TSV-Based Cross-Connected Diodes for Bidirectional ESD Protection
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Solution Overview
Problem
Semiconductor devices like photodiodes are vulnerable to catastrophic failure due to reverse voltage stress during electrostatic discharge (ESD) events, as current ESD protection techniques are not effective in redirecting ESD currents bidirectionally, leading to potential breakdown and damage.
Innovation Solution
The integration of through-silicon-via (TSV) technology to form protective diodes on the same semiconductor substrate as photodiodes, allowing for cross-connected anode-cathode connections and electrical isolation, enabling bi-directional ESD protection without increasing the device's size or affecting normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current ESD protection techniques are used to protect photodiodes, then forward direction ESD protection is provided, but reverse direction ESD protection is not achieved
Solution Approach 1:
The patent merges the photodiode and protective diode onto the same semiconductor substrate, sharing common TSV structures and interconnects. This integration allows the device to provide both forward and reverse direction ESD protection while maintaining compact form factor. The protective diode is formed using the same fabrication process steps as the photodiode, including shared TSV formation, enabling bi-directional protection capability.
2Reliability
If protective diodes are added to provide ESD protection, then device reliability improves, but device complexity increases
Solution Approach 1:
The protective diode and photodiode share common TSV structures, interconnect layers, and fabrication process steps. The protective diode utilizes the same substrate and interconnect infrastructure, reducing the overall device complexity compared to separate protection circuits. This merging approach provides comprehensive ESD protection while maintaining a compact and relatively simple device structure.
Solution Approach 2:
The semiconductor substrate serves multiple functions: it hosts both the photodiode and protective diode, provides mechanical support, and contains the TSV interconnect structures. The TSVs serve dual purposes as both photodiode interconnects and protective diode interconnects. This multi-functionality reduces device complexity by eliminating redundant structures.
3Reliability
If separate protection circuits are used, then ESD protection is provided, but device size increases
Solution Approach 1:
The protective diode is integrated onto the same semiconductor substrate as the photodiode, sharing common TSV structures and interconnect layers. This integration eliminates the need for separate protection circuits and reduces the overall device area. The protective diode utilizes the same fabrication process steps and substrate infrastructure, providing ESD protection in a compact footprint without increasing device size significantly.
4Reliability
If additional protection structures are added, then ESD protection capability improves, but manufacturing complexity increases
Solution Approach 1:
The protective diode and photodiode are fabricated using the same process steps on the same substrate, including shared TSV formation, doping, and interconnect deposition. This unified fabrication approach reduces manufacturing complexity compared to adding separate protection structures that would require additional process steps. The protective diode leverages the existing process infrastructure, making the manufacturing relatively straightforward.
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 solution provides effective bi-directional ESD protection for photodiodes, preventing catastrophic damage from reverse voltage stress while maintaining the device's functionality and compactness, and can be fabricated using the same process steps as the photodiodes, reducing costs and complexity.
Implementation Method 1
a cathode and an anode of the first diode are cross-connected to an anode and cathode of the second diode through the at least one TSV
Implementation Method 2
Semiconductor devices, including PN junctions, typically conduct current in the forward direction and block current in the reverse direction
Implementation Method 3
When operating in the forward direction, the PN junction is capable of conducting high current density
Data Source
AI summary
A semiconductor device formed on a substrate includes a first diode junction formation, a second diode junction formation, and at least one through-silicon-via (TSV), in which a cathode and an anode of the first diode are cross-connected to an anode and cathode of the second diode through the at least one TSV for achieving electrical robustness in through-silicon-via based integrated circuits, including photosensitive devices and circuits for signal processing applications.