Substrate Humidification for Electrostatic Charge Dissipation
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Solution Overview
Problem
Substrates carried into substrate processing chambers often have significant electrostatic charges, which can lead to electrostatic discharge when contacted by chemical or neutralizing liquids, causing damage to the substrate surfaces, and existing neutralizing liquids may not adequately eliminate these charges.
Innovation Solution
A substrate processing method and apparatus that uses a humidified gas with higher humidity than the chamber atmosphere to diffuse electrical charges on the substrate before liquid discharge, followed by a spin-drying step to remove the liquid, thereby preventing electrostatic discharge and substrate damage. This method includes supplying humidified gas before and during the liquid discharging step and ending it before the spin-drying step to maintain a low-humidity atmosphere for effective drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If neutralizing liquid is supplied onto the substrate to eliminate electrostatic charge, then electrostatic discharge is prevented, but the substrate may still suffer damage if the charge amount is too large for the neutralizing liquid to handle
Solution Approach 1:
The substrate surface is humidified with water vapor before liquid supply to pre-remove electrostatic charges. This preliminary action reduces the charge amount before the actual liquid processing, preventing the situation where large charges cause substrate damage despite neutralizing liquid application
Solution Approach 2:
Water vapor serves as an intermediary substance between the charged substrate and the processing liquid. The water vapor molecules transfer to the substrate surface, providing a conductive path that gradually dissipates electrostatic charges before liquid contact, thereby preventing electrostatic discharge damage
2Reliability
If neutralizing liquid is supplied onto the substrate, then electrostatic discharge is suppressed, but this approach is not desirable for certain substrate types or chemical liquid combinations
Solution Approach 1:
Water vapor acts as a universal intermediary that can be applied to any substrate type without compatibility concerns. Unlike neutralizing liquids that may react adversely with certain substrates or chemical liquids, water vapor provides a safe, universally applicable method for electrostatic charge removal
Solution Approach 2:
The method replaces chemical neutralization with physical humidification. Instead of using chemical reactions between neutralizing liquids and charged surfaces, the patent uses physical water vapor deposition and conduction, eliminating chemical compatibility issues while maintaining electrostatic discharge suppression
3Productivity
If the substrate is rotated at high speed for spin-drying, then liquid removal is effective, but electrostatic discharge may occur during the liquid discharging step before drying
Solution Approach 1:
The substrate surface is humidified with water vapor before liquid discharging begins. This pre-treatment ensures that electrostatic charges are removed in advance, allowing the subsequent liquid processing and high-speed spin-drying to proceed without electrostatic discharge damage
Solution Approach 2:
The water vapor supply continues during the liquid discharging step, maintaining continuous electrostatic charge removal throughout the processing. This ensures that even as liquid is applied and the substrate rotates, any generated charges are immediately neutralized, preventing discharge during the entire operation
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 method effectively suppresses electrostatic discharge during liquid processing, preventing damage to the substrate surfaces by ensuring electrical charges are removed before liquid contact, and allows for satisfactory drying of the substrate.
Implementation Method 1
supplying humidified gas with a humidity higher than the humidity within the chamber onto the main surface of the substrate to remove electrical charges carried on the substrate
Implementation Method 2
rotating the substrate about a predetermined rotational axis after the liquid discharging step to spin off the liquid component from the main surface of the substrate
Data Source
AI summary
A substrate processing method includes a liquid discharging step of discharging liquid through a nozzle toward a predetermined supply region on the main surface of a substrate held on a substrate holding unit within a chamber, a humidified gas supplying step of supplying humidified gas with a humidity higher than the humidity within the chamber onto the main surface of the substrate to remove electrical charges carried on the substrate, and a spin-drying step of rotating the substrate about a predetermined rotational axis after the liquid discharging step to spin off the liquid component from the main surface of the substrate. The humidified gas supplying step is started before the start of the liquid discharging step and ended at a predetermined termination timing after the start of the liquid discharging step and before the spin-drying step.