FEP Imprint Lithography Stamp for High-Aspect-Ratio Via Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wafer level packaging techniques face challenges in forming reconstituted substrates and redistribution layers due to defects like die shift and the cost, equipment intensity, and time consumption of conventional photolithography processes, which are sensitive to topographic effects and limited by achievable depth of focus.
Innovation Solution
The use of an imprint lithography stamp with a fluorinated ethylene propylene (FEP) copolymer material, featuring a backing plate with through-holes and a patterned stamp body with protrusions, for forming redistribution layers by physically imprinting patterns into polymer layers at controlled temperatures and pressures, allowing for high aspect ratio via formation without feature deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional photolithography processes are used to form redistribution layers, then the process can be performed with standard equipment, but the process is costly, equipment intensive, time consuming, and sensitive to topographic effects with limited depth of focus
Solution Approach 1:
The patent replaces conventional photolithography (optical system) with imprint lithography (mechanical system). The imprint lithography stamp physically imprints the pattern directly onto the polymer layer through contact, eliminating the need for optical exposure systems and associated photomasks. This mechanical approach is less sensitive to topographic effects and achieves the required patterning without the limitations of depth of focus in optical systems
Solution Approach 2:
The patent uses a master stamp that contains the desired pattern, which is then used to create imprints on polymer layers. This copying approach allows the same master stamp to be reused multiple times to pattern multiple redistribution layers, reducing the need for creating new photomasks for each layer and improving manufacturing efficiency
2Manufacturing precision
If conventional photolithography is used for via formation, then the process can handle standard aspect ratios, but the process fails to achieve high aspect ratio vias without feature deformation
Solution Approach 1:
The patent changes the physical parameters of the polymer layer by controlling its temperature and viscosity during the imprinting process. By maintaining the polymer in a softened state during stamp contact and then cooling it to solidify the pattern, the process can form high aspect ratio vias without feature deformation. The controlled temperature parameters enable the polymer to flow into high aspect ratio features and then lock in the pattern upon cooling
3Manufacturing precision
If higher processing temperatures are used to form high aspect ratio vias, then the via formation is successful, but feature deformation occurs with conventional methods
Solution Approach 1:
The patent employs periodic thermal cycling of the polymer layer - heating it to a softened state during imprinting, then cooling it to solidify the pattern. This periodic temperature variation allows the polymer to be pliable during pattern formation and then stable after patterning, preventing feature deformation while enabling high aspect ratio via formation
Solution Approach 2:
The patent applies a release agent or coating to the stamp surface beforehand to prevent adhesion between the polymer and stamp during high temperature processing. This pre-applied protective measure allows the polymer to be heated to the required temperature for high aspect ratio via formation without causing feature deformation through premature solidification or adhesion to the stamp
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 the formation of high aspect ratio vias in dielectric polymer materials at higher processing temperatures, reducing feature deformation and improving the accuracy and efficiency of redistribution layer formation, thereby enhancing wafer level packaging capabilities.
Implementation Method 1
heating the FEP copolymer material to a melting point of the FEP copolymer material
Implementation Method 2
injecting the FEP copolymer material into the cavity and into the plurality of through-holes in an injection molding process
Implementation Method 3
curing the FEP copolymer material to form the stamp body
Data Source
AI summary
An imprint lithography stamp includes a stamp body having a patterned surface and formed from a fluorinated ethylene propylene copolymer. The imprint lithography stamp further includes a backing plate with a plurality of through-holes with portions of the stamp body extending into the through-holes to adhere the stamp body to the backing plate. The patterned surface of the stamp body has a plurality of protrusions extending from the stamp body, which are used to form high aspect ratio features at high processing temperatures. A mold design for forming the imprint lithography stamp and an injection molding process for forming the imprint lithography stamp are also provided.