Photomask Reflectance Control via Pulse Laser Irradiation
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Solution Overview
Problem
Current photomask technologies face challenges in achieving finer patterns for semiconductor devices due to limitations in controlling reflectance for extreme ultraviolet (EUV) lithography, particularly in reducing the critical dimension of patterns formed on substrates.
Innovation Solution
A method of manufacturing photomasks involving a multi-layered structure with alternating layers of different refractive indices, where a blank layer is patterned to form openings and irradiated with pulses of laser light longer than 0.001 seconds, modifying the reflectance and creating a low-reflection part with reduced average reflectance compared to the high-reflection part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a multi-layered structure is formed on the substrate to control reflectance, then the critical dimension of patterns can be reduced, but the manufacturing complexity increases
Solution Approach 1:
The reflective layer is segmented into multiple thin layers with alternating high and low refractive indices, creating a multi-layered structure that provides precise control over reflectance while managing complexity through systematic layering
Solution Approach 2:
Different regions of the photomask have different reflectance characteristics - the first region has high reflectance while the second region has low reflectance, allowing localized optimization for different functional requirements without affecting the entire structure
2Manufacturing precision
If pulse laser irradiation is applied to modify reflectance, then pattern uniformity and reproducibility are improved, but the process time increases
Solution Approach 1:
Pulse laser irradiation is applied periodically to the multi-layered structure, with each pulse lasting substantially greater than 0.001 seconds, enabling controlled modification of reflectance properties while managing total processing time through pulsed rather than continuous irradiation
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
This approach allows for the formation of finer patterns with improved uniformity and reproducibility, enabling the creation of semiconductor devices with smaller critical dimensions and increased process margin, while maintaining high reliability.
Implementation Method 1
at least a portion of the multi-layered structure, exposed by the openings, is irradiated with pulses of light generated by a pulse laser
Implementation Method 2
the reflectance of at least a portion of the multi-layered structure over the projection region of the mask substrate is modified by irradiating the multi-layered structure with pulses of laser light
Implementation Method 3
layers of first and second materials, respectively, are formed alternately one atop the other on the substrate so as to constitute a multi-layered structure
Implementation Method 4
the index of refraction of the first material of the multi-layered structure is different from the index of refraction of the second material
Implementation Method 5
light is projected through a photomask and onto a photosensitive layer on a substrate
Implementation Method 6
The fabricating of semiconductor devices entails the forming of fine patterns on a semiconductor substrate using lithographic techniques in which light is projected through a photomask
Data Source
AI summary
A method of manufacturing a photomask includes forming a multi-layer on a substrate and a blank layer on the multi-layer, patterning the blank layer to form openings exposing the multi-layer on a projection region of the substrate, and irradiating at least a portion of the multi-layer exposed by the openings with pulses of light output by a pulse laser whose pulse width is substantially greater than 0.001 seconds. Thus, the photomask has a reflective layer that includes a low-reflectance part corresponding to that part of the multi-layer irradiated by the light output by the pulse laser.