High Voltage Diode Reflecting Hole Current via N-Type Ring
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Solution Overview
Problem
High voltage diodes in integrated circuits inject significant current density into substrates, interfering with adjacent components due to undesired hole current diffusion.
Innovation Solution
A high voltage diode is formed with a p-type anode inside an n-type cathode and an uncontacted n-type diffused ring region with a higher dopant density, which reflects injected hole current back to the cathode, reducing diffusion to adjacent components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high voltage diode is used in an integrated circuit, then high voltage operation capability is achieved, but significant hole current is injected into the substrate interfering with adjacent components
Solution Approach 1:
An uncontacted n-type diffused ring region is introduced as an intermediary structure between the p-type anode and the substrate. This ring region with higher dopant density acts as a mediator that reflects hole current back toward the cathode, preventing direct injection into the substrate and protecting adjacent components while maintaining high voltage operation capability
Solution Approach 2:
The dopant density in the uncontacted n-type diffused ring region is increased to be 100 to 10,000 times higher than in the n-type cathode. This parameter change creates a potential barrier that reflects hole current back to the cathode, reducing substrate injection while preserving the diode's high voltage blocking capability
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 configuration effectively minimizes the injection of hole current into adjacent components, enhancing the operational stability of integrated circuits without increasing process complexity or cost.
Implementation Method 1
the uncontacted n-type diffused ring region reflects a portion of injected hole current from the anode back to the deep n-well cathode
Implementation Method 2
reducing the amount of injected hole current that diffuses to adjacent components in the IC
Data Source
AI summary
A high voltage diode in which the n-type cathode is surrounded by an uncontacted heavily doped n-type ring to reflect injected holes back into the cathode region for recombination or collection is disclosed. The dopant density in the heavily doped n-type ring is preferably 100 to 10,000 times the dopant density in the cathode. The heavily doped n-type region will typically connect to an n-type buried layer under the cathode. The heavily doped n-type ring is optimally positioned at least one hole diffusion length from cathode contacts. The disclosed high voltage diode may be integrated into an integrated circuit without adding process steps.