Mask Inspection Using Amplitude Converted Value for Linearity
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Solution Overview
Problem
Existing mask inspection methods are insufficient in reliability due to the variability in distortion reduction by tension application, particularly for masks with higher-order component distortions, leading to inaccurate predictions of mask linearity and increased defective product rates.
Innovation Solution
A method involving the calculation of a simple amplitude converted value ΔC, where tension is adjusted to ensure ΔC is within a threshold, allowing for reliable evaluation of mask linearity by minimizing the impact of lower-order distortions and predicting higher-order component distortions, thereby improving inspection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tension is applied to the mask to reduce distortion, then mask linearity is improved, but the reliability of inspection is worsened due to variability in distortion reduction
Solution Approach 1:
The patent introduces a new parameter 'simple amplitude converted value ΔC' that transforms the complex distortion characteristics into a measurable quantity. By changing the parameter space from direct geometric distortion to amplitude conversion, the inspection becomes more reliable and reproducible across different masks and inspection conditions.
Solution Approach 2:
The patent replaces direct mechanical measurement of mask distortion with an optical measurement system that captures reference point coordinates. The distortion evaluation is substituted from physical geometric measurement to optical coordinate analysis, improving inspection reliability through non-contact measurement and standardized data processing.
2Ease of operation
If standard inspection methods are used, then inspection process is simple, but inspection accuracy is worsened due to inability to predict higher-order component distortions
Solution Approach 1:
The patent segments the distortion evaluation into two independent parts: lower-order distortion (handled by tension application) and higher-order distortion (evaluated through reference point coordinate analysis). This segmentation allows simple inspection processes to achieve high accuracy by systematically addressing different distortion components separately.
Solution Approach 2:
The patent introduces reference points as intermediaries between the mask structure and the measurement system. These reference points serve as mediators that translate complex mask distortion into measurable coordinate data, enabling accurate linearity evaluation without complicating the inspection process.
3Manufacturing precision
If tension is applied to reduce mask distortion, then mask quality is improved, but defective product rate increases due to individual variability in distortion reduction
Solution Approach 1:
The patent implements a feedback mechanism where the simple amplitude converted value ΔC is calculated from reference point coordinates and used to evaluate mask linearity. This feedback allows for objective assessment of mask quality and identification of defective products based on quantifiable criteria, reducing defective product rates through standardized evaluation.
Solution Approach 2:
The patent performs preliminary measurement of reference point coordinates before final mask assembly. By evaluating distortion characteristics in advance using the amplitude conversion method, defective masks can be identified and rejected before they cause production issues, improving overall product quality without reducing productivity.
Data Source
AI summary
A method for inspecting a mask may include a first calculation step of calculating the y components y0 to yn of the coordinates of reference points in a y direction, an adjustment step of adjusting a tension so that a simple amplitude converted value ΔC calculated based on the y components y0 to yn becomes less than or equal to a first threshold, the tension being applied to the mask, and a second evaluation step of evaluating linearity of the mask with reference to amplitude ΔS calculated based on the y components of the coordinates of the reference points of the mask under the tension adjusted in the adjustment step.