Diode Guard Ring Leakage Current Suppression
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Solution Overview
Problem
Conventional diodes in vehicle-mounted networks experience significant leakage current due to parasitic transistors, which affects signal output accuracy and reliability.
Innovation Solution
A diode structure is designed with a p-type semiconductor substrate, an n-type semiconductor layer, a p-type isolation region, an n-type buried layer, an n-type collector wall, and a p-type guard ring to form a PNP transistor that collects leakage currents, reducing overall leakage by directing them to the cathode electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional diode structure is used, then the device complexity is low, but the leakage current increases due to parasitic transistors
Solution Approach 1:
The diode structure is segmented into multiple functional regions including a drift region, a first doped region, a second doped region, and a guard ring region. This segmentation allows each region to perform its specific function in suppressing leakage current while maintaining overall device reliability.
Solution Approach 2:
Different regions of the diode are doped with different impurity concentrations and types. The drift region has a first impurity concentration, the first doped region has a second impurity concentration, and the guard ring has a third impurity concentration. This local quality variation optimizes leakage suppression in each specific area.
2Measurement precision
If parasitic transistors are present in the diode, then the manufacturing process is simpler, but the signal output accuracy deteriorates due to leakage current
Solution Approach 1:
The parasitic transistors that cause leakage current are converted into useful components. The first parasitic transistor's leakage current is collected by the guard ring, and the second parasitic transistor's leakage current is collected by the second doped region. This converts harmful leakage into a controllable current path that improves signal output accuracy.
Solution Approach 2:
The guard ring acts as an intermediary element between the drift region and the isolation region. It intercepts leakage current from the first parasitic transistor and redirects it to the cathode, preventing the leakage from affecting the signal output accuracy.
3Reliability
If the impurity concentration in the drift region is increased, then the leakage current suppression improves, but the breakdown voltage decreases
Solution Approach 1:
The drift region is divided into zones with different impurity concentrations. The region near the anode has a higher impurity concentration to suppress leakage, while the region near the cathode maintains a lower impurity concentration to preserve breakdown voltage. This local quality variation resolves the contradiction between leakage suppression and breakdown voltage maintenance.
Solution Approach 2:
Instead of uniformly increasing impurity concentration throughout the drift region, the patent introduces a vertical dimension to impurity concentration distribution. The impurity concentration varies along the depth of the drift region, allowing optimized leakage suppression at the anode interface while maintaining low concentration at the cathode interface for high breakdown voltage.
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 diode structure effectively minimizes leakage current, ensuring accurate and reliable signal output even when the switching element is turned off, maintaining standard output signal values.
Implementation Method 1
a transistor for reducing a leakage current is formed by the p-type anode region, the p-type guard ring, and an n-type semiconductor between the p-type anode region and the p-type guard ring
Data Source
AI summary
A diode includes: a p-type semiconductor substrate; an n-type semiconductor layer; a p-type isolation region formed to surround a predetermined region of the n-type semiconductor layer on the p-type semiconductor substrate; an n-type buried layer formed across the p-type semiconductor layer and the n-type semiconductor layer within the predetermined region; an n-type collector wall formed in the n-type semiconductor layer; a p-type anode region and a plurality of n-type cathode regions formed in a diode formation region; and a p-type guard ring formed to surround the diode formation region in a region between the diode formation region of the surface layer of the n-type semiconductor layer and the p-type isolation region. A transistor for reducing a leakage current is formed by the p-type anode region, the p-type guard ring, and an n-type semiconductor between the p-type anode region and the p-type guard ring.