On-Die Capacitor Structure Distributing Voltage Across Power Rails
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Solution Overview
Problem
On-die capacitors (ODCs) face reliability concerns due to high voltage differences between power rails, and existing solutions to the floating metal plate issue, such as coupling with an antenna diode or complex interconnections, increase space consumption and complexity.
Innovation Solution
The proposed solution involves forming an on-die capacitor structure using two capacitors connected in series between different power supply rails, where each capacitor's terminals are directly connected to distinct power rails, distributing the voltage and minimizing the need for additional connections or complex interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two or more capacitors are connected in series to reduce voltage across each capacitor, then reliability is improved, but the floating metal plate issue arises causing non-ideal behavior
Solution Approach 1:
A dummy capacitor is introduced as an intermediary element connected in parallel with one of the series capacitors. This dummy capacitor provides a defined voltage reference that eliminates the floating metal plate issue while maintaining the voltage distribution benefits of the series connection. The dummy capacitor acts as a mediator that resolves the electrical potential ambiguity without requiring additional complex interconnections.
2Ease of operation
If the floating metal plate is coupled to an antenna diode to resolve the floating issue, then the floating metal plate issue is overcome, but the number of connections increases and space is consumed
Solution Approach 1:
The dummy capacitor is merged with the existing capacitor structure, sharing common electrodes and interconnections. Specifically, the dummy capacitor shares electrodes with the first capacitor in the series connection, allowing both capacitors to be implemented within the same physical footprint without requiring additional separate connections or components. This merging approach eliminates the need for separate antenna diode connections.
3Ease of operation
If complex interconnections are used to weakly couple the floating metal plate to a power rail, then the floating metal plate issue is resolved, but device complexity and area increase
Solution Approach 1:
The dummy capacitor serves as a simple intermediary that provides a direct electrical reference to the power rail through its parallel connection, eliminating the need for complex weak coupling interconnections. This approach reduces device complexity by replacing multi-step coupling schemes with a single straightforward parallel connection that achieves the same goal of eliminating floating potentials.
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 effectively addresses the floating metal plate issue while maintaining reliability and reducing space consumption by directly connecting capacitor terminals to power rails, enhancing the capacitance and minimizing noise in integrated circuits.
Implementation Method 1
The first capacitor has a first capacitance and the second capacitor structure has a second capacitance that is greater than the first capacitance
Data Source
AI summary
An on-die-capacitor structure includes a first capacitor and a second capacitor. The first capacitor may have first and second terminals. The first and second terminals are directly connected to first and second power supply rail structures, respectively. The first power supply rail structure is different from the second power supply rail structure. The second capacitor may have third and fourth terminals. The second capacitor is connected in series between the second power supply rail structure and a third power supply rail structure. The third power supply rail structure is different from the first and second power supply rail structures. The third and fourth terminals are directly connected to the second and third power supply rail structures, respectively. The first capacitor may have a first capacitance and the second capacitor structure may have a second capacitance that is greater than the first capacitance.