Photolithography Mask Ionization for Electrostatic Charge Control
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Solution Overview
Problem
The semiconductor industry faces challenges with electrostatic charge accumulation on masks during photolithography processes, leading to electrostatic discharge, which damages mask patterns and reduces yield rates, especially with increasing device complexity and higher energy actinic radiation use.
Innovation Solution
Incorporating an ionizer in both the inspection and processing chambers to generate ions that neutralize electrostatic charges on the mask surfaces, reducing the risk of electrostatic discharge and improving fabrication efficiency by shortening the time required for charge neutralization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher energy actinic radiation is used for photolithography, then exposure efficiency is improved, but electrostatic charge accumulation on masks increases leading to discharge and mask damage
Solution Approach 1:
The ionizer is activated before and during the photolithography exposure process to preemptively neutralize electrostatic charges on the mask surface. This preliminary anti-action prevents charge accumulation from reaching discharge levels, allowing the use of higher energy actinic radiation without risking mask damage or pattern distortion.
Solution Approach 2:
The ionizer acts as an intermediary device between the actinic radiation source and the mask. It introduces ions into the chamber that interact with electrostatic charges on the mask, neutralizing them before they can accumulate to harmful levels. This mediator enables the system to operate at higher radiation intensities while maintaining mask integrity.
2Reliability
If traditional electrostatic discharge prevention methods are used, then mask protection is improved, but fabrication time increases due to longer charge neutralization periods
Solution Approach 1:
The ionizer operates continuously throughout the photolithography process rather than requiring separate neutralization steps. This continuous action maintains constant protection against electrostatic charge accumulation, ensuring mask reliability while eliminating idle time for charge neutralization between exposure cycles.
Solution Approach 2:
The ionizer is activated in advance before exposure begins and remains active during the entire process. This preliminary and continuous action ensures that electrostatic charges are neutralized before they can accumulate to problematic levels, preventing mask damage without requiring post-exposure neutralization time.
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 ionizer effectively alleviates electrostatic charge accumulation and discharge, enhancing the yield rate of semiconductor devices and improving the efficiency of the fabrication process by maintaining mask integrity and reducing defects.
Implementation Method 1
generating a plurality of ions by an ionizer
Implementation Method 2
applying a plurality of ions on a mask to neutralize electrostatic charges accumulated on a surface of the mask
Data Source
AI summary
The present disclosure provides a method for fabricating a semiconductor structure, including disposing a mask at a first position in a first chamber, generating; a first plurality of ions toward the mask by an ionizer, forming a photoresist layer on a substrate, receiving the substrate in the first chamber, and exposing the photoresist layer with actinic radiation through the mask in the first chamber.