaches the predetermined height, cushioning against the harmful effect of overflow before it occurs.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Volume of stationary object

If the drain unit drains processing liquid to decrease volume, then the liquid surface height decreases, but processing liquid loss increases

Engineering Contradiction:

Improveprocessing liquid volumeVSAvoidprocessing liquid loss

Core Design Contradiction:

Volume of stationary objectVSLoss of substance

Solution Approach 1:

The control unit uses feedback from liquid surface height sensors to determine when draining is necessary. Draining is performed only when the liquid surface height exceeds the predetermined threshold, and the draining process is automatically stopped when the height returns to the acceptable range, minimizing unnecessary liquid loss while maintaining safe liquid levels.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Instead of continuously draining or completely replacing the processing liquid, the system performs partial draining only to the extent necessary to reduce the liquid surface height to the acceptable range. This partial action approach minimizes processing liquid loss while still achieving the goal of preventing overflow.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11869780B2Substrate liquid processing apparatus

Publication Date: 2024.01.09 TOKYO ELECTRON LTD

AI summary

A substrate liquid processing apparatus includes a processing liquid storage unit configured to store a processing liquid therein; a processing liquid drain unit configured to drain the processing liquid from the processing liquid storage unit; and a control unit. The control unit performs a first control in a constant concentration mode in which a concentration of the processing liquid in the processing liquid storage unit is regulated to a predetermined set concentration and a second control in a concentration changing mode in which the concentration of the processing liquid is changed. In the second control, a set concentration after concentration change is compared with a set concentration before the concentration change, and when the set concentration after the concentration change is lower, the control unit controls the processing liquid drain unit to start draining of the processing liquid.