Capacitive Coupling in Stacked Semiconductor Dies
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Solution Overview
Problem
Existing stacked semiconductor structures rely on direct electrical connections, which are complex and challenging to implement, especially for fine pitch pads, and often require large contact pads for alignment, limiting the efficiency and bandwidth of signal transfer between dies.
Innovation Solution
The use of capacitive coupling connections between stacked semiconductor dies, where communication pads communicate through bulk semiconductor material and insulating bonding layers, eliminating the need for complex metal routing and allowing for smaller, more precise pad sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct electrical connections are used between stacked dies, then electrical communication is established, but the contact pads become large and complex, limiting signal bandwidth and increasing device complexity
Solution Approach 1:
The patent replaces direct mechanical/electrical contact connections with capacitive coupling connections. Instead of using through-substrate vias and direct bonds between contact pads, the invention uses capacitive coupling through the bulk semiconductor material to transfer signals between stacked dies. This substitution eliminates the need for complex metal routing and large contact pads while maintaining reliable electrical communication.
2Manufacturing precision
If large contact pads are used for direct bonds, then alignment is improved, but chip size increases and signal bandwidth is limited
Solution Approach 1:
The capacitive coupling mechanism eliminates the need for large contact pads required for mechanical alignment in direct bonding. The capacitive connection can be established through smaller pad structures since it does not rely on direct physical contact and alignment tolerance in the same way. This reduces the area occupied by communication pads on each die while maintaining reliable signal transfer.
3Reliability
If direct bonds are used between stacked dies, then electrical connection is achieved, but signal bandwidth and transfer efficiency are limited
Solution Approach 1:
The patent changes the fundamental parameter of signal transfer from direct conductive bonding to capacitive coupling. This parameter change enables higher signal bandwidth and faster data transfer rates because capacitive coupling can operate at higher frequencies without the parasitic inductance and resistance limitations of direct metal bonds. The bulk semiconductor material acts as the dielectric medium, enabling efficient high-speed signal transfer between stacked dies.
4Reliability
If complex metal routing is used for through-substrate vias, then electrical communication is established, but manufacturing complexity increases
Solution Approach 1:
The invention replaces complex metal routing through substrate vias with a simpler capacitive coupling structure. Instead of forming through-substrate vias and depositing multiple metal layers for routing, the patent uses the bulk semiconductor material itself as the coupling medium. This eliminates numerous manufacturing steps including via drilling, plating, and metal deposition, significantly simplifying the manufacturing process while maintaining reliable electrical communication.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances signal bandwidth, reduces chip size, improves testing efficiency, and minimizes crosstalk among high-frequency channels, while providing a robust and scalable electrical connection method.
Implementation Method 1
at least one of the first communication pads communicates a non-noise signal capacitively with at least one of the second communication pads
Implementation Method 2
the first die includes an insulating first bonding layer over the first device surface, the first bonding layer defining a first front surface of the first die, and the second die includes an insulating second bonding layer over the second back surface
Data Source
AI summary
A multi-die electronic apparatus is disclosed. The multi-die electronic apparatus can comprise a first die comprising first communication pads, the first die having a first device surface including first devices, and a first back surface opposite the first device surface. A second die can include second communication pads, the second die having a second device surface including second devices, and a second back surface opposite the first device surface. The first and second dies can be vertically stacked with the second back surface facing the first device surface. At least one of the first communication pads can communicate a non-noise signal capacitively with at least one of the second communication pads.