Pellicle Frame Pre-Deflection for Photomask Stability
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Solution Overview
Problem
The deformation and deflection of photomasks during exposure operations due to the coupling with pellicle frames, which affects the accuracy of pattern transfer in semiconductor and display panel manufacturing, are not adequately addressed by existing solutions, as they either increase costs or compromise the rigidity and handling of the pellicle frames.
Innovation Solution
A pellicle frame with pre-deflected side bars, where at least one pair of side bars is deflected by an amount corresponding to 0.01-1% of their length, matching the direction and magnitude of the photomask's self-weight deflection, to minimize the change in photomask deformation when coupled, thereby reducing the impact of pellicle-induced distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rigidity of the pellicle frame is reduced to allow it to imitate the shape of the photomask, then the deformation of the photomask is reduced, but the handling and manufacturing difficulty increases
Solution Approach 1:
The pellicle frame is pre-deflected in the opposite direction to the expected photomask deflection before assembly. This preliminary action allows the frame to compensate for photomask deformation during exposure, reducing pattern distortion while maintaining standard frame rigidity for easy manufacturing and handling.
Solution Approach 2:
The invention changes the deflection parameter of the pellicle frame by introducing a predetermined reverse deflection. This parameter modification allows the frame to dynamically compensate for photomask deformation under exposure conditions while maintaining adequate rigidity for manufacturing and handling.
2Manufacturing precision
If the thickness of the photomask is increased to reduce self-weight deflection, then the pattern accuracy is improved, but the cost and weight increase
Solution Approach 1:
The pellicle frame acts as an intermediary element that compensates for photomask deflection. By pre-deflecting the frame in the opposite direction, it counteracts the effect of photomask self-weight deflection, allowing thin, lightweight photomasks to maintain pattern accuracy during exposure.
3Ease of manufacture
If the pellicle frame is made perfectly flat, then the manufacturing is simplified, but the photomask deformation under self-weight cannot be compensated
Solution Approach 1:
Instead of making the frame perfectly flat, a predetermined reverse deflection is introduced during manufacturing. This preliminary action prepares the frame to compensate for photomask deformation under exposure conditions, balancing manufacturing simplicity with shape stability compensation.
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 approach effectively suppresses the change in photomask deflection, ensuring pattern accuracy by aligning the pellicle frame's deflection with the photomask's self-weight deflection, thus preventing interference with the optical system's intended exposure and reducing manufacturing complexity.
Implementation Method 1
at least one pair of side bars is/are deflected by an amount corresponding to 0.01-1% of their length
Data Source
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AI summary
A pellicle frame and a pellicle made with it is proposed in which at least one pair of the side bars of the frame are made to have a deflection (bow) which has an amount or a distance of displacement measured at the middle point of the side bar accounting for 0.01 through 1 % of the length of the respective side bar.