Core Metallization Routing in Package Substrates for Higher Density
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Solution Overview
Problem
Existing package substrates face limitations in signal routing flexibility and density due to the use of vertical interconnects that extend through the entire core height, leading to increased package size and resistance, while thicker cores for support result in height increases and process limitations on metal fill, causing dimples and connectivity issues.
Innovation Solution
Incorporating multiple core metallization layers within the package substrate, made from hardened dielectric material, allows for lateral signal routing and reduced aspect ratios, enhancing routing density and flexibility without increasing package height, using semi-additive process (SAP) or embedded trace substrate (ETS) metallization layers for finer pitch interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vertical interconnects extend through the entire core height to provide signal routing, then connectivity between metallization layers is achieved, but package height increases and resistance increases
Solution Approach 1:
The patent divides the single vertical interconnect path into multiple segments by introducing intermediate horizontal routing layers. Signals are routed vertically only partially through the core, then switch to horizontal routing on intermediate layers, and continue vertically if needed. This segmentation reduces the length of any single vertical interconnect while maintaining end-to-end connectivity.
Solution Approach 2:
The patent transitions from purely vertical signal routing to a three-dimensional routing architecture that utilizes horizontal dimensions through intermediate metallization layers. By allowing signals to route horizontally on intermediate layers before continuing vertically, the design reduces vertical interconnect length while providing alternative signal paths.
2Strength
If core thickness is increased to provide support for larger die packages, then warpage is reduced, but metal fill process becomes limited causing dimples and connectivity issues
Solution Approach 1:
The patent segments the metal fill process into multiple steps corresponding to different routing layers. Instead of filling one tall vertical interconnect through the entire core thickness, the process fills metal in stages on intermediate layers, then creates via connections between these shorter segments. This reduces the height of individual metal fill operations while achieving the same overall vertical connectivity.
Solution Approach 2:
The patent performs preliminary routing on intermediate metallization layers before completing the final vertical connections. By establishing horizontal routing paths and via locations in advance, the design allows subsequent metal fill operations to be performed on shorter, more manageable segments rather than attempting to fill one continuous tall interconnect.
3Reliability
If traditional vertical interconnect routing is used, then signal routing is achieved, but routing flexibility and density are limited
Solution Approach 1:
The patent adds horizontal routing dimensions by introducing intermediate metallization layers between the top and bottom metallization layers. This transforms the routing architecture from a single vertical dimension to a three-dimensional space, allowing signals to switch between vertical and horizontal paths and significantly increasing routing flexibility and density.
Data Source
AI summary
Package substrate with a core having metallization layers to facilitate signal routing within the core, and related fabrication methods and integrated circuit (IC) packages. The core includes multiple core metallization layers that can be formed separately and coupled to each other to provide signal routing within the core. Metal interconnects in the multiple core metallization layers are coupled to each other through coupling of the core metallization layers to each other in the core to provide signal routing paths through the core. Including separate core metallization layers in the core provides flexibility in patterning location of the metal interconnects therein for routing flexibility within the core. This is opposed to only including singular body, vertical interconnects extending through the entire height of the core. Metal interconnects can also be patterned to extend laterally within a respective core metallization layer to provide lateral signal routing paths within a core metallization layer.