LTPS Multilayer Misalignment Measurement via Vernier Markings
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Solution Overview
Problem
Conventional methods for measuring misalignment in Low Temperature Poly Silicon (LTPS) multilayered structures rely solely on inspection and measuring equipment, leading to inaccuracies and high error rates, especially in detecting slight misalignments, which can result in exposure data errors and decreased product yield.
Innovation Solution
An LTPS multilayered structure with a reference pattern structure and an alignment pattern structure, featuring uniformly distributed references and markings, allows for precise calculation of misalignment by aligning markings on each layer, similar to a vernier caliper principle, enabling accurate and quick measurement of misalignment between stack layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection and measuring equipment is used to measure misalignment, then the measurement process is simple, but the measurement precision is insufficient and error rate is high
Solution Approach 1:
The patent introduces an intermediary measurement mark structure consisting of a reference mark on the first stack layer and a measurement mark on the second stack layer. This intermediary structure mediates the misalignment measurement between layers, enabling precise measurement by comparing the relative positions of these marks rather than directly measuring layer misalignment, thus achieving high measurement precision while maintaining reasonable structural complexity
Solution Approach 2:
The patent creates a copy of the reference mark structure on different stack layers. The reference mark on the first layer and the corresponding measurement mark on the second layer form a copied structure that allows indirect measurement of misalignment. This copying approach enables precise misalignment detection by comparing the relative positions of identical or corresponding mark structures across layers
2Measurement precision
If multiple measurement marks are added to each layer, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent segments the measurement system into distinct components: reference marks on the first stack layer and measurement marks on the second stack layer. This segmentation allows independent optimization of each mark structure and simplifies the overall measurement approach by breaking down the complex misalignment measurement into manageable mark position comparisons
Solution Approach 2:
The patent extends the measurement approach from a single-layer reference system to a multi-layer system by adding vertical dimensionality. The reference mark on the first layer and measurement mark on the second layer create a three-dimensional measurement configuration, enabling precise misalignment measurement across stacked layers while maintaining clear structural relationships
Data Source
AI summary
The present application provides an LTPS multilayered structure, which includes: a first stack layer having a reference pattern structure formed thereon and provided with uniformly distributed first references; and a second stack layer disposed on the first stack layer and having an alignment pattern structure formed thereon and provided with uniformly distributed second references each selectively aligning with one of the first references so that misalignment between the first stack layer and the second stack layer is precisely calculated by markings attached to each of the first references. The present further provides a method for measuring misalignment between a plurality of stack layers in the LTPS multilayered structure.