Pellicle Assembly Impedance Measurement for Defect Detection
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Solution Overview
Problem
Current technologies lack effective methods to sense and measure defects in pellicles and reticles during exposure processes, which can lead to contamination and defects in semiconductor wafers, and there is a need to estimate the lifetime of pellicles and reticles during transfer or storage.
Innovation Solution
A pellicle assembly and reticle assembly are designed with electrodes and frames that allow for the measurement of potential difference and impedance of the pellicle and reticle membranes and surfaces, enabling defect detection and lifetime estimation through electrical impedance tomography during exposure, transfer, or storage processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pellicle is placed on the reticle to protect from contamination, then protection from external contamination material is improved, but the risk of defect production on wafer increases if the pellicle is damaged
Solution Approach 1:
The patent applies preliminary action by measuring the impedance of the pellicle membrane before the exposure process to detect potential defects. The measurement is performed in advance during transfer or storage, allowing defective pellicles to be identified and replaced before they can cause wafer defects, thus resolving the contradiction between protection and reliability.
Solution Approach 2:
The patent implements feedback by establishing a measurement system that continuously monitors the pellicle's impedance state. The measurement results provide feedback about the pellicle's integrity, enabling real-time detection of defects and informed decisions about whether to proceed with exposure or replace the pellicle, thereby maintaining both protection and reliability.
2Difficulty of detecting and measuring
If electrodes are added to measure pellicle impedance, then defect detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by placing electrodes only at specific locations on the pellicle frame rather than throughout the entire structure. The electrodes are positioned at corners or edges where they can effectively measure the impedance of the pellicle membrane, providing sufficient defect detection capability with minimal added complexity.
Solution Approach 2:
The patent implements universality by designing the electrode structure to serve multiple functions: they provide electrical connection to the pellicle, enable impedance measurement for defect detection, and can potentially serve as structural support elements. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.
3Adaptability or versatility
If impedance measurement is performed during transfer or storage, then measurement timing flexibility is improved, but measurement precision may be affected by environmental factors
Solution Approach 1:
The patent applies parameter changes by measuring the impedance at different frequencies or electrical conditions to optimize the measurement precision. By adjusting the measurement parameters (such as frequency, voltage level, or measurement duration), the system can achieve accurate defect detection regardless of when the measurement is performed during transfer or storage, maintaining both flexibility and precision.
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 solution allows for the detection of defects and estimation of pellicle and reticle lifetime, preventing contamination and ensuring efficient semiconductor fabrication by identifying damaged areas before exposure processes, thus reducing the likelihood of defects and interruptions.
Implementation Method 1
measuring a potential difference between a pair of pellicle electrodes, which are chosen from the plurality of pellicle electrodes, and measuring an impedance of the pellicle membrane
Implementation Method 2
measuring a potential difference between a pair of reticle electrodes, which are chosen from the plurality of reticle electrodes, and measuring an impedance of the reticle
Data Source
AI summary
A pellicle assembly may include a pellicle frame configured to provide a first opening, a pellicle on the pellicle frame, and a plurality of pellicle electrodes arranged along an edge of the pellicle and spaced apart from each other. The pellicle may include a pellicle border having a shape of a tetragonal or rectangular frame, and a pellicle membrane placed on and coupled to a top surface of the pellicle border. Each of the pellicle electrodes may include a contact member placed on and in contact with a top surface of the pellicle membrane.