Trench Semiconductor Rectifier with Guard Ring for Low Voltage Drop
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Solution Overview
Problem
Semiconductor diodes face challenges in achieving low forward voltage drop, low reverse leakage, high reverse breakdown voltage, and high avalanche ruggedness, which are essential for improving rectification efficiency and reliability, especially in high-temperature applications.
Innovation Solution
A semiconductor rectifying device is designed with a substrate of a first conductivity type, an epitaxial layer, trenches filled with insulating and conductive materials, a doped region of a second conductivity type, a guard ring, and an annular guard layer, allowing for low forward voltage drop and high reverse breakdown voltage through optimized carrier depletion and energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional silicon p-n junction diode is used, then the manufacturing process is mature and reliable, but the forward voltage drop is high (at least around 0.7 V)
Solution Approach 1:
The diode structure is segmented into multiple regions including a first conductivity type substrate, an epitaxial layer with trenches, filling structures with conductive materials, and doped regions of second conductivity type. This segmentation creates multiple conductive channels that reduce the overall forward voltage drop while maintaining compatibility with conventional silicon manufacturing processes.
Solution Approach 2:
Different regions of the diode are doped with different conductivity types and concentrations to create optimal local properties. The filling structures contain conductive materials with specific properties, while doped regions provide localized carrier injection. This local quality optimization enables low forward voltage drop in specific areas while maintaining overall device reliability.
2Loss of energy
If the forward voltage drop is reduced to improve rectification efficiency, then the rectification efficiency improves, but the reverse leakage increases
Solution Approach 1:
Guard rings of second conductivity type are introduced as intermediary structures between the active diode regions and the substrate. These guard rings act as mediators that control the electric field distribution and prevent direct breakdown paths, thereby reducing reverse leakage while allowing the main junction to operate at low forward voltage.
Solution Approach 2:
The invention employs precise control of doping concentrations, trench dimensions, and filling structure properties to optimize the balance between forward voltage drop and reverse leakage. By adjusting these parameters, the device achieves low forward voltage for high rectification efficiency while maintaining low reverse leakage through proper field control.
3Reliability
If the junction area is increased to improve avalanche ruggedness, then the energy dissipation capability improves, but the device size increases
Solution Approach 1:
The invention transitions from a planar junction structure to a three-dimensional structure with trenches and filling structures extending vertically. This dimensional change increases the effective junction area for energy dissipation without proportionally increasing the device footprint, thereby improving avalanche ruggedness while maintaining compact device size.
Solution Approach 2:
The diode incorporates composite structures combining silicon substrate, epitaxial layers, conductive filling materials, and doped regions. This composite architecture optimizes the junction area for energy dissipation in the vertical dimension while maintaining a compact lateral footprint, achieving high avalanche ruggedness without excessive device size.
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 device achieves a significant reduction in forward voltage drop, low reverse leakage, and high avalanche ruggedness, enhancing rectification efficiency and reliability while being compatible with a trench MOS process for simplified manufacturing.
Implementation Method 1
optimized carrier depletion and energy dissipation
Implementation Method 2
form a conductive channel therebetween
Implementation Method 3
high reverse breakdown voltage, and high avalanche ruggedness
Data Source
AI summary
A semiconductor rectifying device includes a substrate of a first conductivity type, an epitaxial layer of the first conductivity type, a filling structure, an upper electrode, a guard ring, and a guard layer. The epitaxial layer defines a plurality of trenches thereon. The filling structure includes an insulating material formed on the inner surface of the trench and a conductive material filled in the trench. A doped region of a second conductivity type is formed in the surface of the epitaxial layer between the filling structures. A method of manufacturing a semiconductor rectifying device includes forming an epitaxial layer of a first conductivity type on a substrate of the first conductivity type, defining a plurality of trenches on the epitaxial layer, forming a plurality of filling structures in the plurality of trenches, and forming a doped region in the epitaxial layer between the filling structures.