Photomask Plasma Cleaning With OES Monitoring and Arc Protection
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Solution Overview
Problem
The existing photomask cleaning processes in semiconductor manufacturing are inefficient, leading to reduced throughput and increased costs due to the need for frequent cleaning and potential damage from particles or defects on photomasks.
Innovation Solution
The use of atmospheric pressure (AP) plasma treatment with a plasma reactor and optical emission spectrometer (OES) monitoring to efficiently clean photomasks, removing organic defects and photoresist layers while preventing arcing damage, using argon gas and water vapor to control plasma stability and residence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional photomask cleaning processes are used, then photomasks can be cleaned, but the cleaning throughput is low and the process takes substantial time
Solution Approach 1:
The patent changes the physical and chemical parameters of the cleaning process by using atmospheric pressure plasma instead of traditional vacuum plasma or chemical cleaning methods. The plasma is generated using specific gas compositions (oxygen, argon, nitrogen in controlled ratios) and RF power parameters to achieve effective cleaning with shorter processing time and higher throughput
Solution Approach 2:
The patent replaces traditional mechanical or chemical cleaning systems with a plasma-based cleaning system. The plasma chemistry provides gentle yet effective removal of photoresist and organic contaminants without the mechanical contact or harsh chemicals, reducing cleaning time while maintaining photomask integrity
2Reliability
If photomasks are cleaned frequently to maintain performance, then photomask performance is maintained, but manufacturing throughput is reduced
Solution Approach 1:
The plasma cleaning system provides more effective and consistent cleaning performance, removing organic defects and photoresist layers completely. This superior cleaning efficacy extends photomask life and maintains performance over more uses, reducing the frequency of replacement and maintaining high manufacturing throughput
Solution Approach 2:
By controlling plasma parameters (gas composition, power, pressure, exposure time), the process achieves optimal cleaning that maintains photomask integrity. This allows frequent cleaning cycles without damaging the photomask, maintaining both reliability and productivity
3Object-generated harmful factors
If plasma treatment is applied to clean photomasks, then organic defects are removed, but plasma arcing may damage the photomask
Solution Approach 1:
The patent carefully controls plasma generation parameters including RF power levels, gas pressure, and gas composition to prevent arcing. By maintaining atmospheric pressure and using specific gas ratios, the plasma remains stable and non-arcing while still effectively removing organic contaminants
Solution Approach 2:
The patent uses gas flow and plasma chamber design as intermediaries to distribute plasma uniformly across the photomask surface. This prevents localized overheating and arcing while maintaining effective cleaning. The gas acts as a buffer that mediates between the plasma energy and the photomask surface
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 method significantly increases photomask cleaning throughput, reduces manufacturing costs, and enhances surface modification capabilities, ensuring stable plasma treatment and minimizing damage to photomasks.
Implementation Method 1
a plasma reactor configured to produce AP plasma
Implementation Method 2
an optical emission spectrometer sensor configured to monitor characteristics of the plasma during ignition and surface treatment
Implementation Method 3
wherein the assistant plate is configured to reduce plasma arcing in the sample support area during plasma treatment
Implementation Method 4
a plurality of gas nozzles configured to flow one or more gases around the one or more plasma heads, wherein the plurality of gas nozzles is configured to flow a mixture of argon gas and oxygen-based gas
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.