Photomask Composite Coating for Scratch Recovery and Contamination Control
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Solution Overview
Problem
Particles and scratches on the backside of photomasks used in extreme ultraviolet lithography systems weaken the control accuracy of adjustable angles and carrying forces, leading to detachment and contamination issues, which affect the performance of lithography operations.
Innovation Solution
A protection layer comprising an adhesive, thermoplastic, and hydrophobic layer is applied to the photomask, with gaps between layers to prevent particle travel and facilitate scratch recovery through temperature-induced state changes, enhancing electrostatic stability and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection layer is applied to the photomask, then contamination is reduced and scratch recovery is improved, but device complexity increases
Solution Approach 1:
The protection layer is formed as a composite structure with multiple functional layers: an adhesive layer for bonding, a thermoplastic layer for scratch recovery through temperature-induced state changes, and a hydrophobic layer for contamination resistance. This composite approach enables simultaneous achievement of multiple functions (adhesion, self-healing, and anti-contamination) while maintaining photomask reliability
Solution Approach 2:
The protection layer is segmented into distinct functional sub-layers, each performing a specific function. The adhesive layer provides bonding to the photomask substrate, the thermoplastic layer enables scratch recovery, and the hydrophobic layer prevents contamination. This segmentation allows optimization of each layer's properties independently while resolving the complexity issue through modular design
2Ease of repair
If the photomask is held at elevated temperature for scratch recovery, then scratch recovery is improved, but energy consumption increases
Solution Approach 1:
The thermoplastic layer undergoes phase transition between crystalline and non-crystalline states at specific temperatures. During lithography operations when the photomask is naturally heated, the thermoplastic layer transitions to a non-crystalline state that enables scratch recovery. This phase transition mechanism allows scratch repair to occur during normal operation without requiring additional energy input for heating
Solution Approach 2:
The thermoplastic layer performs scratch recovery autonomously by utilizing the temperature already present during lithography operations. The material's inherent phase transition properties enable it to self-repair scratches without external intervention or additional energy consumption, converting the operational heat into a beneficial repair mechanism
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 protection layer improves the electrostatic force and tilt angle accuracy, reduces contamination, and effectively recovers scratches, ensuring reliable photolithography operations.
Implementation Method 1
the thermoplastic layer comprises a polymer having a crystalline-non crystalline conversion temperature in a range of from about 50 to 60 degrees Celsius
Implementation Method 2
The protection layer improves the electrostatic force and tilt angle accuracy
Data Source
AI summary
The present disclosure provides a photomask and a method for fabricating a semiconductor structure with a photomask. The photomask includes a substrate, and a polymer layer over a surface of the substrate, wherein the polymer layer includes a thermoplastic polymer and a hydrophobic layer, wherein the thermoplastic polymer is between the hydrophobic layer and the surface of the photomask.