Fabricating High-Density Interconnects on Ultra-Thin Plastic Films
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Solution Overview
Problem
Current photolithography processes for forming high-density patterns in complex integrated circuits require extremely flat surfaces that are sensitive to elevated temperatures, making it challenging to fabricate sophisticated electronic circuitry on ultra-thin plastic films.
Innovation Solution
A method involving laminating a dry photoresist layer onto a substrate, followed by baking and applying a plastic film, where high-density metal interconnects are formed using photolithography, and the plastic film is then separated from the substrate, allowing for the creation of flexible, thin-film electronic circuitry with multi-layer interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to form high-density patterns on ultra-thin plastic films, then manufacturing precision is improved, but the plastic film surface flatness deteriorates
Solution Approach 1:
A sacrificial adhesive layer is introduced as an intermediary between the plastic film and the substrate. This adhesive layer serves as a temporary bonding medium that allows the plastic film to be laminated to the substrate without requiring the plastic film itself to have excellent surface flatness. After photolithography processing, the adhesive layer is removed, leaving the plastic film with its original properties intact.
Solution Approach 2:
The bonding interface is segmented into multiple functional layers: the plastic film layer, the sacrificial adhesive layer, and the substrate layer. This segmentation allows each layer to perform its specific function independently - the plastic film provides the flexible substrate for circuitry, the adhesive layer provides temporary bonding and surface support during processing, and the substrate provides mechanical strength. The adhesive layer can be removed after serving its purpose.
2Manufacturing precision
If photolithography processing is performed on ultra-thin plastic films, then manufacturing precision is improved, but temperature sensitivity deteriorates
Solution Approach 1:
The sacrificial adhesive layer acts as a thermal intermediary, providing a bonding interface that is less sensitive to temperature variations during the photolithography process. This adhesive layer can accommodate thermal expansion and contraction of the ultra-thin plastic film without compromising the precision of the photolithography patterns, thereby protecting the temperature-sensitive plastic film from thermal damage.
3Device complexity
If multi-layer interconnects are formed on thin-film plastic, then device complexity is improved, but manufacturing difficulty deteriorates
Solution Approach 1:
The sacrificial adhesive layer is applied to the substrate before the plastic film is laminated. This preliminary action creates a ready-to-process surface that simplifies subsequent photolithography operations. The adhesive layer is pre-positioned to provide the necessary surface properties for accurate pattern transfer, and it can be easily removed after the multi-layer interconnect structure is complete, leaving the complex circuitry intact.
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
Enables the fabrication of high-density electronic circuitry on transparent, ultra-thin plastic films with thicknesses ranging from 10 to 500 microns, capable of performing signal transmission and appearing substantially transparent, while maintaining process compatibility with standard semiconductor fab environments.
Implementation Method 1
laminating a dry photoresist layer to a substrate
Implementation Method 2
The photoresist-laminated substrate is baked
Implementation Method 3
laminating a plastic film to the baked, photoresist-laminated substrate
Implementation Method 4
Photolithography typically uses light to transfer a geometric pattern from a photomask to a light-sensitive photoresist on substrate
Implementation Method 5
The processed plastic film is then separated from the substrate
Data Source
AI summary
In accordance with the teachings of one embodiment of the present disclosure, a method of forming high-density metal interconnects on flexible, thin-film plastic includes laminating a dry photoresist layer to a substrate. The photoresist-laminated substrate is baked. An assembly is formed by laminating a plastic film to the baked, photoresist-laminated substrate. One or more electrically conductive interconnect layers are processed on a first surface of the laminated plastic film. The processing of the one or more electrically conductive interconnects includes photolithography. The assembly is baked and soaked in a liquid. The processed plastic film is then separated from the substrate.