Imprint Mold Wiring Structure for Clean Via and Pad Formation
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Solution Overview
Problem
Existing methods for manufacturing multilayer wiring structures using the imprint method face challenges such as residual films obstructing interlayer connection vias, air bubbles in recesses due to uneven resin flow, and mold damage from chemical treatments used to remove adherent materials.
Innovation Solution
A method involving a mold with a rugged structure and a light-shielding layer at the top portions of the projected portions, which prevents exposure of the photo-curing insulating resist to light, allowing for easy removal of uncured resist and reducing defects. Additionally, a protective film with oxidation-resisting properties is applied to the mold to prevent damage from chemical treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photo-curing insulating resist is used to form deeper recesses for interlayer connection vias, then the rugged structure can be transferred accurately, but residual films remain between the recesses and pad portions, obstructing electrical connection
Solution Approach 1:
The mold's rugged structure is segmented into different height levels: higher projected portions for forming deeper recesses (via holes) and lower projected portions for forming shallower recesses (wiring grooves). This segmentation allows selective light exposure and curing, enabling removal of uncured resist from deeper recesses while maintaining cured resist in shallower areas, thus resolving the contradiction between pattern accuracy and connection reliability
Solution Approach 2:
The light-shielding layer is applied in advance to specific regions of the mold before the imprint process. This preliminary action ensures that light cannot reach certain areas through the mold, preventing curing of resist in deeper recesses during the initial curing step, thereby enabling subsequent easy removal of uncured resist without affecting the overall pattern structure
2Manufacturing precision
If chemical treatments are used to remove residual films from deeper recesses, then interlayer connection vias can be formed, but the mold suffers damage and its lifespan is reduced
Solution Approach 1:
The light-shielding layer is applied in advance to protect specific regions of the mold. This preliminary protective measure prevents light from curing resist in deeper recesses, allowing uncured resist to be easily removed by simple washing without requiring aggressive chemical treatments, thereby preserving the mold's integrity and extending its lifespan
Solution Approach 2:
The invention converts the potential harm of residual film obstruction into a benefit by using the light-shielding layer to create controlled uncured regions. The uncured resist, which would normally be a problem, becomes a useful feature that can be easily removed to form clean via holes, eliminating the need for damaging chemical etching processes
3Manufacturing precision
If a mold with higher projected portions is used to form deeper recesses, then interlayer connection vias can be created, but air bubbles are trapped in recesses due to uneven resin flow
Solution Approach 1:
The mold surface is given different local qualities through the light-shielding layer application. Areas with light-shielding layers have different light transmission properties compared to areas without, allowing controlled differential curing. This local quality variation enables resin to flow uniformly without trapping air bubbles, while still achieving the required recess depth variation for different structural features
4Productivity
If the entire mold surface is exposed to light for curing, then the insulating material layer can be formed, but residual films remain and obstruct electrical connections
Solution Approach 1:
The mold is given non-uniform local quality through selective application of the light-shielding layer. This creates regions with different light transmission characteristics: regions without the shielded layer allow light through for curing, while regions with the shielded layer block light to prevent curing. This local quality differentiation enables simultaneous formation of cured insulating material in some areas and uncured removable resist in others, resolving the contradiction between curing efficiency and connection reliability
Solution Approach 2:
The light-shielding layer acts as an intermediary element between the light source and the photo-curing insulating resist. It selectively controls light transmission to different regions of the mold, mediating the curing process to achieve the desired pattern of cured and uncured areas without requiring separate processing steps
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 method enables the formation of pattern structures with high accuracy, reducing warping and defects in multilayer wiring structures, while also extending the lifespan of the imprint mold by preventing damage from chemical treatments.
Implementation Method 1
a light-shielding layer provided at a desired part of top portion flat surfaces of the projected portions
Implementation Method 2
irradiation with light from the mold side is conducted to cure the photo-curing resin composition
Data Source
AI summary
A mold includes a mold base material and a rugged structure located at a main surface of the mold base material. The rugged structure includes a plurality of linearly shaped projected portions for forming wiring, and a circularly shaped projected portion for forming a pad portion, in which a light-shielding layer is provided at a top portion flat surface of the circularly shaped projected portion for forming the pad portion.