Photomask Plasma Cleaning With Stable Ignition and Arc Suppression
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Solution Overview
Problem
The semiconductor manufacturing process faces inefficiencies in photomask cleaning, leading to reduced yields due to imperfections caused by particles or defects on photomasks, which increases the time required for cleaning and affects throughput.
Innovation Solution
The use of atmospheric pressure (AP) plasma treatment apparatus and methods, including a plasma reactor with multiple plasma heads, an optical emission spectrometer for plasma monitoring, and a dielectric barrier discharge to efficiently clean photomasks by removing organic contaminants and modifying surfaces, thereby enhancing throughput and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used to remove particles and defects from photomasks, then cleaning effectiveness is improved, but cleaning time increases substantially reducing throughput
Solution Approach 1:
The patent transforms the cleaning process from conventional methods to atmospheric pressure plasma treatment, changing the physical and chemical parameters of the cleaning mechanism. The plasma state allows for effective removal of organic contaminants at atmospheric pressure, dramatically reducing cleaning time while maintaining effectiveness
Solution Approach 2:
The invention replaces mechanical or chemical cleaning mechanisms with plasma-based cleaning. The plasma reacts chemically with organic contaminants to break them down and remove them, providing effective cleaning without the time-consuming processes of conventional methods
2Productivity
If plasma treatment is applied directly to the sample without an ignition plate, then treatment efficiency is improved, but plasma instability and arcing damage the sample
Solution Approach 1:
The ignition plate serves as an intermediary between the plasma source and the sample. It provides a stable surface for plasma ignition and initial stabilization, preventing direct plasma contact with the sample during the unstable ignition phase. This mediator approach allows the plasma to stabilize before treating the actual sample
Solution Approach 2:
The system performs preliminary plasma ignition and stabilization on the ignition plate before moving to the sample. This preliminary action ensures the plasma is stable and controlled before it contacts the sample, preventing arcing and damage while maintaining treatment efficiency
3Productivity
If multiple plasma heads are used to increase treatment area, then processing capacity is improved, but system complexity and cost increase
Solution Approach 1:
The plasma treatment system is divided into multiple plasma heads that can be independently controlled and positioned. Each plasma head is a modular unit that treats a specific portion of the sample, allowing for increased processing capacity while maintaining manageable system complexity through modular design
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 AP plasma treatment significantly increases photomask cleaning efficiency, reduces manufacturing costs, and improves surface preparation for photoresist layers by ensuring stable plasma and preventing arcing, resulting in higher throughput and improved photomask performance.
Implementation Method 1
a plasma reactor configured to produce AP plasma and positioned above the pedestal
Implementation Method 2
an optical emission spectrometer sensor configured to monitor characteristics of the plasma during ignition and surface treatment
Implementation Method 3
the assistant plate is configured to reduce plasma arcing in the sample support area during plasma treatment
Data Source
AI summary
Methods and apparatus leverage dielectric barrier discharge (DBD) plasma to treat samples for surface modification prior to photomask application and for photomask cleaning. In some embodiments, a method of treating a surface with AP plasma includes igniting plasma over an ignition plate where the AP plasma is formed by one or more plasma heads of an AP plasma reactor positioned above the ignition plate, monitoring characteristics of the AP plasma with an optical emission spectrometer (OES) sensor to determine if stable AP plasma is obtained and, if so, moving the AP reactor over a central opening of an assistant plate where the central opening contains a sample under treatment and where the assistant plate reduces AP plasma arcing on the sample during treatment. The AP reactor scans back and forth over the central opening of the assistant plate while maintaining stabilized AP plasma to treat the sample.