EUV Photomask Laser Dosage Mapping for Critical Dimension Uniformity
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Solution Overview
Problem
Extreme ultraviolet (EUV) photomasks face challenges in achieving critical dimension uniformity (CDU) due to variations in pattern elements, which affects the quality of semiconductor devices.
Innovation Solution
A correcting apparatus and method for EUV photomasks that includes a support portion, a chemical supply unit, a light source unit, and a control unit. The control unit generates a laser dosage map to adjust the dosage of a laser beam, ensuring that pattern elements with different critical dimensions are etched at different rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional EUV photomask is used without correction, then the manufacturing process is simple, but the critical dimension uniformity (CDU) of pattern elements deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing a laser dosage map that contains correction data for each region of the photomask before the actual photomask fabrication. This map is generated based on predicted CDU variations and is used to guide the laser irradiation process, allowing corrections to be applied in advance rather than requiring complex real-time adjustments during manufacturing
Solution Approach 2:
The patent implements local quality by dividing the photomask into multiple regions and applying different laser dosages to each region based on its specific CDU characteristics. The laser dosage map contains region-specific correction data that tailors the etching process to local requirements, ensuring each area receives the precise amount of laser energy needed to achieve uniform critical dimensions across the entire photomask
2Manufacturing precision
If uniform laser dosage is applied to all pattern elements, then the processing is simple and fast, but the critical dimension uniformity (CDU) deteriorates due to different etching rates
Solution Approach 1:
The patent applies parameter changes by varying the laser dosage parameter across different regions of the photomask based on pre-calculated CDU compensation values. The laser dosage map contains spatially varying dosage parameters that are applied during irradiation, allowing the system to achieve uniform critical dimensions by adjusting the energy input parameter rather than changing the physical process itself
Solution Approach 2:
The patent replaces complex mechanical adjustment systems with a software-based laser dosage map approach. Instead of using mechanical means to physically adjust each pattern element, the system uses computational algorithms to generate a dosage map that guides the laser irradiation process, substituting mechanical complexity with computational efficiency
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
The solution improves critical dimension uniformity (CDU) of EUV photomasks by precisely controlling the etching rates of pattern elements, leading to enhanced quality and consistency of semiconductor devices.
Implementation Method 1
a light source unit configured to generate a laser beam; and a control unit configured to irradiate the laser beam to the chemical supplied to the main area of the EUV photomask
Implementation Method 2
a reflective layer disposed on the substrate configured to reflect EUV light
Data Source
AI summary
A correcting apparatus of an extreme ultraviolet (EUV) photomask includes: a support portion configured to support an EUV photomask having a main area in which a plurality of pattern elements are arranged, a chemical supply unit configured to supply a chemical to the main area, a light source unit configured to generate a laser beam, and a control unit configured to irradiate the laser beam to the chemical supplied to the main area of the EUV photomask and to, based a laser dosage map for correcting critical dimensions (CDs) of the plurality of pattern elements in the main area, adjust a dosage of the laser beam based on the laser dosage map such that among the plurality of pattern elements, pattern elements having different critical dimensions are etched at different etching rates.