Photomask Heat Radiation Layer Thermal Deformation
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Solution Overview
Problem
Thermal deformation of transparent substrates in photomasks during lithography processes leads to overlay errors due to heat absorption and expansion, affecting pattern accuracy and precision.
Innovation Solution
Incorporating a heat radiation layer on the sidewalls and bottom surface of the photomask substrate, along with light blocking or phase shift layers, to manage heat dissipation and stabilize the substrate during exposure, and optionally using high strength support layers with lower thermal expansion coefficients to minimize substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If light blocking patterns are disposed on the photomask to block light during lithography, then light blocking function is improved, but heat absorption increases causing thermal deformation
Solution Approach 1:
The patent applies this principle by converting the harmful heat generated by light blocking patterns into a manageable thermal field through the heat radiation layer. The heat radiation layer absorbs the thermal energy that would otherwise cause substrate deformation and redirects it through controlled thermal conduction to the substrate's backside, where it can be dissipated. This transforms the harmful thermal effect into a controlled thermal management process.
Solution Approach 2:
The heat radiation layer serves as an intermediary between the light blocking patterns and the substrate. It mediates the thermal energy transfer by providing a dedicated thermal conduction path that separates the light blocking function from the substrate structure, allowing heat to be managed independently from the optical function.
2Illumination intensity
If transparent substrate is used to allow light transmission, then light transmission function is improved, but thermal expansion occurs due to heat conduction from light blocking patterns
Solution Approach 1:
The patent segments the substrate into functional zones by adding the heat radiation layer, which creates a dedicated thermal management pathway. This segmentation allows the substrate to maintain its light transmission properties while the heat radiation layer handles thermal expansion control independently.
Solution Approach 2:
The patent changes the thermal parameters of the substrate system by introducing the heat radiation layer with specific thermal conductivity properties. This layer modifies the overall thermal behavior of the substrate, enabling it to conduct heat away from critical areas while maintaining optical transparency.
3Temperature
If heat radiation layer is added to dissipate heat, then thermal management is improved, but device complexity increases
Solution Approach 1:
The heat radiation layer is designed to perform multiple functions simultaneously: it provides thermal conduction pathways, acts as a structural support layer, and serves as an interface for heat dissipation. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
4Manufacturing precision
If light blocking layer is disposed on top surface to block light, then light blocking precision is improved, but overlay error occurs due to substrate deformation
Solution Approach 1:
The heat radiation layer provides beforehand cushioning by pre-establishing thermal conduction pathways that prevent excessive heat accumulation before it can cause significant substrate deformation. This proactive thermal management cushioning protects the overlay accuracy from degradation during lithography exposure.
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 heat radiation layer effectively dissipates accumulated heat, reducing substrate expansion and deformation, while the high strength support layers maintain pattern accuracy by suppressing lateral expansion, thereby minimizing overlay errors and enhancing photomask performance.
Implementation Method 1
the light blocking patterns may absorb a large amount of optical energy of the light irradiating the photomask, thereby generating heat. The heat may be conducted to the transparent substrate of the photomask
Implementation Method 2
a heat radiation layer disposed on sidewalls and a bottom surface of the light transmission substrate
Implementation Method 3
the light blocking patterns may absorb a large amount of optical energy of the light irradiating the photomask, thereby generating heat
Implementation Method 4
The heat may be conducted to the transparent substrate of the photomask, and the transparent substrate may be expanded and deformed due to the heat
Data Source
AI summary
Photomask blanks are provided. One of the photomask blanks includes a light transmission substrate, a light blocking layer disposed on a top surface of the light transmission substrate, and a heat radiation layer disposed on sidewalls and a bottom surface of the light transmission substrate. Related photomasks and fabrication methods of the photomasks are also provided.