Die Stacks with Bond Via Arrays and Bump Interconnects
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Solution Overview
Problem
Conventional interconnection methods for integrated circuits (ICs) face issues with solder bridging, which can lead to signal loss, attenuation, and circuit failure, particularly in three-dimensional (3D) IC packaging and die stacking configurations.
Innovation Solution
The use of bond via arrays with wires of different heights on a substrate surface, where a first bond via array with shorter wires is used for initial die interconnection, and a second bond via array with taller wires is employed for subsequent die stacking, allowing for precise positioning and reduced risk of solder bridging through the use of bump interconnects and redistribution layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interconnection methods with solder are used for die stacking, then electrical connections between dies can be established, but solder bridging occurs leading to signal loss and circuit failure
Solution Approach 1:
The patent removes solder entirely from the interconnection process by using wire bonds and bump interconnects that do not require soldering. The wire bonds are formed through fusion bonding or eutectic bonding, and the bump interconnects are made of solder-free materials, thereby extracting the harmful solder element from the system while maintaining electrical connectivity.
Solution Approach 2:
The patent introduces wire bonds as an intermediary element between the substrate and dies, and bump interconnects as intermediaries between stacked dies. These intermediaries provide electrical connection without using solder, thereby mediating the connection while avoiding the solder bridging problem.
2Manufacturing precision
If bond via arrays with wires of different heights are used for die stacking, then precise positioning and reduced solder bridging risk are achieved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating bond via arrays with wires of different heights tailored to specific locations. Shorter wires are used in regions where dies are positioned closer to the substrate, while taller wires are used in regions where dies are positioned higher in the stack. This localized differentiation enables precise positioning without requiring a uniformly complex structure throughout the entire device.
Solution Approach 2:
The patent segments the bond via array into multiple groups with different wire heights, where each segment serves a specific positioning function for different die layers. This segmentation allows the complex positioning requirements to be broken down into manageable discrete wire height categories, making the overall system more controllable despite the increased precision requirements.
Data Source
AI summary
An apparatus relating generally to a die stack is disclosed. In such an apparatus, a substrate is included. A first bond via array includes first wires each of a first length extending from a first surface of the substrate. An array of bump interconnects is disposed on the first surface. A die is interconnected to the substrate via the array of bump interconnects. A second bond via array includes second wires each of a second length different than the first length extending from a second surface of the die.