EUV Photomask Patch Layer Repair Method
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Solution Overview
Problem
Photomasks in the semiconductor industry face defects such as particle contamination and material loss during cleaning operations, leading to deviations in pattern shape and critical dimension changes, which affect photolithography performance.
Innovation Solution
A method involving the deposition of a first patch layer, typically chromium-containing, and a second patch layer, typically silicon derivative, on the photomask to alleviate material loss and defects, with the second patch layer having a lower etch rate to protect the first patch layer during cleaning, ensuring the photomask's pattern integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cleaning operations are performed on the photomask to remove particle contamination, then the photomask surface is cleaned, but material loss occurs and pattern integrity deteriorates
Solution Approach 1:
A pellicle layer is applied to the photomask surface before use to prevent particle contamination. This preliminary protective action allows the photomask to be cleaned less frequently, reducing material loss from cleaning operations while maintaining pattern integrity.
Solution Approach 2:
The pellicle layer acts as an intermediary between the photomask and particle contamination. It provides a sacrificial surface that can be cleaned without directly contacting the photomask's patterned layers, thereby preventing material loss and pattern degradation.
2Object-affected harmful factors
If frequent cleaning operations are performed to maintain photomask surface quality, then particle contamination is reduced, but critical dimension changes and pattern shape deviation increase
Solution Approach 1:
The pellicle layer is applied in advance to prevent particle adhesion to the photomask patterns. This preliminary protection reduces the need for frequent cleaning, thereby maintaining critical dimension accuracy and pattern shape fidelity.
Solution Approach 2:
The pellicle layer is designed as a consumable, replaceable component that can be cleaned or replaced instead of subjecting the expensive photomask to repeated cleaning cycles that would degrade its precision.
3Productivity
If the photomask is used for extended periods to improve productivity, then manufacturing output increases, but defects accumulate and pattern integrity deteriorates
Solution Approach 1:
The pellicle layer is applied before photomask use to prevent defect accumulation during extended production runs. This allows the photomask to maintain pattern integrity over longer periods, improving productivity without sacrificing reliability.
Solution Approach 2:
The pellicle layer serves as a mediator that protects the photomask patterns from particle contamination during extended use. It can be cleaned or replaced independently, allowing the photomask to remain in service longer while maintaining pattern integrity.
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 method effectively reduces material loss and maintains the photomask's pattern integrity during cleaning operations, preserving the critical dimensions and pattern shape, thus enhancing photolithography performance.
Implementation Method 1
a first patch layer, typically chromium-containing, and a second patch layer, typically silicon derivative, on the photomask
Implementation Method 2
deposition of a first patch layer, typically chromium-containing, and a second patch layer, typically silicon derivative
Data Source
AI summary
The present disclosure provides a method for forming a semiconductor structure, including forming a photoresist layer over a wafer, exposing the photoresist layer with an actinic radiation by using an EUV photomask, wherein the EUV photomask includes a substrate, a reflective multi-layer stack over the substrate, an absorber layer over the reflective multi-layer stack, and a first patch layer proximal to the absorber layer.