Drying Gas Flow Direction for Substrate Processing

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Solution Overview

Problem

Conventional substrate processing methods face challenges in uniformly and promptly drying semiconductor wafers or LCD glass substrates, leading to potential watermarks from cleaning liquid droplets and inefficient use of drying gas, as well as risk of water condensation on the drying chamber walls due to direct high-temperature gas exposure.

Innovation Solution

A substrate processing apparatus and method that involves supplying a drying gas, such as IPA steam, into the drying chamber in a horizontal or obliquely downward direction before moving the substrate, allowing the gas to form a liquid film on the cleaning liquid, and then switching to an upward direction after the substrate is fully transferred, ensuring uniform drying and preventing gas-induced condensation on the chamber walls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the substrate is drawn up from the cleaning liquid and then moved to the drying chamber before supplying drying gas, then the drying chamber can be properly prepared, but the substrate surface may not be uniformly dried and watermarks may form

Engineering Contradiction:

Improveuniformity of dryingVSAvoidtime delay between extraction and drying gas supply

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The drying gas is supplied into the drying chamber in advance before the substrate is transferred, so that when the substrate enters the drying chamber, the drying gas is already present and ready to act on the substrate surface immediately, eliminating the time delay and preventing watermark formation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The drying gas supply is made continuous across the transfer process, maintaining a constant drying atmosphere in the drying chamber throughout the substrate movement, ensuring uninterrupted drying action from the moment the substrate enters

Inventive Principle:

Principle #20Continuity of useful action

2Loss of time

If drying gas is supplied in upward direction to fill the drying chamber before substrate transfer, then the drying chamber is prepared in advance, but water condensation may occur on the upper wall of the drying chamber

Engineering Contradiction:

Improvepreparation time of drying chamberVSAvoidwater condensation on chamber wall

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

Instead of supplying drying gas in the conventional upward direction that causes hot gas to contact and condense on the upper wall, the drying gas is supplied in downward or horizontal directions, reversing the flow pattern to avoid condensation on the chamber walls while still achieving proper chamber preparation

Inventive Principle:

Principle #13The other way round (Inversion)

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 reduces the time between substrate extraction and drying gas application, prevents watermark formation, and optimizes gas usage by allowing diffusion to cover the entire substrate surface, while maintaining a uniform drying atmosphere and minimizing gas discharge.

Implementation Method 1

a drying gas formed of a steam of organic solvent having volatility, such as IPA (isopropyl alcohol), is brought into contact with a surface of the cleaned wafer, such that the steam of the drying gas can condense on or adsorb on the surface of the wafer

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 2

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

an inert gas such as N2 gas is supplied to the surface of the wafer so as to remove the moisture on the surface of the wafer whereby the surface of the wafer is dried

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS9070549B2Substrate processing apparatus and substrate processing method

Publication Date: 2015.06.30 TOKYO ELECTRON LTD

AI summary

A drying gas is supplied into a drying chamber in a substantially horizontal direction, an obliquely downward direction descendent from the substantially horizontal direction, or a vertically downward direction under a state where a wafer is immersed in a cleaning liquid in a cleaning tank. The wafer is moved from the cleaning tank into the drying chamber, with the drying gas being supplied into the drying chamber. At this time, the supply of the drying gas into the drying chamber is stopped, under a condition where a part of the wafer is immersed in the cleaning liquid stored in the cleaning tank. After the movement of the wafer into the drying chamber has been finished, a drying gas is supplied into the drying chamber in an obliquely upward direction ascendant from the substantially horizontal direction or a vertically upward direction.