T-Shaped ETS Interconnects for Dense IC Package Routing
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Solution Overview
Problem
Integrated circuit (IC) packages face challenges in increasing signal routing density due to limitations in the pitch of embedded metal traces and vertical interconnects, leading to vertical connection gaps and reduced signal routing capacity.
Innovation Solution
The use of T-shaped interconnects with reduced-width embedded metal traces and additional metal contact pads in the embedded trace substrates (ETS) allows for smaller vertical interconnects while maintaining sufficient landing areas, enabling increased signal routing capacity by reducing the pitch of embedded metal traces and eliminating vertical connection gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch of embedded metal traces is reduced to increase I/O connection density, then the number of I/O connections increases, but vertical interconnects become too small causing connection gaps
Solution Approach 1:
The interconnect structure is segmented into two functional parts: a reduced-width embedded metal trace for horizontal signal routing and a wider metal contact pad for vertical interconnection. This segmentation allows each part to be optimized independently - the trace pitch can be reduced for higher density while the contact pad maintains sufficient width for reliable vertical connections.
Solution Approach 2:
Different regions of the interconnect have different width characteristics. The embedded metal trace has reduced width to enable smaller pitch, while the metal contact pad has increased width to ensure reliable vertical interconnection. This local differentiation of geometric properties resolves the contradiction between density and connection reliability.
2Area of stationary object
If the width of embedded metal traces is reduced to increase space between traces, then signal routing capacity increases, but the landing area for vertical interconnects becomes insufficient
Solution Approach 1:
The interconnect is divided into two segments with different width requirements: the embedded metal trace segment has reduced width to maximize spacing between adjacent traces, while the metal contact pad segment has increased width to provide adequate landing area for vertical interconnects.
Solution Approach 2:
The solution extends the interconnect structure in the vertical dimension by adding a metal contact pad layer above the embedded metal trace. This dimensional extension provides additional landing area without increasing the horizontal footprint, thereby preserving space between adjacent traces while ensuring sufficient connection area.
3Adaptability or versatility
If additional metal traces are added to increase signal routing capacity, then routing flexibility improves, but the pitch between existing traces must be reduced further
Solution Approach 1:
By segmenting the interconnect into reduced-width traces and wider contact pads, the effective pitch available for routing is increased compared to a uniform trace design. This allows more traces to be packed into the same horizontal space while maintaining manufacturable dimensions.
Solution Approach 2:
The geometric parameters of the interconnect are changed - specifically, the trace width is reduced and the pitch between traces is optimized. This parameter optimization enables increased signal routing capacity while maintaining reliable connections.
Data Source
AI summary
Embedded trace substrates (ETS) having an ETS metallization layer with T-shaped interconnects with reduced-width embedded metal traces, and related integrated circuit (IC) packages and fabrication methods. The ETS includes an outer ETS metallization layer that includes T-shaped interconnects for supporting input/output (I/O) connections between the ETS and another opposing package substrate. To increase density of I/O interconnections, the pitch of the embedded metal traces in the ETS metallization layer is reduced. The T-shaped interconnects also each include an additional metal contact pad that is coupled to a respective embedded metal trace to increase the height of the embedded metal trace to eliminate a vertical connection gap between the ETS and an opposing package substrate. In the T-shape interconnects, their embedded metal traces are reduced in width in a horizontal direction(s) as compared to their respective metal contact pads to provide room for additional metal traces for additional signal routing capacity.