Substrate Cleaning Nozzle Control for Resist Residue
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Solution Overview
Problem
Defective development in substrate cleaning processes due to incomplete removal of resist dissolved substances, often caused by the formation of an intermediate semi-dry area during the cleaning process, where centrifugal force causes liquid scattering and residue on the substrate.
Innovation Solution
A substrate cleaning method that involves ejecting a cleaning liquid and dry gas to form specific areas on the substrate, with real-time monitoring and adjustment of process parameters such as gas flow rate, nozzle movement speed, and substrate rotation speed to maintain an intermediate area width within a predetermined threshold, preventing liquid scattering and residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cleaning liquid is supplied to a rotating substrate to spread all over the surface, then the cleaning liquid can remove resist dissolved substances, but an intermediate semi-dry area forms where liquid scattering occurs causing defective development
Solution Approach 1:
A dry gas is supplied to the central portion of the substrate before the cleaning liquid reaches that area. This preliminary drying action prevents the formation of the harmful intermediate semi-dry area where liquid scattering occurs, while still allowing the cleaning liquid to effectively remove resist substances from the peripheral areas.
Solution Approach 2:
The harmful intermediate semi-dry area is eliminated by extracting the cleaning liquid through evaporation by dry gas before it can reach the central portion of the substrate. This prevents the liquid scattering phenomenon that causes defective development while maintaining cleaning effectiveness in other areas.
2Productivity
If the cleaning-liquid supply position is moved from central side toward peripheral side, then the dry area spreads outward by centrifugal force, but the intermediate area may still cause liquid scattering and residue
Solution Approach 1:
Dry gas is supplied in advance to the central portion of the substrate to create a dry area before the cleaning liquid reaches that region. This preliminary action prevents the formation of the intermediate semi-dry area that causes liquid scattering, ensuring reliable development quality while maintaining efficient cleaning through the moving supply position.
3Productivity
If the substrate rotation speed is increased to improve cleaning, then the centrifugal force increases causing more liquid scattering in the intermediate area
Solution Approach 1:
Dry gas is supplied to the central portion of the substrate before the cleaning liquid arrives, creating a dry area that prevents the formation of the intermediate semi-dry zone. This allows the substrate to rotate at speeds sufficient for effective cleaning without the harmful liquid scattering that would occur in the intermediate area.
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
Significantly reduces the occurrence of defective development by ensuring complete removal of resist substances, enhancing the robustness of the cleaning process and maintaining quality even under varying conditions.
Implementation Method 1
the dry area formed on the central portion of the substrate spreads outward by an action of the centrifugal force
Implementation Method 2
a dry gas is ejected from a gas nozzle positioned above the substrate, to the central portion of the surface of the substrate
Data Source
AI summary
A substrate cleaning method includes: a first step in which a cleaning liquid is ejected from a nozzle N2 to a central portion of a wafer W; a second step in which a dry gas is ejected from a nozzle N3 to the central portion of the wafer W to form a dry area; a third step in which the cleaning liquid is ejected from the nozzle N2 while the nozzle N2 is moved from a central side of the wafer W to a peripheral side thereof; a fourth step in which a width of an intermediate area generated between a wet area and the dry area is acquired; and a fifth step in which, when the width of the intermediate area exceeds a predetermined threshold value, a process parameter is changed such that the width of the intermediate area becomes the threshold value or less.