Imprint Lithography Constant Temperature Process
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Solution Overview
Problem
Current imprint lithography techniques face challenges in achieving high accuracy and efficiency for large-scale production of micro and nanoscale structures due to limitations in handling large substrate areas, alignment errors, and thermal expansion issues between different materials used in templates and substrates.
Innovation Solution
A method involving a constant temperature imprint process where a template with a structured surface is arranged parallel to a substrate with a radiation-solidifiable layer, heated to a temperature above the glass transition temperature of the material, and then exposed to radiation for solidification, followed by post-baking, allowing for precise transfer of patterns onto substrates of varying sizes without the need for repeated alignment or dispensation of materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional imprint lithography uses heating and cooling steps, then the mouldable layer can be softened and hardened for pattern transfer, but thermal expansion causes movement in the engaging surfaces reducing accuracy
Solution Approach 1:
The patent changes the temperature parameter from variable (heating and cooling cycles) to constant (maintained at 60°C throughout the process). This eliminates thermal expansion effects while maintaining the mouldable layer's workability through continuous temperature control during imprinting, exposure, and development steps.
Solution Approach 2:
The heated stage serves multiple functions simultaneously: it maintains the mouldable layer in a softened state for imprinting, prevents condensation during exposure, and provides consistent thermal environment for development. This multi-functionality eliminates the need for separate heating and cooling steps.
2Area of stationary object
If step and flash imprint lithography is used for large substrate areas, then coverage can be extended, but repeated alignment and material dispensation are required increasing time and cost
Solution Approach 1:
The patent enables continuous operation by maintaining constant temperature throughout the entire process sequence. The mouldable layer remains in a workable state without requiring cooling between steps, allowing continuous imprinting, exposure, and development on large substrate areas without interruption or repeated material dispensation.
Solution Approach 2:
The substrate and mould are pre-heated to the process temperature before imprinting begins. This preliminary heating ensures the mouldable layer maintains optimal viscosity throughout the entire process sequence, eliminating the need for repeated heating cycles and material dispensation for large area substrates.
3Manufacturing precision
If photolithography is used for fine scale replication, then patterns can be transferred, but diffraction limits the achievable resolution for structures below 50 nm
Solution Approach 1:
The patent replaces the optical system (photolithography) with a mechanical contact system (imprint lithography). By physically pressing the patterned mould into the softened mouldable layer, sub-50 nm structures are replicated through direct mechanical contact, completely avoiding diffraction effects that limit optical methods.
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 method enables high-accuracy, large-area imprints with reduced thermal expansion issues, enabling the production of continuous structures on substrates up to 12 inches or larger in a single step, improving efficiency and cost-effectiveness by using spin-coatable UV-crosslinkable polymers and allowing for the use of non-transparent templates like nickel.
Implementation Method 1
heating the template and the substrate to a temperature Tp by means of a heater device
Implementation Method 2
a substrate with a layer of a material which is devised to solidify upon exposure to radiation
Implementation Method 3
exposing said layer to radiation for solidifying the layer
Implementation Method 4
The steps of heating and cooling the combined template and substrate can bring about movement in the engaging surfaces due to heat expansion
Data Source
AI summary
Method for transferring a pattern from a template (10) having a structured surface (11) to a substrate (12) carrying a surface layer (14) of a material devised to 5 solidify upon exposure to radiation, comprising: arranging said template and substrate mutually parallel in an imprint apparatus, with said structured surface facing said surface layer; heating the template and the substrate to a temperature Tp by means of a heater device (20); and while maintaining said temperature Tp, performing the steps of: pressing the template towards the substrate for imprinting said pattern into said layer; exposing said layer to radiation (19) for solidifying the layer, and—postbaking the layer.