High Voltage Diode N-Type Ring Structure Leakage Path
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Solution Overview
Problem
Current high voltage diodes in CMOS technology exhibit significant leakage paths under shallow trench isolation regions, limiting their breakdown voltage to around 8 V due to parasitic diode leakage, which restricts their operation beyond 5 V.
Innovation Solution
Incorporating an N-type ring structure in the substrate that completely surrounds the diode well, spaced at a specific distance to cut off leakage paths, effectively increasing the breakdown voltage by acting as a barrier to current flow and minority carrier sinker, thereby enhancing noise suppression and supporting higher voltage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional diode structures are used in CMOS technology, then the device can be manufactured with standard processes, but the breakdown voltage is limited to around 8 V due to parasitic diode leakage under the gate STI region
Solution Approach 1:
An N-type ring structure is introduced as an intermediary element between the P-type well and the shallow N-type well under the gate. This ring structure acts as a mediator that blocks the parasitic leakage path while allowing the diode to function. The ring is spaced at a specific distance 'x' from the well to effectively cut off the leakage path without interfering with normal diode operation.
Solution Approach 2:
The well structure is segmented into multiple parts: a deep P-type well, a shallow N-type well, and an intermediate N-type ring structure. This segmentation allows the leakage path to be interrupted at the ring location while maintaining the functional p-n junction between the P-type and N-type wells. The segmentation effectively divides the continuous leakage path into disconnected segments.
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 implementation of the N-type ring structure increases the breakdown voltage of high voltage diodes, allowing for higher operating voltages and improved noise suppression, with simulated breakdown voltages reaching up to 15.5 V, compared to the conventional 8 V, while maintaining low off-state leakage current.
Implementation Method 1
an N-type ring structure in the substrate which completely surrounds the first N-well and the N+ contact, the N-type ring structure being spaced a distance 'x' from the first N-well
Implementation Method 2
a diode structure composed of first well of a first dopant type in a substrate; and a well ring structure of the first dopant type in the substrate
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to high voltage diode structures and methods of manufacture. The structure includes: a diode structure composed of first well of a first dopant type in a substrate; and a well ring structure of the first dopant type in the substrate which completely surrounds the first well of the first dopant type, and spaced a distance “x” from the first well to cut a leakage path to a shallower second well of a second dopant type.