Guard Ring Wiring Board Suppressing Leakage Current
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Solution Overview
Problem
The existing wiring boards with through electrodes in semiconductor substrates suffer from increased leakage current due to inversion layers formed around through holes, which deteriorate the insulation characteristics and lead to characteristic degradation of semiconductor elements.
Innovation Solution
The implementation of guard rings with specific conductivity types surrounding the through electrodes to prevent inversion layer formation and the use of a second guard ring to getter contaminants, thereby reducing leakage current and maintaining semiconductor element characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If through holes and through electrodes are formed in the semiconductor substrate to enable electrical connection between wirings, then electrical connectivity is improved, but leakage current increases due to inversion layer formation around the through holes
Solution Approach 1:
A guard ring structure is introduced as an intermediary element between the through electrode and the semiconductor substrate elements. The guard ring, formed with a specific conductivity type (opposite to the substrate), acts as a mediator that prevents direct electrical interaction between the through electrode and the substrate, thereby blocking the inversion layer formation and eliminating the leakage current path while maintaining the through electrode's electrical connectivity function
Solution Approach 2:
The patent applies local quality by creating a region with different conductivity characteristics (the guard ring) in a specific location surrounding the through electrode. This localized modification of electrical properties allows the through electrode to maintain its connectivity function while the guard ring locally suppresses the harmful inversion layer effect, thus resolving the contradiction between connectivity and leakage current
2Reliability
If impurity concentration of the semiconductor substrate is reduced to form semiconductor elements, then element characteristics are improved, but inversion layer formation becomes more prone to occur around through electrodes
Solution Approach 1:
The guard ring serves as a protective intermediary that shields the low-impurity semiconductor substrate from the electric field effects of the through electrode. By placing the guard ring between the through electrode and the substrate elements, it prevents the electric field from inducing inversion layers in the low-impurity substrate, thus allowing the substrate to maintain its low impurity concentration for better element characteristics without suffering from inversion layer formation
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 guard rings effectively suppress the formation of inversion layers and prevent leakage current increases, ensuring the integrity of semiconductor element characteristics by managing impurity concentrations and contaminant intrusion.
Implementation Method 1
when the impurity concentration of a semiconductor substrate is low, an inversion layer is formed within the semiconductor substrate by a potential difference between through electrodes and the semiconductor substrate upon applying power
Implementation Method 2
diffusion and intrusion of Cu from the through electrodes or intrusion of contaminants (e.g., Fe, Na, K and the like) from the outside
Data Source
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AI summary
There is provided a wiring board 10. The wiring board 10 includes: a semiconductor substrate 17 having a through hole 32 and covered with an insulating film 18; a through electrode 21 formed in the through hole 32; a first wiring 26 connected to one end of the through electrode 21; and a second wiring 28 connected to the other end of the through electrode 21. The semiconductor substrate 17 includes: a semiconductor element and a first guard ring 24 formed to surround the through hole 32. The semiconductor clement includes a first conductivity-type impurity diffusion layer 35 having a different conductivity-type from that of the semiconductor substrate and is electrically connected to the first wiring 26 and the second wiring 28.