Semiconductor Super-Junction Electric Field Relaxing Electrodes
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Solution Overview
Problem
In semiconductor devices with a super-junction structure, the electric field concentrates in pn junctions other than the interfaces, leading to reduced breakdown voltage due to uneven depletion layer spread, which affects the device's performance.
Innovation Solution
The introduction of electric field relaxing electrodes above residual pn junctions with an insulating film interposed, specifically targeting the peripheral pn junctions other than the voltage holding junctions, helps to distribute the electric field uniformly and prevent concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric field relaxing electrodes are provided above residual pn junctions with an insulating film interposed, then breakdown voltage is increased, but device complexity increases
Solution Approach 1:
Electric field relaxing electrodes are selectively provided above specific residual pn junctions (peripheral junctions) rather than uniformly across all junctions. The insulating film is interposed only where needed to prevent direct contact between the electrode and semiconductor material. This localized application addresses electric field concentration problems at critical locations while avoiding unnecessary complexity in regions where the issue does not exist.
Solution Approach 2:
An insulating film is introduced as an intermediary layer between the electric field relaxing electrode and the semiconductor substrate. This insulating film enables the electrode to function in relaxing the electric field at peripheral pn junctions while preventing direct electrical contact that would create short circuits or unwanted conduction paths, thus resolving the contradiction between achieving electric field relaxation and maintaining device simplicity.
2Reliability
If electric field relaxing electrodes are added to relax electric field concentration, then manufacturing precision requirements increase
Solution Approach 1:
The electric field relaxing electrodes are positioned only above peripheral pn junctions where electric field concentration occurs, not above all pn junctions uniformly. The insulating film is applied selectively in these same regions. This localized approach concentrates manufacturing precision requirements only where they are critically needed, rather than imposing uniform high precision requirements across the entire device structure.
Solution Approach 2:
The insulating film serves as a buffer that tolerates certain variations in electrode positioning and thickness. Since the insulating film is designed with sufficient thickness to prevent direct contact even with positioning variations, it provides a margin of error that reduces the stringency of manufacturing precision requirements while still achieving the desired electric field relaxation effect.
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 solution effectively increases the breakdown voltage of the semiconductor device by relaxing electric field concentration in peripheral pn junctions, thereby enhancing the device's performance and reliability.
Implementation Method 1
electric field relaxing electrodes provided above at least some of residual pn junctions with an insulating film interposed therebetween
Data Source
AI summary
A semiconductor device includes: a drift region of a first conductive type including a contact section and extension sections extending along the main surface of a substrate; column regions of a second conductive type which alternate with the extension sections in a perpendicular direction to the extension direction of the extension sections and each includes an end connecting to the contact section; a well region of a second conductive type which connects to the other end of each column region and tips of the extension sections; and electric field relaxing electrodes which are provided above at least some of residual pn junctions with an insulating film interposed therebetween. Herein, the residual pn junctions are pn junctions other than voltage holding pn junctions formed in interfaces between the extension sections and the column regions.