Wiring Substrate Trench Structure to Prevent Via-Related Shorts
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Solution Overview
Problem
Existing wiring substrates face issues with short circuiting between adjacent wiring layers due to the formation of cavities during the manufacturing process, particularly when forming via holes and trenches in insulating layers.
Innovation Solution
The design incorporates a trench that is recessed from the surface of the insulating layer and does not extend through it, separated from the via hole, with a conductive layer filling the trench to prevent short circuits by containing any voids or gaps that could form during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via holes and trenches are formed in insulating layers to connect wiring layers, then electrical connectivity between wiring layers is achieved, but cavities and voids may form causing short circuits between adjacent wiring layers
Solution Approach 1:
The patent converts the harmful effect of voids and cavities into a beneficial structure by filling trenches with conductive layers. The trenches, which would normally create harmful voids, are instead filled with conductive material that prevents short circuits while maintaining electrical connectivity. This transforms the potential harm into a protective feature.
Solution Approach 2:
The conductive layer acts as an intermediary substance filling the trenches between wiring layers. This intermediary material prevents direct contact between adjacent wiring layers through the voids, thereby preventing short circuits while still allowing electrical connectivity through the via holes. The conductive layer mediates between the wiring layers to eliminate the harmful effect.
2Reliability
If trenches are formed to prevent short circuits, then electrical insulation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the trench formation process with the via hole formation process. Both trenches and via holes are created in the same insulating layer using similar manufacturing steps, and both are filled with conductive material in the same process sequence. This consolidation reduces manufacturing complexity compared to treating trench and via hole formation as separate processes.
Solution Approach 2:
The conductive layer serves multiple functions: it fills trenches to prevent short circuits, provides electrical connectivity where needed, and acts as part of the wiring structure. This multi-functionality reduces the need for additional separate components or processes, thereby reducing overall manufacturing complexity.
Data Source
AI summary
A wiring substrate includes a first wiring layer located on an upper surface of a first insulating layer, a second insulating layer located on the first insulating layer and covering the first wiring layer, a via hole extending through the second insulating layer in a thickness-wise direction and exposing the first wiring layer, and a trench recessed from an upper surface of the second insulating layer. The wiring substrate further includes a via wiring filling the via hole, a conductive layer filling the trench, and a second wiring layer electrically connected to the first wiring layer by the via wiring and located on the upper surface of the second insulating layer. The trench does not extend through the second insulating layer in the thickness-wise direction. The trench is arranged peripheral to the via hole and separated from the via hole. The trench overlaps the second wiring layer in plan view.