Offset 3D Die Stack Layout for Interposer-Free Bandwidth
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Solution Overview
Problem
Conventional 2.5D IC packaging techniques face limitations due to microbumps with 50-150 micron pitches and interposers with only three metal layers, resulting in reduced communication bandwidth between dice and data routing bottlenecks.
Innovation Solution
The implementation of a high-bandwidth 3D die stack where dice are connected in an offset manner, allowing for communication via dice in a layer above or below, with each die having 15+ metal layers and a finer pitch (less than 10 microns), eliminating the need for an interposer and enabling direct coupling to a PCB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 2.5D IC packaging with interposer is used, then multiple dice can communicate within a single package, but the microbump pitch (50-150 microns) and limited metal layers (three) reduce communication bandwidth
Solution Approach 1:
The patent removes the interposer from the packaging structure, eliminating the bottleneck component that limited bandwidth. By directly coupling dice to the PCB substrate, the design extracts the problematic intermediate layer that constrained microbump pitch and metal layer count, enabling higher bandwidth communication without the interposer's limitations
Solution Approach 2:
The patent transitions from a 2.5D planar arrangement with interposer to a 3D stacked configuration where dice are vertically positioned above PCB pads. This dimensional change enables finer pitch (less than 10 microns) and allows 15+ metal layers per die to be utilized, dramatically increasing communication bandwidth by exploiting the vertical dimension
2Productivity
If interposer with three metal layers is used, then routing is simplified, but data routing bottlenecks occur due to limited routing capacity
Solution Approach 1:
The patent changes the parameter of metal layer count from three (in interposer) to 15+ (in each die), fundamentally increasing routing capacity. This parameter change eliminates data routing bottlenecks by providing sufficient routing resources within each die to handle high-bandwidth communication without relying on the limited interposer metal layers
3Reliability
If conventional 2.5D packaging is used, then dice can be connected, but packaging size, cost, and complexity increase due to interposer requirement
Solution Approach 1:
The patent extracts and removes the interposer component entirely from the packaging structure, reducing packaging complexity, size, and cost. By establishing direct coupling between dice and PCB substrate, the design eliminates the unnecessary intermediate component while maintaining full connectivity functionality
Solution Approach 2:
The patent merges the functions of the interposer and PCB substrate by having dice couple directly to PCB pads. This consolidation eliminates the separate interposer layer, reducing packaging complexity and enabling direct integration of dice into the PCB structure, thereby simplifying the overall packaging architecture
Data Source
AI summary
Examples herein describe techniques for producing a three-dimensional (3D) die stack. The techniques include stacking a first die on top of a second die. The first die is offset from the second die in at least one of an x-direction and a y-direction, and a first routing sub-region of the first die aligns with a second routing sub-region of the second die. The techniques further include stacking a third die on top of the second die. The third die is offset from the second die in at least one of the x-direction and the y-direction, and a third routing sub-region of the third die aligns with a fourth routing sub-region of the second die.