Photomask Defect Correction Using Gas Field Ion Source
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Solution Overview
Problem
Conventional photomask defect correction methods using gallium ion beams deteriorate the optical characteristics of light transmission portions and restrict additional processing due to Ga ion accumulation, leading to limitations in transmissivity and precision.
Innovation Solution
A photomask defect correction method utilizing a focused ion beam formed by a gas field ion source, which includes a gas field ion source for generating gas ions, allowing for precise defect correction without deteriorating optical characteristics by using rare gas ions like argon, and incorporating an electron beam for charge neutralization to prevent excessive trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focused ion beam using liquid metal gallium ion source is used for defect correction, then the defect can be corrected using etching capability, but the transmissivity of the light transmission portion deteriorates due to Ga ion injection and accumulation
Solution Approach 1:
The patent changes the ion species from gallium ions to rare gas ions (helium, neon, argon, krypton, xenon). This parameter change resolves the contradiction because rare gas ions do not deteriorate light transmissivity while maintaining the etching capability needed for defect correction precision.
Solution Approach 2:
The patent uses rare gas ions as a substitute (copy) for gallium ions, replicating the beneficial etching function while eliminating the harmful optical absorption effect. The rare gas ions serve as an alternative ion source that copies the functional role without the detrimental side effects.
2Reliability
If wet cleaning is performed to remove accumulated Ga ions, then some Ga ions can be removed, but the glass or quartz substrate is scrapped by selective cutting leading to phase difference and optical characteristic deterioration
Solution Approach 1:
The patent extracts and eliminates the harmful gallium ions by completely replacing them with rare gas ions. This prevents the need for wet cleaning operations that cause substrate damage, thereby maintaining surface uniformity and optical characteristics while still achieving effective ion removal.
Solution Approach 2:
The patent converts the harmful effect of ion accumulation into a beneficial situation by using rare gas ions that do not accumulate harmfully. The ions can still be removed when needed without causing substrate damage, turning a previously harmful process into a benign one.
3Manufacturing precision
If additional processing is performed to recorrect uncut portions or loss portions, then the shape is improved, but the Ga ion injection amount increases causing further transmissivity deterioration
Solution Approach 1:
The patent changes the ion species parameter to rare gas ions, which allows multiple additional processing steps to be performed without the transmissivity deterioration that occurs with gallium ions. This enables complete defect correction while maintaining optical quality.
Solution Approach 2:
The patent enables continuous defect correction operations using rare gas ions without interruption or transmissivity loss. Multiple correction passes can be performed continuously, ensuring complete correction while maintaining consistent optical properties throughout the process.
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
Enables rapid and precise defect correction with maintained optical transmissivity, allowing for repeated processing without ion injection removal, and improves processing efficiency and reliability by preventing excessive trimming and maintaining optical quality.
Implementation Method 1
a focused ion beam formed of gas ions and generated by an ion beam irradiation system including a gas field ion source (GFIS)
Implementation Method 2
irradiating a focused ion beam formed of gas ions and generated by an ion beam irradiation system including a gas field ion source (GFIS) to the portion to be corrected and correcting the defect
Implementation Method 3
incorporating an electron beam for charge neutralization to prevent excessive trimming
Data Source
AI summary
A photomask defect correction method and device correct an opaque or a clear defect of a photomask. An opaque or clear defect in a portion of a photomask to be corrected is observed and information of the observed defect for performing correction of the defect is acquired. The observed defect is corrected in accordance with the acquired defect information by irradiating the observed defect with a focused ion beam from an ion beam irradiation system having a gas field ion source that generates gas ions for forming the focused ion beam. The gas ions may be hydrogen ions, nitrogen ions, oxygen ions, fluorine ions or chlorine ions.