Porous Polymeric Membrane with Tear-Prevention Ring
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Solution Overview
Problem
Standard techniques for semiconductor manufacturing are inadequate for producing large-surface-area microporous membranes with desirable properties, as they often result in curling and contamination issues due to non-uniformity and metallic residues.
Innovation Solution
A tear-resistant liquid-filtering porous polymeric membrane is created using photolithography, featuring a pore region with a minimum dimension of less than 100 microns and a surrounding tear-resistant boundary region, which is achieved by depositing a photoresist layer, exposing it to light, developing, etching, and removing layers to prevent tearing and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional semiconductor manufacturing techniques are used to produce large-surface-area microporous membranes, then high aspect ratio holes can be achieved, but the membranes exhibit curling and contamination from hard mask layer
Solution Approach 1:
The patent removes the hard mask layer entirely from the process, using only a photoresist layer to define the pore pattern. This extraction of the problematic hard mask layer eliminates the source of metallic contamination while maintaining the ability to produce high aspect ratio holes through direct etching of the photoresist pattern into the membrane material.
Solution Approach 2:
The patent uses a disposable photoresist layer that is applied, patterned, and then removed after serving its purpose as a temporary mask during etching. This single-use approach avoids the need for permanent hard mask layers that leave contaminating residues, while the photoresist can be completely removed without leaving metallic contamination.
2Productivity
If thin polymeric membrane material is used to achieve high filtration efficiency, then filtration performance improves, but the membrane becomes prone to tearing
Solution Approach 1:
The patent creates a boundary region with different properties than the pore region. This boundary region has higher material density and no pores, providing localized strength and tear resistance at the edges of the membrane where stress concentrates, while the central pore region maintains thinness for high filtration efficiency.
Solution Approach 2:
The patent creates a composite structure with two distinct regions: a pore region with high porosity for filtration and a boundary region with solid polymeric material for strength. This composite approach combines the advantages of both porous and solid structures in a single membrane component.
3Manufacturing precision
If photolithography is used to define precise pore patterns, then pore uniformity improves, but the process complexity increases
Solution Approach 1:
The patent simplifies the photolithography process by removing the hard mask layer step entirely. Only a single photoresist layer is applied, patterned, and used for etching, eliminating the need for multiple layer deposition and removal steps while maintaining precise pore definition through the photoresist pattern.
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 solution produces membranes that are resistant to tearing, maintain flatness, and minimize metallic contamination, enabling denser pore distribution and thinner materials, while ensuring biocompatibility and effective filtration without curling, even at large surface areas.
Implementation Method 1
depositing a photoresist layer on the top surface of a substrate, the substrate comprising a support layer, a polymer layer, and a hard mask layer; exposing the photoresist to a pattern of light
Data Source
AI summary
Porous liquid-filtering membranes are provided having a boundary region substantially surrounding the pore region and having greater tear resistance than the pore region.