Double-Sided Inter-Die Bonding for Noise Reduction
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Solution Overview
Problem
The challenge in stacked die assemblies is to minimize noise and signal interference while accommodating increasing inter-die electrical connections without occupying additional wafer space, particularly when routing power signals near noise-sensitive logic circuits in semiconductor devices.
Innovation Solution
A stacked die assembly with double-sided inter-die bonding connections is implemented, featuring a vertical stack of bonded units with memory and logic dies, where upward-facing and downward-facing external bonding pads are connected by separate sets of bonding wires, optimizing wire routing to reduce noise interference and utilize space efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If power signals are routed near logic circuits in stacked die assemblies, then electrical connections are established, but noise level in the logic circuit increases
Solution Approach 1:
The patent utilizes double-sided bonding to exploit the vertical dimension by forming bonding pads on both the front and back surfaces of semiconductor dies. This allows electrical connections to be established in three-dimensional space, separating power signal routing from noise-sensitive logic circuits vertically rather than only horizontally, thereby reducing noise interference while maintaining connection density
Solution Approach 2:
The bonding pads are segmented into front-side pads and back-side pads, allowing separate routing paths for different signal types. Power signals can be routed through back-side pads away from front-side logic circuits, while logic signals use front-side pads, thus segmenting the electrical connection paths to minimize noise coupling
2Adaptability or versatility
If the number of semiconductor dies in a stacked die assembly increases, then functionality is enhanced, but the number of inter-die electrical connections increases
Solution Approach 1:
By utilizing both front and back surfaces of each die for bonding pad formation, the patent effectively doubles the available connection interface area. This vertical expansion of the bonding interface allows multiple dies to be stacked with reduced connection complexity, as connections can be established at multiple vertical levels rather than requiring all connections at a single interface
Solution Approach 2:
The double-sided bonding structure creates a nested configuration where intermediate dies in the stack can have connections established on both their front and back surfaces, allowing signal routing to penetrate through the stack depth. This nesting of connection paths through multiple vertical levels reduces the overall complexity by distributing connections throughout the stack rather than concentrating them at interfaces
3Quantity of substance
If external bonding pads are increased for wire bonding, then connectivity is improved, but wafer space is occupied
Solution Approach 1:
The patent forms external bonding pads on both the front surface and back surface of the semiconductor die, utilizing the vertical dimension to double the available pad area without increasing the die's planar footprint. This allows more wire bonding connections to be established while maintaining the same wafer space utilization
Solution Approach 2:
External bonding pads are segmented into front-side pads and back-side pads, which can be independently optimized for different wire bonding requirements. This segmentation allows the total pad count to increase while distributing them across two surfaces, thereby reducing the space requirement on each individual surface
Data Source
AI summary
Multiple bonded units are provided, each of which includes a respective front-side die and a backside die. The two dies in each bonded unit may be a memory die and a logic die configured to control operation of memory elements in the memory die. Alternatively, the two dies may be memory dies. The multiple bonded units can be attached such that front-side external bonding pads have physically exposed surfaces that face upward and backside external bonding pads of each bonded unit have physically exposed surfaces that face downward. A first set of bonding wires can connect a respective pair of front-side external bonding pads, and a second set of bonding wires can connect a respective pair of backside external bonding pads.