Bidirectional Clamp Anti-Inversion Ring Leakage Control
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Solution Overview
Problem
Integrated circuits (ICs) are vulnerable to transient electrical events such as electrostatic discharge (ESD) and electromagnetic interference (EMI), which can cause overvoltage conditions and high power dissipation, leading to damage like gate oxide punch-through, junction damage, and latch-up, necessitating effective protection mechanisms.
Innovation Solution
A bidirectional clamp is designed with a semiconductor substrate, well regions of specific conductivity types, and anti-inversion ring structures to inhibit charge trapping-induced leakage current by interrupting electrical paths at oxide-semiconductor interfaces, providing protection against ESD and EMI events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional clamp is designed to protect ICs from transient electrical events, then reliability is improved, but device complexity increases due to multiple well regions and anti-inversion ring structures
Solution Approach 1:
The bidirectional clamp is segmented into multiple functional well regions (first well region, second well region, third well region) with different conductivity types, where each region performs a specific function in protecting against transient electrical events. This segmentation allows the device to handle both positive and negative voltage transients through distributed protection mechanisms.
Solution Approach 2:
The anti-inversion ring structure acts as an intermediary element between the well regions, preventing charge trapping at oxide-semiconductor interfaces. This intermediary structure blocks the formation of inversion layers that would otherwise create leakage paths, thereby enhancing the overall protection capability without requiring complete redesign of the well structure.
2Reliability
If oxide regions are added over the third well region to prevent charge trapping, then reliability is improved, but manufacturing precision requirements increase due to oxide-semiconductor interface control
Solution Approach 1:
Oxide regions are formed over the third well region before final device assembly to preemptively prevent charge trapping at the oxide-semiconductor interfaces. This preliminary protective action ensures that even if charge trapping occurs during operation, the inverted polarity is immediately blocked, preventing leakage current without requiring post-manufacturing adjustments.
3Object-generated harmful factors
If anti-inversion ring structure is implemented to interrupt electrical paths, then leakage current is reduced, but device complexity increases
Solution Approach 1:
The anti-inversion ring structure extracts and removes the harmful inversion layer formation at the oxide-semiconductor interfaces by providing an alternative electrical path that does not involve charge trapping. This extracted protective mechanism is integrated into the existing well structure, blocking leakage current without requiring complete structural overhaul.
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
The bidirectional clamp effectively limits voltage and current, preventing damage to ICs during ESD and EMI events, ensuring reliable operation under harsh conditions with low static power dissipation and robust off-state performance.
Implementation Method 1
The anti-inversion ring structure is configured to inhibit charge trapping-induced leakage current by interrupting an electrical path from the first well region to the second well region along the plurality of oxide-semiconductor interfaces
Data Source
AI summary
Low leakage bidirectional clamps and methods of forming the same are provided. In certain configurations, a bidirectional clamp includes a first p-well region, a second p-well region, and an n-well region positioned between the first and second p-wells regions. The bidirectional clamp further includes two or more oxide regions over the n-well region, and one or more n-type active (N+) dummy blocking current regions are positioned between the oxide regions. The one or more N+ dummy leakage current blocking regions interrupt an electrical path from the first p-type well region to the second p-type well region along interfaces between the n-well region and the oxide regions. Thus, even when charge accumulates at the interfaces due to extended high voltage, e.g., >60V, and/or high temperature operation (e.g., >125° C.), the N+ dummy leakage current blocking regions inhibit charge trapping-induced leakage current.